Journal: Heart Rhythm

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Abstract

Clinical Significance of Myocardial Scar in Patients With Frequent Premature Ventricular Complexes Undergoing Catheter Ablation.

Ghannam M, Yokokawa M, Liang J, Cochet H, ... Morady F, Bogun F
Background
Frequent ventricular complexes (PVC) can result in PVC-induced cardiomyopathy (PICM). Scarring has been described in patients with frequent PVCs in the absence of apparent heart disease and in patients with known cardiomyopathy.
Objective
The purpose of this study was to determine the impact of focal myocardial scarring as detected by cardiac magnetic imaging on PICM, procedural outcomes, and recovery of left ventricular function in patients with frequent PVCs.
Methods
A total of 351 consecutive patients (181 males, age 53+15 years, EF 51±12%) with frequent PVCs referred for ablation were included. A CMR was performed in all patients prior to the ablation procedure. A ≥10% increase in EF or normalization of a previously abnormal EF was defined as evidence of PICM.
Results
Myocardial scarring was present in 134/351(38%) patients and 66/134(49%) patients with scarring and 54/217(25%) patients without scarring had improvement or normalization of the EF after ablation. The presence of myocardial scarring, a PVC burden > 22%, male gender, asymptomatic status, and a PVC-QRS width of >150 ms were associated with PICM by univariate analysis (P<0.01 for all). The presence of scar was independently associated with PICM (OR 2.2[1.3 - 3.7], P<0.005. In patients with scarring, the success rate of PVC ablation was lower than in patients without focal scarring (mean of 70% vs 82%, P<0.01).
Conclusions
Focal scar defined by CMR is independently associated with PICM. While ablation outcomes are worse in the presence of scarring, EF recovery can occur in most of these patients after ablation.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 24 Jul 2020; epub ahead of print
Ghannam M, Yokokawa M, Liang J, Cochet H, ... Morady F, Bogun F
Heart Rhythm: 24 Jul 2020; epub ahead of print | PMID: 32721479
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Abstract

The rationale for repurposing funny current inhibition for management of ventricular arrhythmia.

Chakraborty P, Rose RA, Nair K, Downar E, Nanthakumar K

Management of ventricular arrhythmia in structural heart disease is complicated by the toxicity of the limited antiarrhythmic options available. In others, pro-arrhythmia, deleterious hemodynamic, and noncardiac effects prevent practical use. This necessitates new thinking in therapeutic agents for ventricular arrhythmia in structural heart disease. Ivabradine, a funny current (I) inhibitor, has proven safety in heart failure, angina, and inappropriate sinus tachycardia. Though it is commonly known that funny channels are primarily expressed in the sinoatrial node, atrioventricular node, and conducting system of the ventricle, ivabradine is known to exert effects on metabolism, ion homeostasis and membrane electrophysiology of remodeled ventricular myocardium. This review considers novel concepts and evidence from clinical and experimental studies regarding this paradigm with a potential role of ivabradine in ventricular arrhythmia.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 28 Jul 2020; epub ahead of print
Chakraborty P, Rose RA, Nair K, Downar E, Nanthakumar K
Heart Rhythm: 28 Jul 2020; epub ahead of print | PMID: 32738405
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Abstract

Global Electrical Heterogeneity Associated with Drug-Induced Torsades de Pointes.

Stabenau HF, Shen C, Zimetbaum P, Buxton AE, Tereshchenko LG, Waks JW
Background
Drugs belonging to diverse therapeutic classes can prolong myocardial refractoriness or slow conduction. These drugs may be effective and well-tolerated, but the risk of sudden cardiac death from torsades de pointes (TdP) remains a major concern. The corrected QT interval has significant limitations when used for risk stratification. Measurement of GEH could help identify the substrate vulnerable to drug-induced ventricular arrhythmias.
Objectives
To improve risk stratification for drug-induced TdP by measuring global electrical heterogeneity (GEH) on the ECG.
Methods
We analyzed electrocardiographic data from a case-control study of patients with a history of drug-induced TdP, as well as age- and sex-matched controls. Vectorcardiograms were constructed from ECGs. GEH was measured via the spatial ventricular gradient (SVG) vector (magnitude, azimuth, and elevation). Log odds coefficients for TdP were estimated using multivariable logistic regression.
Results
Among 17 cases and 17 controls (47% and 29% male, age 58.9 ± 12.5 and 61.0 ± 12.2 years), 34 ECGs were analyzed. SVG azimuth was significantly different between cases and controls (3.4 vs 22.0 deg, p = 0.02). After adjusting for gender and QTc interval, odds of TdP increased by a factor of 3.2 for each 1 standard deviation change in SVG azimuth from the control group mean (p = 0.04, 95% CI 1.07-9.14). QTc was not significant in the multivariable analysis (p = 0.20).
Conclusions
SVG azimuth is correlated with a history of drug-induced TdP independent of the QTc. GEH measurement may help identify patients at high risk for drug induced arrhythmias.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 07 Aug 2020; epub ahead of print
Stabenau HF, Shen C, Zimetbaum P, Buxton AE, Tereshchenko LG, Waks JW
Heart Rhythm: 07 Aug 2020; epub ahead of print | PMID: 32781158
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Abstract

Predictors of Atrial Mechanical Sensing and Atrioventricular Synchrony with a Leadless Ventricular Pacemaker: Results from the MARVEL 2 Study.

Garweg C, Khelae SK, Steinwender C, Sun Chan JY, ... Wood N, Chinitz L
Background
The MARVEL 2 study assessed the efficacy of atrio-ventricular synchronous pacing with a Micra leadless pacemaker. Average AV synchrony (AVS) was 89.2%. Previously, low amplitude of the Micra-sensed atrial signal (A4) was observed to be a factor of low AVS.
Objective
To identify predictors of A4 amplitude and high AVS.
Methods
We analyzed 64 patients enrolled in MARVEL 2 with visible P-waves on ECG for assessing A4 amplitude and 40 patients with 3 degree AV block for assessing AVS at rest. High AVS was defined as >90% correct atrial-triggered ventricular pacing. The association between clinical factors and echocardiographic parameters with A4 amplitude was investigated using a multivariable model with lasso variable selection. Variables associated with A4 amplitude together with premature ventricular contraction burden, sinus rate, and sinus rate variability (standard deviation of successive P-P intervals [SDSD]) were assessed for association with AVS.
Results
In univariate analysis, low A4 amplitude was inversely related to atrial function assessed by E/A ratio and e\'/a\' ratio and directly related to atrial contraction excursion (ACE), and atrial strain (Ɛa) on echocardiography (all P≤0.05). The multivariable lasso regression model found CABG history, E/A ratio, ACE, and Ɛa associated with low A4 amplitude. E/A ratio and SDSD were multivariable predictors of high AVS, with >90% probability if E/A<0.94 and SDSD<5bpm.
Conclusion
Clinical parameters and echocardiographic markers of atrial function are associated with A4 signal amplitude. High AV synchrony can be predicted by E/A ratio<0.94 and low sinus rate variability at rest.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 23 Jul 2020; epub ahead of print
Garweg C, Khelae SK, Steinwender C, Sun Chan JY, ... Wood N, Chinitz L
Heart Rhythm: 23 Jul 2020; epub ahead of print | PMID: 32717315
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Abstract

Is Competitive Atrial Pacing a Possible Trigger for Atrial Fibrillation? Observations from the RATE Registry.

Orlov MV, Olshansky B, Benditt DG, Kotler G, ... Poghosyan H, Waldo AL
Background
A high incidence of asymptomatic atrial tachycardia and atrial fibrillation (AT/AF) has been recognized in patients with cardiac implantable devices (CIED). The clinical significance of these AT/AF episodes remains unclear. Some \"device detected AT/AF\" was previously shown to be triggered by competitive atrial pacing (CAP).
Objective
To investigate and characterize a potential association between CAP and AT/AF in the largest series of observations to date.
Methods
RATE, multicenter registry, included 5,379 patients with CIEDs followed for approximately two years. Electrograms (EGMs) from 1,352 patients with AT/AF, CAP, or both were analyzed by experienced adjudicators to assess a causal relationship between AT/AF and CAP onset, duration, and morphology.
Results
In 225 patients, 1,394 episodes of both AT/AF and CAP were present in the same tracing. CAP and AT/AF were strongly associated (p<0.02). AT/AF occurred during the course of the study in 71% of patients with CAP. In 62% of the episodes, expert adjudication concluded that CAP triggered AT/AF. The duration and morphology of triggered and spontaneous AT/AF episodes differed. Spontaneous AT/AF episodes were associated with constant EGM morphology, and were either long or extremely short. CAP-triggered AT/AF more often had variable and shorter cycle length EGMs. The incidence of short AT/AF events was higher among triggered episodes (25% versus 12.8%, p <0.002).
Conclusion
Device triggered AT/AF due to CAP is likely more common than previously recognized. This AT/AF entity differs from spontaneous AT/AF in duration and morphology. Clinical implications of spontaneous and device triggered AT/AF may be different.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 28 Jul 2020; epub ahead of print
Orlov MV, Olshansky B, Benditt DG, Kotler G, ... Poghosyan H, Waldo AL
Heart Rhythm: 28 Jul 2020; epub ahead of print | PMID: 32738404
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Abstract

Simultaneous activation of the small conductance calcium activated potassium current by acetylcholine and inhibition of sodium current by ajmaline cause J-wave syndrome in Langendorff-perfused rabbit ventricles.

Fei YD, Chen M, Guo S, Ueoka A, ... Weiss JN, Chen PS
Background
Concomitant apamin-sensitive small conductance, calcium activated potassium current (I) activation and I inhibition induce J-wave syndrome (JWS) in rabbit hearts. Sudden death in JWS occurs predominantly in men at night, when parasympathetic tone is strong.
Objective
To test the hypotheses that acetylcholine (ACh), the parasympathetic transmitter, activates I and causes JWS in the presence of ajmaline.
Methods
We performed optical mapping in Langendorff-perfused rabbit hearts and whole-cell voltage clamp to determine I in isolated ventricular cardiomyocytes.
Results
ACh (1 μM) + ajmaline (2 μM) induced J-point elevations in all (6 male and 6 female) hearts from 0.01± 0.01 to 0.31 ± 0.05 mV (p<0.001), which were reduced by apamin (specific I inhibitor, 100 nM) to 0.14 ± 0.02 mV (p<0.001). More J-point elevation was noted in males than females (p=0.037). Patch clamp studies showed that ACh significantly (p<0.001) activated I in isolated male but not female ventricular myocytes (n=8). Optical mapping studies showed that ACh induced action potential duration (APD) heterogeneity, which was more significant in right than left ventricles. Apamin in the presence of ACh prolonged both APD (p<0.001) and APD (p<0.001), and attenuated APD heterogeneity. Ajmaline further increased APD heterogeneity induced by ACh. Ventricular arrhythmias were induced in 6/6 male and 1/6 female hearts (p= 0.015) in the presence of ACh and ajmaline, which was significantly suppressed by apamin in the former.
Conclusion
ACh activates ventricular I. ACh and ajmaline induce J-wave syndrome and facilitate the induction of ventricular arrhythmias more in male than female ventricles.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 03 Aug 2020; epub ahead of print
Fei YD, Chen M, Guo S, Ueoka A, ... Weiss JN, Chen PS
Heart Rhythm: 03 Aug 2020; epub ahead of print | PMID: 32763429
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Abstract

Progressive Implantable Cardioverter-Defibrillator Therapies for Ventricular Tachycardia: The Efficacy and Safety of Multiple Bursts, Ramps, and Low-Energy Shocks.

Strik M, Ramirez FD, Welte N, Bonnin T, ... Ploux S, Bordachar P
Background
The HRS/EHRA/APHRS/LAHRS expert consensus statement on optimal implantable cardioverter-defibrillator (ICD) programming recommends burst antitachycardia pacing (ATP) for treatment of ventricular tachycardia (VT) up to very high rates. The number of bursts is not specified and treatment by ramps or low-energy shocks are not recommended.
Objective
We investigated the efficacy and safety of progressive therapies for treatment of VTs between 150 to 200 bpm. After three failed bursts, we compared three ramps versus three bursts followed by low-energy shock versus high-energy shock.
Methods
Using remote monitoring, we included monomorphic VT episodes treated with ≥1 burst.
Results
1126 VT episodes were included. A single burst was as likely to terminate VT between 150-200 bpm as VT between 200-230 bpm (63% versus 64%, P=0.41), but was more likely to accelerate the latter (3.2% versus 0.25%, P<0.01). For VT <200 bpm, the likelihood of ATP success increased progressively (73% with 2 bursts, 78% with 3 bursts). Three additional bursts further increased VT termination to 89%, similar to the success rate with 3 additional ramps (88%, P=0.17). Programming 6 bursts is associated with probability of acceleration requiring shock of 6.6%. Low-energy first shock was less successful than high-energy (66% versus 86%, p<0.01) and more likely to accelerate VT (17% versus 0%, p<0.01).
Conclusion
Programming up to six burst ATP therapies for VTs 150-200 bpm can avoid ICD shocks in most patients. Ramp ATP after failed bursts were similarly effective. Low-energy shocks are less effective and more arrhythmogenic than high-energy shocks.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 29 Jul 2020; epub ahead of print
Strik M, Ramirez FD, Welte N, Bonnin T, ... Ploux S, Bordachar P
Heart Rhythm: 29 Jul 2020; epub ahead of print | PMID: 32739474
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Abstract

Impact of preoperative electrophysiological intervention on occurrence of peri/postoperative supraventricular tachycardia following Fontan surgery.

Takeuchi D, Toyohara K, Kudo Y, Nishimura T, Shoda M
Background
Little is known about the effects of preoperative electrophysiological study (EPS) and catheter ablation (CA) in Fontan surgery candidates with supraventricular tachycardia (SVT).
Objective
This study aimed to investigate the clinical impact of EPS-guided intervention in Fontan surgery candidates with preceding SVT events.
Methods
A total of 109 consecutive patients with a history of SVT before Fontan surgery were divided into three groups: 44, in whom EPS with CA was attempted (CA group);21,in whom EPS without CA was attempted (EPS group); and 44,in whom EPS was not performed (N group). The incidence and diagnosis of SVT, acute success rate of CA, and risk factors of peri/postoperative SVT were retrospectively investigated.
Results
The total incidence of SVT within one year after Fontan surgery was 34% (n= 37), with 91% of cases occurring within one month. Among the 71 SVT incidences diagnosed with EPS, 31 were atrioventricular reentrant tachycardias (AVRTs) involving twin atrioventricular nodes, 12 were atrioventricular nodal reentrant tachycardias, 12 were atrial tachycardias, seven were orthodromic AVRTs via the accessory pathway, seven were atrial flutters, and two were junctional tachycardias. The acute success rate of CA was 91% (48/53). The rate of peri/postoperative atrioventricular-reciprocating SVT was significantly lower in the CA group than the N or EPS group (11% vs. 43% or 43%, p< 0.05). No/unsuccessful CA significantly increased the risk of peri/postoperative SVT in multivariate analysis (odds ratio, 4.43;95% confidence interval, 1.69-11.59).
Conclusion
Preoperative CA reduces peri/postoperative SVT occurrence in Fontan surgery candidates at high risk of SVT.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 07 Aug 2020; epub ahead of print
Takeuchi D, Toyohara K, Kudo Y, Nishimura T, Shoda M
Heart Rhythm: 07 Aug 2020; epub ahead of print | PMID: 32781159
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Abstract

Morbidity and mortality in patients precluded for transvenous pacemaker implantation: Experience with a leadless pacemaker.

Garg A, Koneru JN, Fagan DH, Stromberg K, ... Cheng A, Ellenbogen KA
Background
The Micra transcatheter pacemaker is a safe and effective alternative to transvenous permanent pacemakers (TV-PPMs). However, the safety profile and mortality outcomes of Micra implantation in patients deemed poor candidates for TV-PPM is incompletely understood.
Objective
To evaluate the safety and all-cause mortality in patients undergoing Micra implantation stratified by if they were precluded for therapy with a TV-PPM.
Methods
Patients from the Micra clinical trials were divided into groups based upon whether the implanter considered the patient to be precluded from receiving a TV-PPM. Micra groups were compared to one another as well as a historical cohort of patients who received a single-chamber TV-PPM.
Results
2,817 patients underwent a Micra implantation attempt, of which 546 patients deemed ineligible for TV-PPM implantation for reasons such as venous access issues or prior device infections. Both acute mortality (2.75% vs 1.32%, p= 0.022) and total mortality at 36 months (38.1% vs 20.6%, p<0.001) were significantly higher in the precluded group compared to the non-precluded group. Mortality was similar among non-precluded patients and patients implanted with a TV-PPM. The major complication rate through 36-months was similar between the two Micra groups (3.81% vs 4.30%, p=0.40).
Conclusion
All-cause mortality is higher in Micra patients deemed ineligible for a TV-PPM as compared to non-precluded Micra patients and those who received TV-PPM, in part related to higher incidence of chronic comorbidities in these patients. The overall major complication rate was low and did not differ by preclusion status.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 03 Aug 2020; epub ahead of print
Garg A, Koneru JN, Fagan DH, Stromberg K, ... Cheng A, Ellenbogen KA
Heart Rhythm: 03 Aug 2020; epub ahead of print | PMID: 32763431
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Abstract

Premature Ventricular Complex Site of Origin and Ablation Outcomes in Patients with Prior Myocardial Infarction.

Penela D, Teres C, Fernández-Armenta J, Aguinaga L, ... Mont L, Berruezo A
Background
Frequent premature ventricular complexes (PVCs) are common after a myocardial infarction (MI), but data on PVC ablation in this population is limited.
Objective
To analyze data on PVC ablation in post-MI patients.
Methods
332 patients with frequent PVC and left ventricular (LV) dysfunction were prospectively included. Data from 67 (20%) patients [63±10 years old, 65 (93%) men] with previous MI were compared with the remaining 265 patients.
Results
PVCs in post-MI patients originate predominantly from the LV [92% LV vs 6% right ventricle (RV), p<0.001], the most frequent sites of origin (SOO) being MI scar [23 (34%) patients] and the LV outflow-tract (LVOT) [22 (33%) patients]. A papillary muscle origin was more frequent in post-MI patients (16% vs 4%, p=0.001), while a RV outflow-tract (RVOT) origin was less frequent (1% vs 33%, p<0.001), as compared to patients without MI. In post-MI patients PVC burden decreased from 29±12% at baseline to 4.6±7% (p<0.001), LVEF improved from 33.6±8% to 42±10% (p<0.001), and NYHA class improved from 2.1±0.7 to 1.4±0.5 points (p<0.001) at 12 months. When compared with the remaining 265 patients, there were no differences in the acute ablation success (85% vs 85%, p=0.45), complication rate (6% vs 6%, p= 0.41) or absolute improvement in LVEF (8.8±10 vs 9.9±11 absolute points, p=0.38).
Conclusion
PVC ablation significantly improves cardiac function and functional status in post-MI patients. PVCs predominantly originate from the MI scar and LVOT. A papillary muscle SOO was found to be strongly associated to the presence of a previous MI.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 03 Aug 2020; epub ahead of print
Penela D, Teres C, Fernández-Armenta J, Aguinaga L, ... Mont L, Berruezo A
Heart Rhythm: 03 Aug 2020; epub ahead of print | PMID: 32763430
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Abstract

Mind the gap: knowledge deficits in evaluating young sudden cardiac death.

Paratz E, Semsarian C, La Gerche A

Sudden cardiac arrest affects around half a million people aged under 50 years old annually with a ninety percent mortality rate. Despite high patient numbers and clear clinical need to improve outcomes, many gaps exist in the evidence underpinning patients\' management. Domains identifying the greatest barriers to conducting trials are the pre-hospital and forensic settings, who also provide care to the majority of patients. Addressing gaps in evidence along each point of the cardiac arrest trajectory is a key clinical priority.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 24 Jul 2020; epub ahead of print
Paratz E, Semsarian C, La Gerche A
Heart Rhythm: 24 Jul 2020; epub ahead of print | PMID: 32721478
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Abstract

Effect of QRS area reduction and myocardial scar on the hemodynamic response to cardiac resynchronization therapy.

Okafor O, Umar F, Zegard A, van Dam P, ... Marshall H, Leyva F
Background
Vectorcardiographic QRS area (QRS ) predicts clinical outcomes after cardiac resynchronization therapy (CRT). Myocardial scar adversely affects clinical outcomes after CRT.
Objective
To determine whether, in patients with an ideally deployed quadripolar left ventricular (LV) lead (QUAD), reducing QRS leads to an acute hemodynamic response (AHR); and, whether scar affects this interaction.
Methods
Patients (n=26, aged 69.2 ± 9.12 years [mean ± SD]) underwent assessment of the maximum rate of change of LV pressure (ΔLV dP/dt) during CRT using various LV pacing locations (LVPLs). A cardiac magnetic resonance (CMR) scan was used to localize LV myocardial scar.
Results
Interindividually, ΔQRS (area under the receiver-operating characteristic curve AUC]: 0.81, p<0.001) and change in QRS duration (ΔQRSd) (AUC: 0.76, p<0.001) predicted ΔLV dP/dt after CRT. Scar burden correlated with ΔQRS (r=0.35, p=0.003), ΔQRS (r=0.35, p=0.003) and ΔQRSd (r=0.46, p<0.001). A reduction in QRS was observed with LVPLs remote from scar (-3.28 ± 38.1μVs) or in LVPLs in patients with no scar at all (-43.8 ± 36.8 μVs), whereas LVPLs over scar increased QRS (22.2 ± 58.4 μVs) (p<0.001 for all comparisons). LVPLs within 1 scarred LV segment were associated with a lower ΔLV dP/dt (-2.21 ± 11.5%) than LVPLs remote from scar (5.23 ± 10.3%, p<0.001) or LVPLs in patients with no scar at all (10.2 ± 7.75%) (both p<0.001).
Conclusion
Reducing QRS improves the AHR to CRT. Myocardial scar adversely affects ΔQRS and the AHR. These findings may support the use of ΔQRS and CMR in optimizing CRT using QUAD.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 23 Jul 2020; epub ahead of print
Okafor O, Umar F, Zegard A, van Dam P, ... Marshall H, Leyva F
Heart Rhythm: 23 Jul 2020; epub ahead of print | PMID: 32717314
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Abstract

Primary Prevention Implantable Cardioverter Defibrillators in Hypertrophic Cardiomyopathy - Are There Predictors of Appropriate Therapy?

Weissler-Snir A, Dorian P, Rakowski H, Care M, Spears D
Background
Identifying hypertrophic cardiomyopathy (HCM) patients who warrant a primary-prevention implantable cardioverter defibrillator(ICD) is crucial. ICDs are effective in terminating life-threatening arrhythmias; however, ICDs carry risks of complications.
Objectives
To assess the incidence and predictors of appropriate ICD therapies, inappropriate shocks and device-related complications in HCM patients with primary-prevention ICDs.
Methods
All HCM patients who underwent primary-prevention ICD implantation at Toronto General Hospital between 9/2000-12/2017 were identified. Therapies (shocks or anti-tachycardia pacing) for ventricular tachycardia>180bpm or ventricular fibrillation were considered appropriate.
Results
302 patients were followed for a mean 6.1 years(1,801 patient years follow-up). 38 patients(12.6%) received at least one appropriate ICD therapy(2.3%/year); 5-year cumulative probability of receiving appropriate ICD therapy 9.6%. None of the conventional risk factors nor the European Society of Cardiology risk-score were associated with appropriate ICD therapy. On multivariable analysis, age<40 at implant and atrial fibrillation were independent predictors of appropriate ICD therapy. In a sub-group of patients who had cardiac magnetic resonance imaging prior to ICD implantation, severe late gadolinium enhancement (LGE) was the strongest predictor of appropriate ICD therapies. ICD-related complications or inappropriate shocks occurred in 28.8% of patients, with an inappropriate shock rate of 2.1%/year; 5-year cumulative probability 10.7%.
Conclusion
The incidence of appropriate ICD therapies in HCM patients with primary-prevention ICDs is lower than previously reported; a high proportion of patients suffer an ICD-related complication. Traditional risk factors have low predictive utility. Severe LGE, atrial fibrillation and young age are important predictors of ventricular tachyarrhythmias in HCM.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 11 Aug 2020; epub ahead of print
Weissler-Snir A, Dorian P, Rakowski H, Care M, Spears D
Heart Rhythm: 11 Aug 2020; epub ahead of print | PMID: 32800967
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Abstract

Unexpected high failure rate of a specific MicroPort/LivaNova/Sorin pacing lead.

Haeberlin A, Anwander MT, Kueffer T, Tholl M, ... Roten L, Noti F
Background
Pacing leads are the Achilles heel of pacemakers. Most manufacturers report a 3-year survival rate of >99% of their leads. We observed several failures of the Beflex™/Vega™ leads (MicroPort, formerly Sorin/LivaNova).
Objective
To investigate failure rates of Beflex™/Vega™ leads.
Methods
We analyzed the performance of Beflex™/Vega™ leads implanted at our tertiary referral center. All-cause lead failures (any issues requiring re-interventions such as lead dislocations, cardiac perforations, electrical abnormalities) were identified during follow-up. The Beflex™/Vega™ lead was compared to a reference lead (Medtronic CapSureFix Novus 5076™) implanted within the same period and by the same operators.
Results
585 leads were analyzed (382 Beflex™/Vega™ and 203 CapSureFix Novus 5076™ leads). Cumulative failure rate estimates were 5.2%, 6.3%, and 12.4% after one, two, and three years for the Beflex™/Vega™ lead. This was worse compared to the reference lead (1.5%, 1.5%, 3.7% after one, two, and three years, p=0.001). Early failure manifestations up to 3 months occurred at a similar rate (1.3% vs. 0.5% for dislocations; 1.3% vs. 1.0% for perforations (Beflex™/Vega™ vs. CapSureFix Novus 5076™ lead)). During follow-up, electrical abnormalities such as noise oversensing (p=0.013) and increased pacing thresholds (p=0.003) became more frequent in the Beflex™/Vega™ group. Electrical abnormalities were the most common failure manifestation three years after implantation in this group (9.4% vs. 2.2% for the CapSureFix Novus 5076™).
Conclusion
The failure rate of the Beflex™/Vega™ lead of >10% after three years was higher compared to a competitor lead. This gives rise to concern since >135\'000 such leads are active worldwide.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 12 Aug 2020; epub ahead of print
Haeberlin A, Anwander MT, Kueffer T, Tholl M, ... Roten L, Noti F
Heart Rhythm: 12 Aug 2020; epub ahead of print | PMID: 32798776
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Abstract

Higher baseline cardiorespiratory fitness is associated with lower arrhythmia recurrence and death after atrial fibrillation ablation.

Donnellan E, Wazni OM, Harb S, Kanj M, Saliba WI, Jaber WA
Background
Cardiorespiratory fitness (CRF) has been shown to correlate with incident atrial fibrillation (AF) and AF burden. In recent years there has been increasing recognition of the pivotal role of modifying risk factors before AF ablation.
Objective
The purpose of this study was to investigate whether higher baseline CRF measured using exercise stress testing (EST) was associated with improved outcomes after AF ablation.
Methods
We studied 591 patients who underwent EST within 12 months before AF ablation. Patients were categorized into low (<85% predicted), adequate (85%-100% predicted), and high (>100% predicted) CRF groups. Outcomes of interest included arrhythmia recurrence, cessation of antiarrhythmic therapy, repeat hospitalization for arrhythmia, repeat rhythm control procedures, and all-cause mortality.
Results
During mean follow-up of 32 months after ablation, arrhythmia recurrence was observed in 79% of patients in the low CRF group compared to 54% in the adequate CRF group and 27.5% in the high CRF group (P <.0001). Similarly, rates of repeat arrhythmia-related hospitalization, repeat rhythm control procedures, and need for ongoing antiarrhythmic therapy were significantly lower in the high CRF group (P <.0001). Death occurred in 2.5% of patients in the high CRF group compared to 4% in the adequate CRF group and 11% in the low CRF group (P <.0001). In Cox proportional hazards analyses, high CRF was significantly associated with lower arrhythmia recurrence.
Conclusion
Higher CRF is associated with reduced arrhythmia recurrence rates and death among patients undergoing AF ablation. Efforts should be made to enhance CRF before AF ablation.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 23 Jul 2020; epub ahead of print
Donnellan E, Wazni OM, Harb S, Kanj M, Saliba WI, Jaber WA
Heart Rhythm: 23 Jul 2020; epub ahead of print | PMID: 32762978
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Abstract

N-terminal pro-B-type natriuretic peptide is a specific predictor of appropriate device therapies in patients with primary prevention ICDs.

Sroubek J, Matos J, Locke A, Kaplinskiy V, ... Shen C, Buxton AE
Background
Sudden death risk stratification of patients with LV systolic dysfunction remains challenging. Retrospective studies have suggested N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be a useful risk-stratification tool.
Objective
To ascertain the utility of NT-proBNP as a predictor of appropriate ICD therapies in primary prevention ICD recipients.
Methods
This is a prospective study of 342 stable patients with LVEF≤40%, receiving a primary prevention ICD. NT-proBNP assay was performed at the time of device implant and used as a dichotomized variable (1-3 NT-proBNP quartiles vs 4 NT-proBNP quartile) to predict primary (appropriate ICD therapies) and secondary (death, ICD-deactivation, chronic inotropic support, transplant) outcomes.
Results
Median follow-up was 35.0 (IQR 15.2-55.3) months. In unadjusted analyses, NT-proBNP predicted both primary (HR=1.89 (95%CI 1.00-3.56), p=0.049) and secondary outcomes (HR=2.13 (95%CI 1.18-3.85), p=0.012). Multivariable analysis reaffirmed NT-proBNP as a primary outcome predictor (HR=4.31 (95%CI 1.92-9.70), p<0.001) but not as a secondary outcome predictor (HR=1.23 (95%CI 0.61-2.50), p=0.564). Instead, secondary outcome was predicted by patients\' age and renal function. In an unadjusted sub-analysis limited to patients with BUN<30 mg/dL, NT-proBNP remained a primary endpoint predictor (HR=2.51 (95%CI 1.25-5.05), p=0.010) but not a secondary endpoint predictor (HR 1.34 (95%CI 0.52-3.44), p=0.541). Receiver operating analyses at 2-year and 3-year follow-up timepoints confirmed that NT-proBNP significantly improved the performance of multivariable models designed to predict future appropriate ICD therapies.
Conclusion
In multivariable analysis NT-proBNP is a reasonable and specific predictor of future appropriate device therapies primary prevention ICD recipients. In contrast, adjusted NT-proBNP does not predict all-cause mortality.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 27 Aug 2020; epub ahead of print
Sroubek J, Matos J, Locke A, Kaplinskiy V, ... Shen C, Buxton AE
Heart Rhythm: 27 Aug 2020; epub ahead of print | PMID: 32866691
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Impact:
Abstract

Risk of Arrhythmic Events Following Alcohol Septal Ablation for Hypertrophic Cardiomyopathy Using Continuous Implantable Cardiac Monitoring.

Bleszynski PA, Goldenberg I, Fernandez G, Howell E, ... Cove C, Aktas MK
Background
Alcohol septal ablation (ASA) in hypertrophic cardiomyopathy (HCM) patients can lead to heart rhythm disturbances including complete heart block (CHB), atrial and ventricular arrhythmias.
Objective
We aimed to evaluate the utility of long-term arrhythmia monitoring with an implantable cardiac monitor (ICM) following ASA.
Methods
Between February 2014 to March 2019, 56 HCM patients undergoing ASA were enrolled in a prospective study and underwent ICM implant. Kaplan-Meier survival analysis was used to assess the rate of ICM detected arrhythmic events.
Results
Mean age was 59±11 years and 20 (36%) were women. The median (25th, 75th percentiles) resting left ventricular (LV) outflow tract gradient by echo was 43 (22, 81) mmHg. Greater than 1 septal perforator was injected in 48 (86%) patients. The Kaplan-Meier cumulative rate of ICM detected arrhythmic events at 18 months of follow-up was 71%, with an event rate of 43% occurring within 3 months following ASA. The cumulative rate of ICM detected first atrial fibrillation (AF) event at 18 months was 37%; and the corresponding rate of CHB was 19%. All AF and CHB events were actionable, leading to initiation of anticoagulation and pacemaker implantation, respectively. No baseline demographic or procedural variables were identified as independent predictors of increased risk for the development of ICM-detected arrhythmic events.
Conclusion
Following ASA, an ICM is effective in capturing clinically actionable arrhythmic events in HCM patients regardless of patient\'s baseline risk factors.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 23 Aug 2020; epub ahead of print
Bleszynski PA, Goldenberg I, Fernandez G, Howell E, ... Cove C, Aktas MK
Heart Rhythm: 23 Aug 2020; epub ahead of print | PMID: 32853778
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Impact:
Abstract

Right Bundle Branch Block Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy More Commonly Originates from the Right Ventricle: Criteria for Identifying Chamber of Origin.

Marchlinski DF, Tschabrunn CM, Zado ES, Santangeli P, Marchlinski FE
Background
Right-bundle branch block (RBBB) ventricular tachycardia (VT) morphology is a criterion for left ventricular (LV) involvement in arrhythmogenic right ventricular cardiomyopathy (ARVC).
Objective
We sought to determine the frequency and chamber of origin of RBBB VT in patients with ARVC and VT.
Methods
We studied 110 consecutive patients with VT who met the diagnostic International Task Force Criteria for ARVC and underwent VT mapping/ablation. Patients with ≥1 RBBB VT were identified. RV origin for the RBBB VT was determined based on standard mapping criteria and elimination with ablation.
Results
Nineteen patients (17%) had 26 RBBB VTs. Eleven of these 19 patients (58%) had 16 RBBB VTs from the RV and 9 patients (47%) had 10 RBBB VTs originating from the LV with one patient demonstrating both. RBBB VT from RV, most commonly (13/16 RBBB VTs), had an early precordial QRS transition, V2 or V3, with superiorly and typically leftward directed frontal plane axis, consistent with exit from dilated RV adjacent to inferior LV septum, whereas all 10 VTs from LV had RBBB morphology had positive R waves to V5 or V6 and rightward axis in 6 VTs characteristic of basal, lateral origin.
Conclusions
In patients with ARVC and VT presenting for VT ablation, RBBB VT occurs in 17% of cases with most RBBB VTs (62%) actually originating from the RV and not indicative of LV origin. The precordial R wave transition and frontal plane axis can be used to identify the anticipated chamber of origin of RBBB VT.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 31 Aug 2020; epub ahead of print
Marchlinski DF, Tschabrunn CM, Zado ES, Santangeli P, Marchlinski FE
Heart Rhythm: 31 Aug 2020; epub ahead of print | PMID: 32889109
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Impact:
Abstract

Safety of Magnetic Resonance Imaging Scanning in Patients with Cardiac Resynchronization Therapy Defibrillators Incorporating Quadripolar Left Ventricular Leads.

Rinaldi CA, Vitoff PJ, Nair DG, Bernstein R, ... Tse HF, Green UB
Background
Magnetic resonance imaging of MR Conditional cardiac implantable cardioverter-defibrillators (ICDs) can be safely scanned following specific protocols. MRI safety with cardiac resynchronization-therapy defibrillators (CRT-Ds) incorporating quadripolar left ventricular (LV) leads is less clear.
Objective
Evaluate the safety and effectiveness of ICDs and CRT-D systems with quadripolar LV leads following an MRI scan.
Methods
The ENABLE MRI Study included 230 subjects implanted with an Image Ready ICD (n=39) or CRT-D (n=191) incorporating quadripolar LV leads undergoing non-diagnostic 1.5 Tesla (T) MRI scans (lumbar and thoracic spine imaging) a minimum of 6 weeks post-implant. Pacing capture thresholds (PCT), sensing amplitudes (SA) and impedances were measured pre- and 1-month post-MRI using the same programmed LV pacing vectors. The ability to sense/treat ventricular fibrillation (VF) was assessed in a subset of patients.
Results
159 patients completed a protocol-required MRI scan (MR protection mode turned on) with no scan-related complications. All RV and LV PCT and SA effectiveness endpoints were met: RV PCT 99% (145/146 patients), LV PCT 100% (120/120), RV SA 99% (145/146) and LV SA 98% (116/118). There were no instances where MRI resulted in a change in pacing vector or lead revision. All episodes of VF were appropriately sensed and treated.
Conclusions
This first evaluation of predominantly CRT-D systems with quadripolar LV leads undergoing 1.5T MRI confirmed scanning was safe with no significant change in RV/LV PCT, SA, programmed vectors and VF treatment suggesting MRI in patients with quadripolar leads can be performed without negatively impacting CRT delivery. (246 words).

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 06 Sep 2020; epub ahead of print
Rinaldi CA, Vitoff PJ, Nair DG, Bernstein R, ... Tse HF, Green UB
Heart Rhythm: 06 Sep 2020; epub ahead of print | PMID: 32911050
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Impact:
Abstract

Electrical and structural remodeling contribute to atrial fibrillation in type 2 diabetic db/db mice.

Bohne LJ, Jansen HJ, Daniel I, Dorey TW, ... Ezeani M, Rose RA
Background
Atrial fibrillation (AF) is highly prevalent in diabetes mellitus (DM), yet the basis for this is poorly understood. Type 2 DM may be associated with unique patterns of atrial electrical and structural remodeling; however, this has not been investigated in detail.
Objective
To investigate AF susceptibility and atrial electrical and structural remodeling in type 2 diabetic db/db mice.
Methods
AF susceptibility and atrial function were assessed in male and female db/db mice and age-matched wildtype littermates. Electrophysiology studies were conducted in vivo using intracardiac electrophysiology and programmed stimulation. Atrial electrophysiology was also investigated in isolated atrial preparations using high-resolution optical mapping and in isolated atrial myocytes using patch-clamping. Molecular biology studies were performed using qPCR and Western blotting. Atrial fibrosis was assessed using histology.
Results
db/db mice were highly susceptible to AF in association with reduced atrial conduction velocity, action potential duration prolongation and increased heterogeneity in repolarization in left and right atria. In db/db mice atrial K currents, including the transient outward current (I) and the ultra-rapid delayed rectifier current (I), were reduced. The reduction in I occurred in association with reductions in Kcnd2 mRNA expression and K4.2 protein levels. The reduction in I was not related to gene or protein expression changes. Interstitial atrial fibrosis was increased in db/db mice.
Conclusion
Our study demonstrates that increased susceptibility to AF in db/db mice occurs in association with impaired electrical conduction as well as electrical and structural remodeling of the atria.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 06 Sep 2020; epub ahead of print
Bohne LJ, Jansen HJ, Daniel I, Dorey TW, ... Ezeani M, Rose RA
Heart Rhythm: 06 Sep 2020; epub ahead of print | PMID: 32911049
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Impact:
Abstract

Computer versus Cardiologist: Is a machine learning algorithm able to outperform an expert in diagnosing phospholamban (PLN) p.Arg14del mutation on ECG?

Bleijendaal H, Ramos LA, Lopes RR, Verstraelen TE, ... Wilde AAM, Pinto Y
Background
Phospholamban (PLN) p.Arg14del mutation carriers are known to develop dilated and/or arrhythmogenic cardiomyopathy and typical electrocardiographic (ECG) features have been identified for diagnosis. Machine learning is a powerful tool used in ECG analysis and has shown to outperform cardiologists.
Objective
We aimed to develop machine learning and deep learning models to diagnose PLN p.Arg14del cardiomyopathy using ECGs and evaluate their accuracy compared to an expert cardiologist.
Methods
We included 155 adult PLN mutation carriers and 155 age- and sex matched control subjects. 21 (13.4%) PLN mutation carriers were classified as symptomatic (symptoms of heart failure or malignant ventricular arrhythmias). The dataset was split into training and testing sets using 4-fold cross-validation. Multiple models were developed to discriminate between PLN mutation carrier or control subject. For comparison, expert cardiologists classified the same dataset. The best performing models were validated using an external PLN p.Arg14del mutation carriers dataset from Murcia, Spain (n= 50). We applied occlusion maps to visualize the most contributing ECG regions.
Results
In terms of specificity, the expert cardiologists (0.99) outperformed all models (range 0.53-0.81). In terms of accuracy and sensitivity the experts (0.28 and 0.64) was outperformed by all models (sensitivity range 0.65-0.81). T-wave morphology was most important for classification of PLN p.Arg14del. External validation showed comparable results, with the best model outperforming the experts.
Conclusion
This study shows that ML can outperform experienced cardiologists in the diagnosis of PLN p.Arg14del cardiomyopathy and suggests that the shape of the T-wave is of added importance to this diagnosis.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 06 Sep 2020; epub ahead of print
Bleijendaal H, Ramos LA, Lopes RR, Verstraelen TE, ... Wilde AAM, Pinto Y
Heart Rhythm: 06 Sep 2020; epub ahead of print | PMID: 32911053
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Impact:
Abstract

Cardiac arrhythmias and sudden unexpected death in epilepsy: results of long-time monitoring.

Serdyuk S, Davtyan K, Burd S, Drapkina O, ... Gusev E, Topchyan A
Background
Cardiac rhythm and conduction disorders are common in patients with epilepsy and are presumably one of the leading causes of sudden unexpected death. There are only a few published reports on ictal cardiac arrhythmias detected by continuous monitoring, and the majority had a small sample size.
Objective
The aim of this study is the evaluation of frequency and type of cardiac arrhythmias recorded by an implantable loop recorder in patients with drug-resistant epilepsy.
Methods
We implanted a subcutaneous loop recorder to 193 patients with drug-resistant epilepsy. Automatic triggers to initiate cardiac rhythm recording were cardiac pauses >3 sec., any episodes of bradycardia (≤45beats per min) or tachycardia (≥150 beats per min). The patients/ relatives were instructed to start peri-ictal rhythm recording using an external activator device. The follow-up duration was thirty-six months, with scheduled follow-up visits every three months.
Results
6494 electrocardiogram traces were recorded during the median follow-up of 36 [3-36] months. Ictal heart rhythm and rate changes were detected in 143 patients (74%). The most common finding was ictal sinus tachycardia (66.8%). Sinus bradycardia was observed in 13 patients (6.7%). Three patients developed clinically relevant cardiac pauses >6sec, requiring permanent pacemaker implantation. Five patients (2.6%) died suddenly.
Conclusion
Ictal heart rhythm and rate changes occur in most of the patients with drug-resistant epilepsy. Clinically relevant cardiac events, related to ictal and postictal periods, are rare. No potentially malignant arrhythmias were detected in patients who died suddenly during the preceding follow-up period.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 06 Sep 2020; epub ahead of print
Serdyuk S, Davtyan K, Burd S, Drapkina O, ... Gusev E, Topchyan A
Heart Rhythm: 06 Sep 2020; epub ahead of print | PMID: 32911052
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Impact:
Abstract

Effects of 60-Hertz Notch Filtering on Local Abnormal Ventricular Activities.

Zhou X, Jiang MY, Sohinki D, Liu W, Po SS
Background
It is known that electrical signals can be affected by notch filtering.
Objectives
We sought to investigate the impact of 60-Hz notch filtering on local ventricular abnormal activities (LAVA) in patients undergoing ventricular tachycardia ablation.
Methods
To ensure catheter stability, only patients undergoing ablation using Stereotaxis mapping catheters were enrolled. Catheter stability was judged by the display on the electro-anatomical map and the morphology of the bipolar and unipolar electrograms of the ablation catheter. At sites recording stable LAVA, 60-Hz notch filtering was applied. The duration, amplitude and morphology of LAVA were compared before and after filtering. Area-under-LAVA was used to analyze the amplitude of continuous LAVA.
Results
A total of 110 LAVA potentials recorded from 13 patients were analyzed. Notch filtering significantly affected the LAVA morphology and reduced their amplitude (the sum of the absolute value of the largest positive and negative voltage before filtering: 0.267 mV [0.191, 0.395]; after filtering: 0.172 mV [0.112, 0.266]; p<0.001). At least 2 high-frequency components were introduced into the LAVA by filtering at 33 sites. Area-under-continuous-LAVA was reduced by 28% from 24.64 cm (16.20, 33.45) to 17.53 cm (10.52, 23.82) (p<0.001). The duration of continuous LAVA was reduced by 12% from 79.2 msec (55.0, 93.0) to 69.5 msec (53.0, 88.5) (p<0.001).
Conclusion
Notch filtering can distort LAVA by reducing their amplitude, changing their morphology and shortening their duration, leading to potential false positives and negatives. Mitigating the 60-Hz noise should focus on eliminating the source of noise, not applying notch filtering.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 06 Sep 2020; epub ahead of print
Zhou X, Jiang MY, Sohinki D, Liu W, Po SS
Heart Rhythm: 06 Sep 2020; epub ahead of print | PMID: 32911051
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Impact:
Abstract

Axillary vein puncture guided by ultrasound vs cephalic vein dissection in pacemaker and defibrillator implant: A multicenter randomized clinical trial.

Tagliari AP, Kochi AN, Mastella B, Saadi RP, ... Saadi EK, Polanczyk CA
Background
Axillary vein puncture guided by ultrasound (US-Ax) has emerged as a valid alternative access route to pacemaker and defibrillator lead insertion.
Objective
The purpose of this study was to evaluate whether US-Ax compared to cephalic vein dissection (CV) improves success and early complications in pacemaker or defibrillator implant.
Methods
This prospective, multicenter clinical trial included 88 adult patients randomized 1:1 to US-Ax (n = 44) or CV (n = 44). All procedures were performed by operators with no previous experience in axillary approach. Primary endpoint was defined as success rate. Secondary endpoints were venous access site change, time to obtain venous access, total procedural time, and early complication rate. Analyses were performed using the intention-to-treat principle.
Results
Median age was 70.5 years (58.2-79.7), and 60.2% were male. For the primary outcome, a higher success rate was observed in the axillary group (97.7% vs 54.5%; P <.001), as well as a lower rate of venous access site change (2.3% vs 40.9%; P <.001) and shorter time to obtain venous access (5 vs 15 minutes; P <.001) and procedural time (40 vs 51 minutes; P = .010), with no difference in complication rate (2.3% vs 11.4%; P =.20). In multivariate analysis, US-Ax (P <.001), single-chamber device (P = .015), and body mass index (P = .015) were independent predictors of overall success.
Conclusion
This is the first randomized trial comparing self-learned US-Ax to CV in cardiac lead implantation. Our results indicate that the axillary approach was superior in terms of success rate, time to obtain venous access and procedural time, with similar complication rate.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1554-1560
Tagliari AP, Kochi AN, Mastella B, Saadi RP, ... Saadi EK, Polanczyk CA
Heart Rhythm: 30 Aug 2020; 17:1554-1560 | PMID: 32360827
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Impact:
Abstract

Long QT Syndrome Type 1 and 2 Patients Respond Differently to Arrhythmic Triggers - The TriQarr In Vivo Study.

Marstrand P, Almatlouh K, Kanters JK, Graff C, ... Bundgaard H, Theilade J
Background
In patients with long QT syndrome (LQTS), swimming and loud noises have been identified as genotype-specific arrhythmic triggers in LQTS type 1 and LQTS type 2, respectively.
Objective
To compare LQTS groups\' responses to arrhythmic triggers.
Methods
LQTS1 and LQTS2 patients were included. Before and after beta blocker intake, electrocardiograms were recorded as participants: 1) were exposed to a loud noise of ∼100 dB. 2) immersed face into cold water.
Results
Twenty-three patients (9 LQTS1 and 14 LQTS2) participated. In response to noise, LQTS groups increased heart rate similarly, but LQTS2 patients prolonged their QTcF (Fridericia) significantly more than LQTS1: 37±8 vs. 15±6 ms (p=0.02). After intake of beta blocker, the QTcF prolongation in LQTS2 patients was significantly blunted and similar to LQTS1 (p=0.90). In response to simulated diving, LQTS groups experienced a heart rate drop of ∼28 bpm, which shortened QTcF similarly in both groups. After intake of beta blockers, heart rate dropped 28±2 bpm in LQTS1 patients and 20±3 bpm in LQTS2, resulting in slower heart rate in LQTS1 compared with LQTS2 (p=0.01). In response, QTcF shortened similarly in LQTS1 and LQTS2 patients: 57±9 vs. 36±7 ms (p=0.10).
Conclusion
When exposed to noise, LQTS2 patients prolonged their QTc significantly more than LQTS1 patients. Importantly, beta blockers reduced the noise-induced QTc prolongation in LQTS2 patients - demonstrating the protective effect of beta blockers. In response to simulated diving, LQTS groups responded similarly, but a slower heart rate was observed in LQTS1 patients during simulated diving after beta blockers.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 30 Aug 2020; epub ahead of print
Marstrand P, Almatlouh K, Kanters JK, Graff C, ... Bundgaard H, Theilade J
Heart Rhythm: 30 Aug 2020; epub ahead of print | PMID: 32882399
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Impact:
Abstract

Right Bundle Branch Block-type Wide QRS Complex Tachycardia with a Reversed R/S Complex in Lead V6: Development and Validation of Electrocardiographic Differentiation Criteria.

Kim M, Kwon CH, Lee JH, Hwang KW, ... Park HS, Nam GB
Background
Differentiation of supraventricular tachycardia (SVT) with right bundle branch block (RBBB)-pattern from ventricular tachycardia (VT) is difficult, particularly when the R/S ratio in lead V6 is below 1.0.
Objective
We sought to investigate the electrocardiographic (ECG) criteria for distinguishing between these arrhythmias.
Methods
We investigated ECG parameters from 111 consecutive patients who had RBBB-pattern wide QRS complex tachycardia (WCT) with a reversed R/S ratio in lead V6 (72 VTs, 39 SVTs). Diagnostic criteria from the previous algorithms were compared with our new criterion, the RS/QRS ratio, which was defined as the ratio of the interval from the onset of the QRS to the nadir of S wave, divided by the QRS width in lead V6. The RS/QRS ratio was further tested in a prospective population (31 fascicular VTs, 29 SVTs).
Results
The diagnostic accuracy of previous criteria (Brugada, Vereckei, R-wave peak time criterion) was only modest. However, the RS/QRS ratio in lead V6 was significantly lower in SVT than in VT (0.36±0.04 vs. 0.50±0.08, P <0.001). A cutoff value of the RS/QRS ratio >0.41 differentiated VT from SVT with a high diagnostic accuracy (sensitivity:97.2%, specificity:89.7%). When tested in a prospective population of fascicular VT, diagnostic accuracy of the criteria was maintained (sensitivity:90.3%, specificity:86.2%) Conclusion: The RS/QRS ratio >0.41 in lead V6 is a simple and reliable index for distinguishing VT from SVT in an RBBB-pattern WCT with a reversed R/S complex in lead V6. This criterion was particularly useful for differential diagnosis of fascicular VT from RBBB-pattern SVT.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 10 Sep 2020; epub ahead of print
Kim M, Kwon CH, Lee JH, Hwang KW, ... Park HS, Nam GB
Heart Rhythm: 10 Sep 2020; epub ahead of print | PMID: 32927100
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Impact:
Abstract

Significance of fragmented QRS complexes for predicting new-onset atrial fibrillation after cavotricuspid isthmus-dependent atrial flutter ablation.

Fujimoto Y, Yodogawa K, Oka E, Hayashi H, ... Hayashi M, Shimizu W
Background
Atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) are 2 separate entities that coexist in a significant proportion of patients. In patients with CTI ablation of AFL, the decision to hold anticoagulation often becomes an issue.
Objectives
This study aimed to describe the incidence of the development of AF after CTI ablation in patients without a history of AF and to identify the risk predictors of the occurrence of AF.
Methods
The present study included 120 consecutive patients (106 men; mean age 68 ± 12 years) who underwent radiofrequency catheter ablation (RFCA) of typical AFL since 2010. Patients with a history of AF before RFCA were excluded. The P-wave and QRS morphology, characteristics, and duration were evaluated by 12-lead electrocardiography the day after ablation.
Results
During 3.6 ± 2.6 years of follow-up after RFCA, 49 patients (41%) developed new-onset AF. A univariate analysis revealed that the presence of fragmented QRS (fQRS) complexes (hazard ratio [HR], 4.63; 95% confidence interval [CI] 2.31-9.29; P < .001) and advanced interatrial block (IAB), defined as P-wave duration > 120 ms and biphasic morphology in the inferior leads (HR 4.44; 95% CI 2.45-8.01; P < .001), were predictors of new-onset AF. A multivariate analysis revealed that fQRS complexes (HR 3.35; 95% CI 1.58-7.10; P = .002) and advanced IAB (HR 2.64; 95% CI 1.38-5.07; P < .004) were independent predictors.
Conclusion
The present study indicated that new-onset AF developed in a significant proportion of patients undergoing AFL ablation. The presence of fQRS complexes and advanced IAB were predictors of new-onset AF.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1493-1499
Fujimoto Y, Yodogawa K, Oka E, Hayashi H, ... Hayashi M, Shimizu W
Heart Rhythm: 30 Aug 2020; 17:1493-1499 | PMID: 32325199
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Impact:
Abstract

Modern mapping and ablation techniques to treat ventricular arrhythmias from the left ventricular summit and interventricular septum.

Romero J, Shivkumar K, Valderrabano M, Diaz JC, ... Natale A, Di Biase L

Managing arrhythmias from the left ventricular summit and interventricular septum is a major challenge for the clinical electrophysiologist requiring intimate knowledge of cardiac anatomy, advanced training and expertise. Novel mapping and ablation strategies are needed to treat arrhythmias originating from these regions given the current suboptimal long-term success rates with standard techniques. Herein, we describe innovative approaches to improve acute and long-term clinical outcomes such as mapping and ablation using the septal coronary venous system and the septal coronary arteries, alcohol ablation, coil embolization, and ablation of all early sites among others.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1609-1620
Romero J, Shivkumar K, Valderrabano M, Diaz JC, ... Natale A, Di Biase L
Heart Rhythm: 30 Aug 2020; 17:1609-1620 | PMID: 32333973
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Impact:
Abstract

Tachyarrhythmia discriminator for implantable cardioverter-defibrillators in bundle branch block.

Kapoor R, Tyagi S, Dohmen C, Oujiri J, ... Rubenstein JC, Berger M
Background
Inaccurate arrhythmia classification by implantable cardioverter-defibrillators (ICDs) contributes to inappropriate shocks and increased health care utilization.
Objective
The purpose of this study was to evaluate the ability of a novel discriminator using far-field (FF) and near-field (NF) right ventricular lead electrograms (EGMs) to differentiate ventricular tachycardia (VT) from supraventricular tachycardia (SVT) in patients with underlying conducted narrow QRS, right bundle branch block (RBBB), and left bundle branch block (LBBB).
Methods
ICD interrogations were reviewed, identifying subjects with tachycardia events at least 5 beats in duration with stable morphology and cycle length. FF to NF (FF-NF) EGM intervals during tachycardia and baseline conducted rhythm were measured using digital calipers. Events with uncertain tachycardia rhythm mechanism were excluded.
Results
Ninety-five subjects were included. Mean FF-NF interval during tachycardia was significantly lower during SVT than VT (25.8 ± 12.0 ms vs 91.0 ± 37.2 ms; P <.001). Participants with LBBB (n = 22) and RBBB (n = 21) had significantly lower mean FF-NF intervals during SVT compared with VT (LBBB 25.6 ± 7.26 ms vs 93.1 ± 41.5 ms; P <.001; RBBB 30.0 ± 16.6 ms vs 101.7 ± 34.3 ms; P <.001). In this cohort, FF-NF interval cutoff of 100 ms was 100% specific for VT discrimination regardless of underlying QRS morphology, with sensitivity of 46%, 50%, and 38% for LBBB, RBBB, and narrow QRS, respectively.
Conclusion
Prolonged FF-NF interval on intracardiac EGM during tachycardia is a highly specific discriminator for VT, regardless of baseline QRS morphology.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1561-1565
Kapoor R, Tyagi S, Dohmen C, Oujiri J, ... Rubenstein JC, Berger M
Heart Rhythm: 30 Aug 2020; 17:1561-1565 | PMID: 32353586
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Impact:
Abstract

Lead Related Superior Vena Cava Syndrome: Management and Outcomes.

Arora Y, Carrillo RG
Background
Superior Vena Cava (SVC) syndrome includes the clinical sequalae of facial and bilateral upper extremity edema, dizziness, and occasional syncope. Historically, most cases have been associated with malignancy and treatment is palliative. However, cardiac device leads have been identified as important non-malignant causes of this syndrome. There is little data on the effectiveness of venoplasty and lead extraction in the management of these patients.
Objectives
We present our experience managing 17 patients with lead-induced SVC syndrome. A literature review suggests this may be the largest case series to date.
Methods
Data collected from January 2003 to July 2019 identified 17 cases of SVC syndrome at our tertiary center. Their outcomes were compared to a control group of non-SVC syndrome patients. A P-value of <0.05 was considered statistically significant.
Results
Of the 17 patients, 13 underwent transvenous lead extraction (TLE) and venoplasty. Three patients were treated with venoplasty alone, and 1 patient underwent surgical SVC reconstruction. In 10 patients, transvenous re-implantation was necessary. Symptom resolution was achieved in all 17 patients and confirmed at both 6 and 12 months\' follow up. There was no significant difference in the rate of complications associated with TLE for SVC syndrome versus control.
Conclusion
In patients with SVC syndrome venoplasty and lead extraction are safe and effective for resolution of symptoms and maintaining SVC patency.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 09 Sep 2020; epub ahead of print
Arora Y, Carrillo RG
Heart Rhythm: 09 Sep 2020; epub ahead of print | PMID: 32920177
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Impact:
Abstract

Calcium signaling consequences of RyR2 mutations associated with CPVT1 introduced via CRISPR/Cas9 gene editing in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs): Comparison of RyR2-R420Q, F2483I and Q4201R.

Zhang XH, Wei H, Xia Y, Morad M
Background
hiPSC-CMs created from catecholaminergic polymorphic ventricular tachycardia (CPVT1) patients have been used to study the pathology of CPVT1.
Objective
To evaluate the Ca signaling aberrancies and pharmacological sensitivities of three CRISPR/Cas9 introduced CPVT1 mutations located in different molecular domains of ryanodine receptor 2 (RyR2).
Methods
CRISPR/Cas9-engineered hiPSC-CMs carrying RyR2 mutations, R420Q, Q4201R and F2483I, were voltage-clamped and their electrophysiology, pharmacology, and Ca signaling phenotypes measured using Total internal reflection fluorescence (TIRF) microscopy.
Results
R420Q and Q4201R mutant hiPSC-CMs exhibit irregular, long-lasting, spatially wandering Ca sparks, aberrant Ca releases similar to F2483I unlike the wild type (WT) myocytes. Large sarcoplasmic reticulum (SR) Ca leaks and smaller SR Ca contents were detected in cells expressing Q4201R and F2483I, but not R420Q. Fractional Ca release and calcium-induced calcium release (CICR) gain were higher in Q4201R than in R420Q and F2483I hiPSC-CMs. JTV519 was equally effective in suppressing Ca sparks, waves and SR Ca leaks in hiPSC-CMs derived from all 3 mutant lines. Flecainide and dantrolene similarly suppressed SR Ca leaks, but were less effective in decreasing sparks frequency and durations.
Conclusion
CRISPR/Cas9 gene editing of hiPSC-CMs provides a novel approach in studying CPVT1-associated RyR2 mutations and suggests that Ca-signaling aberrancies and drug sensitivities may vary depending on the mutation site.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 11 Sep 2020; epub ahead of print
Zhang XH, Wei H, Xia Y, Morad M
Heart Rhythm: 11 Sep 2020; epub ahead of print | PMID: 32931925
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Impact:
Abstract

Effects of subcutaneous nerve stimulation with blindly inserted electrodes on ventricular rate control in a canine model of persistent atrial fibrillation.

Kusayama T, Wan J, Yuan Y, Liu X, ... Everett TH, Chen PS
Background
Subcutaneous nerve stimulation (ScNS) delivered directly to large subcutaneous nerves can be either antiarrhythmic or proarrhythmic, depending on the stimulus output.
Objective
We hypothesize that high output ScNS using blindly inserted subcutaneous electrodes can reduce ventricular rate (VR) during persistent atrial fibrillation (AF) while low output ScNS has opposite effects.
Methods
We prospectively randomized 16 male and 15 female dogs with sustained AF (> 48 hrs) induced by rapid atrial pacing into three groups (sham, 0.25 mA, 3.5 mA) for four weeks of ScNS (10 Hz, alternating 20-s On and 60-s OFF).
Results
ScNS at 3.5 mA, but not 0.25 mA or sham, significantly reduced VR and stellate ganglion nerve activity (SGNA), leading to improvement of left ventricular ejection fraction (LVEF). No differences were found between the 0.25 mA and sham groups. Histological studies showed a significant reduction of bilateral atrial fibrosis in the 3.5 mA group as compared with sham controls. Only 3.5 mA ScNS had the significant fibrosis in bilateral stellate ganglions. The growth associated protein 43 (GAP43) staining of stellate ganglions indicated the suppression of GAP43 protein expression in the 3.5 mA group. There were no significant differences of nerve sprouting among all groups. There was no interaction between sex and ScNS effects on the reduction of VR and SGNA, LVEF improvement or the results of histological studies.
Conclusion
We conclude that 3.5 mA ScNS with blindly inserted electrodes can improve VR control, reduce atrial fibrosis and partially improve LVEF in a canine model of persistent AF.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 17 Sep 2020; epub ahead of print
Kusayama T, Wan J, Yuan Y, Liu X, ... Everett TH, Chen PS
Heart Rhythm: 17 Sep 2020; epub ahead of print | PMID: 32956842
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Impact:
Abstract

Cost-effectiveness of in-home automated external defibrillators for children with cardiac conditions associated with risk of sudden cardiac death.

Haag MB, Hersh AR, Toffey DE, Sargent JA, ... Caughey AB, Balaji S
Background
Children at high risk for sudden cardiac death (SCD) (>6% over 5 years) receive an implantable cardioverter-defibrillator (ICD), but no guidelines are available for those at lower risk. For children at intermediate risk for SCD (4%-6% over 5 years), the utility and cost-effectiveness of in-home automated external defibrillators (AEDs) are unclear.
Objective
The purpose of this study was to assess the cost-effectiveness of in-home AED for children at intermediate risk for SCD.
Methods
Using hypertrophic cardiomyopathy (HCM) as the proxy disease, a theoretical cohort of 1550 ten-year-old children with HCM was followed for 69 years. Baseline annual risk of SCD was 0.8%. Outcomes were SCD, severe neurologic morbidity (SNM), cost, and quality-adjusted life-years (QALYs). Model inputs were derived from the literature, with a willingness-to-pay threshold of $100,000 per QALY.
Results
Among children at intermediate risk for SCD, in-home AED resulted in 31 fewer cases of SCD but 3 more cases of SNM. There were 319 QALYs gained. Although costs were higher by $28 million, the incremental cost-effectiveness ratio was $86,458, which is below the willingness-to-pay threshold.
Conclusion
For children at intermediate risk for SCD and HCM, in-home AED is cost-effective, resulting in fewer deaths and increased QALYS for a cost below the willingness-to-pay threshold. These findings highlight the economic benefits of in-home AED use in this population.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 30 Jul 2020; 17:1328-1334
Haag MB, Hersh AR, Toffey DE, Sargent JA, ... Caughey AB, Balaji S
Heart Rhythm: 30 Jul 2020; 17:1328-1334 | PMID: 32234558
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Impact:
Abstract

COVID-19 and cardiac arrhythmias.

Bhatla A, Mayer MM, Adusumalli S, Hyman MC, ... Marchlinski F, Deo R
Background
Early studies suggest that coronavirus disease 2019 (COVID-19) is associated with a high incidence of cardiac arrhythmias. Severe acute respiratory syndrome coronavirus 2 infection may cause injury to cardiac myocytes and increase arrhythmia risk.
Objectives
The purpose of this study was to evaluate the risk of cardiac arrest and arrhythmias including incident atrial fibrillation (AF), bradyarrhythmias, and nonsustained ventricular tachycardia (NSVT) in a large urban population hospitalized for COVID-19. We also evaluated correlations between the presence of these arrhythmias and mortality.
Methods
We reviewed the characteristics of all patients with COVID-19 admitted to our center over a 9-week period. Throughout hospitalization, we evaluated the incidence of cardiac arrests, arrhythmias, and inpatient mortality. We also used logistic regression to evaluate age, sex, race, body mass index, prevalent cardiovascular disease, diabetes, hypertension, chronic kidney disease, and intensive care unit (ICU) status as potential risk factors for each arrhythmia.
Results
Among 700 patients (mean age 50 ± 18 years; 45% men; 71% African American; 11% received ICU care), there were 9 cardiac arrests, 25 incident AF events, 9 clinically significant bradyarrhythmias, and 10 NSVTs. All cardiac arrests occurred in patients admitted to the ICU. In addition, admission to the ICU was associated with incident AF (odds ratio [OR] 4.68; 95% confidence interval [CI] 1.66-13.18) and NSVT (OR 8.92; 95% CI 1.73-46.06) after multivariable adjustment. Also, age and incident AF (OR 1.05; 95% CI 1.02-1.09) and prevalent heart failure and bradyarrhythmias (OR 9.75; 95% CI 1.95-48.65) were independently associated. Only cardiac arrests were associated with acute in-hospital mortality.
Conclusion
Cardiac arrests and arrhythmias are likely the consequence of systemic illness and not solely the direct effects of COVID-19 infection.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 30 Aug 2020; 17:1439-1444
Bhatla A, Mayer MM, Adusumalli S, Hyman MC, ... Marchlinski F, Deo R
Heart Rhythm: 30 Aug 2020; 17:1439-1444 | PMID: 32585191
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Impact:
Abstract

Periaortic ventricular tachycardia in structural heart disease: Evidence of localized reentrant mechanisms.

Nishimura T, Beaser AD, Aziz ZA, Upadhyay GA, ... Nayak HM, Tung R
Background
The mechanisms for scar-related ventricular tachycardia (VT) originating from the periaortic region remain incompletely characterized.
Objective
The purpose of this study was to map the circuits responsible for periaortic VT in high resolution.
Methods
Cases with periaortic VT (2016-2020) were analyzed to characterize the substrate and mechanisms with multielectrode mapping. Periaortic VT was defined as low-voltage and/or deceleration zones within 2 cm of the left ventriculoaortic junction with a corresponding critical site during VT.
Results
Forty-nine periaortic monomorphic VTs were analyzed in 30 patients (25% of all patients with nonischemic cardiomyopathy). Isolated periaortic substrate was observed in 27% of patients, with 73% having concomitant scar, most commonly in the mid-septum (47%). Deceleration zones were equally prevalent on the septal and lateral portions of the periaortic region (87% vs 73%; P = .19). During activation mapping of VT (tachycardia cycle length 392 ± 105 ms), localized reentrant patterns of activation (14 mm [10-17 mm] × 10 mm [7-14 mm]) were demonstrated in 63% and 37% of VTs showed centrifugal activation, consistent with a focal breakout pattern. Ninety-three percent of VTs fulfilled criteria for a reentrant mechanism. Sixty-five percent of reentrant circuits had endocardial activation gaps within the tachycardia cycle length (3-dimensional circuitry), which were associated with higher rates of recurrence as compared with 2-dimensional complete circuits at 1 year (73% vs 37%; P = .028).
Conclusion
Periaortic VTs were observed in 25% of patients with nonischemic cardiomyopathy and scar-related VT. For the first time, localized reentry confined to this anatomically challenging region was demonstrated as the predominant mechanism by high-resolution circuit activation mapping.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1271-1279
Nishimura T, Beaser AD, Aziz ZA, Upadhyay GA, ... Nayak HM, Tung R
Heart Rhythm: 30 Jul 2020; 17:1271-1279 | PMID: 32325198
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Impact:
Abstract

Atrial Arrhythmias and Patient-Reported Outcomes in Adults with Congenital Heart Disease: an International Study.

Casteigt B, Samuel M, Laplante L, Shohoudi A, ... Khairy P,
Background
Atrial arrhythmias, i.e., intra-atrial reentrant tachycardia and atrial fibrillation, are a leading cause of morbidity and hospitalizations in adults with congenital heart disease (CHD). Little is known about their effect on quality of life and other patient-reported outcomes (PROs) in adults with CHD.
Objective
To assess the impact of atrial arrhythmias on PROs in adults with CHD and explore geographic variations.
Methods
Associations between atrial arrhythmias and PROs were assessed in a cross-sectional study of adults with CHD from 15 countries spanning 5 continents. A propensity-based matching weight analysis was performed to compare quality of life, perceived health status, psychological distress, sense of coherence, and illness perception in patients with and without atrial arrhythmias.
Results
A total of 4,028 adults with CHD were enrolled, 707 (17.6%) of whom had atrial arrhythmias. After applying matching weights, patients with and without atrial arrhythmias were comparable with regards to age (mean 40.1 versus 40.2 years), demographic variables (e.g., 52.5% versus 52.2% women), and complexity of CHD (i.e., 15.9% simple, 44.8% moderate, and 39.2% complex in both groups). Patients with atrial arrhythmias had significantly worse PRO scores with respect to quality of life, perceived health status, psychological distress (i.e., depression), and illness perception. A summary score that combines all PRO measures was significantly lower in patients with atrial arrhythmias (-3.3%, P=0.0006). Differences in PROs were consistent across geographic regions.
Conclusion
Atrial arrhythmias in adults with CHD are associated with an adverse impact on a broad range of PROs consistently across various geographic regions.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 18 Sep 2020; epub ahead of print
Casteigt B, Samuel M, Laplante L, Shohoudi A, ... Khairy P,
Heart Rhythm: 18 Sep 2020; epub ahead of print | PMID: 32961334
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Impact:
Abstract

Usefulness of positive T wave in lead aVR in predicting arrhythmic events and mortality in patients with hypertrophic cardiomyopathy.

Ekizler FA, Cay S, Ozeke O, Tak BT, ... Tufekcioglu O, Aras D
Background
Positive T wave in lead aVR (TaVR) has been associated with increased risk of adverse events in patients with various cardiovascular diseases.
Objective
The purpose of this study was to investigate the prevalence and prognostic significance of positive TaVR in patients with hypertrophic cardiomyopathy (HCM).
Methods
This study investigated 421 consecutive patients with HCM (177 women; age 51.1 ± 14.9 years). Admission electrocardiogram was examined for the presence of a positive TaVR. The primary endpoint was defined as a composite of major arrhythmic events (MAEs), which included sudden cardiac death, sustained ventricular tachycardia or fibrillation, or appropriate implantable cardioverter-defibrillator therapy. Cardiovascular mortality and all-cause death were evaluated as secondary endpoints.
Results
During median follow-up period of 6.0 years (interquartile range 4.0-11.6 years), 53 patients (12.6%) experienced the primary endpoint. On multivariable competing analysis, after adjusting for other confounding factors, the presence of positive TaVR was found to be an independent and strong predictor of the primary composite endpoint. Time-dependent receiver operating characteristic analysis, net reclassification index, and integrated discrimination improvement showed that the addition of positive TaVR to conventional HCM risk factors improved prediction of arrhythmic events. However, in subgroup analysis, a positive TaVR lost statistical significance in patients with apical HCM but remained significant in patients with all other hypertrophy patterns.
Conclusion
Positive TaVR is associated with MAE in HCM patients, independent of and incremental to traditional risk factors.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1312-1319
Ekizler FA, Cay S, Ozeke O, Tak BT, ... Tufekcioglu O, Aras D
Heart Rhythm: 30 Jul 2020; 17:1312-1319 | PMID: 32302704
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Abstract

Genetic testing in Polynesian long QT syndrome probands reveals a lower diagnostic yield and an increased prevalence of rare variants.

Winbo A, Earle N, Marcondes L, Crawford J, ... Hayes I, Skinner JR
Background
New Zealand has a multiethnic population and a national cardiac inherited disease registry (Cardiac Inherited Disease Registry New Zealand [CIDRNZ]). Ancestry is reflected in the spectrum and prevalence of genetic variants in long QT syndrome (LQTS).
Objective
The purpose of this study was to study the genetic testing yield and mutation spectrum of CIDRNZ LQTS probands stratified by self-identified ethnicity.
Methods
A 15-year retrospective review of clinical CIDRNZ LQTS probands with a Schwartz score of ≥2 who had undergone genetic testing was performed.
Results
Of the 264 included LQTS probands, 160 (61%) reported as European, 79 (30%) NZ Māori and Pacific peoples (Polynesian), and 25 (9%) Other ethnicities, with comparable clinical characteristics across ethnic groups (cardiac events in 72%; age at presentation 28±19 years; corrected QT interval 512±55 ms). Despite comparable testing (5.3±1.4 LQTS genes), a class III-V LQTS variant was identified in 35% of Polynesian probands as compared with 63% of European and 72% of Other probands (P<.0001). Among variant-positive CIDRNZ LQTS probands (n=148), Polynesians were more likely to have non-missense variants (57% vs 39% and 25% in probands of European and Other ethnicity, respectively; P=.005) as well as long QT syndrome type 1-3 variants not reported elsewhere (71% vs European 22% and Other 28%; P<.0001). Variants found in multiple probands were more likely to be shared within the same ethnic group; P<.01).
Conclusion
Genetic testing of Polynesian LQTS probands has a lower diagnostic yield, despite comparable testing and clinical disease severity. Rare LQTS variants are more common in Polynesian LQTS probands. These data emphasize the importance of increasing the knowledge of genetic variation in the Polynesian population.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1304-1311
Winbo A, Earle N, Marcondes L, Crawford J, ... Hayes I, Skinner JR
Heart Rhythm: 30 Jul 2020; 17:1304-1311 | PMID: 32229296
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Abstract

Altered heart rate variability in angiotensin II-mediated hypertension is associated with impaired autonomic nervous system signaling and intrinsic sinoatrial node dysfunction.

Dorey TW, Moghtadaei M, Rose RA
Background
Hypertensive heart disease is associated with sinoatrial node (SAN) dysfunction and reductions in heart rate variability (HRV). Alterations in HRV could occur in association with changes in autonomic nervous system (ANS) activity, changes in SAN function and responsiveness to ANS agonists, or both. These relationships are unclear.
Objective
The purpose of this study was to investigate the roles of ANS signaling, intrinsic SAN function, and changes in HRV in a mouse model of angiotensin II (AngII)-mediated hypertensive heart disease.
Methods
Mice were treated with saline or AngII (2.5 mg/(kg⋅d)) for 3 weeks. ANS activity was assessed through HRV analysis of electrocardiograms collected in vivo by telemetry as well as direct recordings of vagal nerve activity and renal sympathetic nerve activity from anesthetized mice. The effects of the ANS agonists isoproterenol and carbachol on SAN function and beating interval variability were assessed from electrogram recordings in intact isolated atrial preparations and from spontaneous action potential recordings in isolated SAN myocytes.
Results
Time and frequency domain analysis demonstrates that mice infused with AngII had reduced HRV. AngII-infused mice had elevated renal sympathetic nerve activity while resting vagal nerve activity was unchanged. AngII caused an increase in SAN beating interval variability in isolated atrial preparations and isolated SAN myocytes. Furthermore, isolated atrial preparations and SAN myocytes from AngII-infused mice had impaired responses to both isoproterenol and carbachol.
Conclusion
Reduced HRV in hypertension occurs in association with altered sympathovagal balance as well as intrinsic SAN dysfunction and reduced responsiveness of SAN myocytes to ANS agonists.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1360-1370
Dorey TW, Moghtadaei M, Rose RA
Heart Rhythm: 30 Jul 2020; 17:1360-1370 | PMID: 32224266
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Impact:
Abstract

Cardiac venous injuries: Procedural profiles and outcomes during left ventricular lead placement for cardiac resynchronization therapy.

Chahine J, Baranowski B, Tarakji K, Gad MM, ... Wazni O, Hussein AA
Background
Injury to the cardiac venous structures can complicate left ventricular lead placement for cardiac resynchronization therapy (CRT). Little is known about the outcomes of coronary sinus (CS) dissection with or without perforation.
Objective
The purpose of this study was to determine the outcomes in patients who had a CS injury during CRT implantation.
Methods
All patients undergoing procedures for CRT implantation at the Cleveland Clinic (2001-2018) were enrolled in a prospectively maintained registry for procedural profiles and complications. All patients with cardiac venous injuries during the procedures were included.
Results
CS injury occurred in 35 of 5011 patients (0.7%; 6 perforations (17.1%), 29 dissections without perforation (82.9%)). In patients with dissection in the absence of perforation, attempts at CS lead placement after dissection were successful in 21 of 29 patients (72.4%). In those with perforation (n=6, 17.1%), CS lead placement was successful in one of them (16.7%). Cardiac tamponade occurred in 2 patients (5.7%), and the procedure was aborted in both of them. Overall, CS lead placement failed in 13 patients (37%) but 9 (25.7%) underwent subsequent CRT with CS lead placement (n=6, 17.1%; median 58 days later) or epicardial leads (n=3, 8.6%). Three of the remaining 4 patients (8.6%) refused to undergo further procedures, and the fourth (2.9%) died of a complicated course.
Conclusion
CS injury is not common during CRT implantation procedures and did not preclude successful lead placement in 23 of 35 patients (65.7%) during the index procedure and 6 of 6 (100%) during the subsequent attempted procedures. A low rate of mortality was observed in such patients, but CS injury was associated with increased morbidity.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 30 Jul 2020; 17:1298-1303
Chahine J, Baranowski B, Tarakji K, Gad MM, ... Wazni O, Hussein AA
Heart Rhythm: 30 Jul 2020; 17:1298-1303 | PMID: 32205298
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Impact:
Abstract

Impact of interruptions in radiofrequency energy delivery on lesion characteristics.

Friedman DJ, Overmann JA, Fish JM, Gaeta SA, ... Thao R, Piccini JP
Background
During catheter ablation, delivery of radiofrequency (RF) energy to a target site is sometimes interrupted by catheter instability and clinical factors. The impact of interruption of RF delivery on lesion characteristics has not been characterized.
Objective
The purpose of this study was to determine the impact of interruption of RF application on lesion size.
Methods
Forty-two RF ablation lesions (21 left ventricle, 21 right ventricle) were created in the ventricles of 6 swine using power control mode (30 W; target contact force 15g) with 1 of 3 conditions: 15-second ablation (15s), 30-second ablation (30s), or two 15-second ablations (15s×2) at the same site separated by a 2-minute pause.
Results
Lesion volume was significantly larger for 30s lesions (501 ± 146 mm) compared to both 15s×2 (314 ± 98 mm) and 15s (242 ± 104 mm) lesions (P <.001 for both pairwise comparisons). Compared to 15s lesions, lesion volume was numerically greater for 15s×2 lesions, but this did not reach statistical significance (P = .087). Differences in lesion volume between 30s and 15s×2 lesions were driven mainly by differences in lesion width (10.7 ± 1.1 mm vs 9.1 ± 1.7 mm; P = .04) rather than depth (9 ± 1.2 mm vs 8.4 ± 1.2 mm; P = .29). There were no differences in mean contact force by group. There was no difference in total force-time integral for the 30s and 15s×2 lesion groups [median 444 (interquartile range 312) g∙s vs 380 (164) g∙s; P = 1].
Conclusion
Compared to lesions resulting from continuous RF ablation, lesions resulting from interrupted ablation have a smaller overall lesion volume, predominantly due to smaller lesion width. These data suggest that if disruption in energy delivery occurs, lesions may need closer spacing to avoid gaps.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1354-1359
Friedman DJ, Overmann JA, Fish JM, Gaeta SA, ... Thao R, Piccini JP
Heart Rhythm: 30 Jul 2020; 17:1354-1359 | PMID: 32200047
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Impact:
Abstract

Novel risk calculator performance in athletes with arrhythmogenic right ventricular cardiomyopathy.

Gasperetti A, Dello Russo A, Busana M, Dessanai M, ... Tondo C, Casella M
Background
Disease progression and ventricular arrhythmias (VAs) in arrhythmogenic right ventricular cardiomyopathy (ARVC) are correlated with physical exercise, and clinical detraining and avoidance of competitive sport practice are suggested for ARVC patients. An algorithm assessing primary arrhythmic risk in ARVC patients was recently developed by Cadrin-Tourigny et al. Data regarding its transferability to athletes are lacking.
Objective
The purpose of this study was to assess the reliability of the Cadrin-Tourigny risk prediction algorithm in a cohort of athletes with ARVC and to describe the impact of clinical detraining on disease progression.
Methods
All athletes undergoing clinical detraining after ARVC diagnosis at our institution were enrolled. Baseline and follow-up clinical characteristics and data on VA events occurring during follow-up were collected. The Cadrin-Tourigny algorithm was used to calculate the a priori predicted VA risk, which was compared with the observed outcomes.
Results
Twenty-five athletes (age 36.1 ± 14.0 years; 80% male) with definite ARVC who were undergoing clinical detraining were enrolled. Over median (interquartile range) follow-up of 5.3 (3.2-6.6) years, a reduction in premature ventricular complex (PVC) burden (P = .001) was assessed, and 10 VA events (40%) were recorded. The a priori algorithm-predicted risk seemed to fit with the observed cohort arrhythmic risk [mean observed-predicted risk difference over 5 years -0.85% (interquartile range -4.8% to +3.1%); P = .85]. At 1-year follow-up, 11 patients (44%) had an improved stress ECG response, and no significant changes in right ventricular ejection fraction were observed.
Conclusion
Clinical detraining is associated with PVC burden reduction in athletes with ARVC. The novel risk prediction algorithm does not seem to require any correction for its application to ARVC athletes.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1251-1259
Gasperetti A, Dello Russo A, Busana M, Dessanai M, ... Tondo C, Casella M
Heart Rhythm: 30 Jul 2020; 17:1251-1259 | PMID: 32200046
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Impact:
Abstract

A novel 9-partition method using fluoroscopic images for guiding left bundle branch pacing.

Jiang H, Hou X, Qian Z, Wang Y, ... Li K, Zou J
Background
Left bundle branch (LBB) pacing is a novel pacing modality, but there is no standard fluoroscopic methodology.
Objectives
This study aimed to analyze the characteristics of His bundle (HB) and LBB pacing lead locations and establish a method to guide LBB pacing using fluoroscopic images.
Methods
Seventy patients who underwent HB or LBB pacing were enrolled. The fluoroscopic image was recorded, and ventricular contraction ring in the right anterior oblique 30° projection was determined. The region between the apex and the ventricular contraction ring was divided into 9 partitions. All patients underwent postoperative computed tomography to confirm components of the ventricular contraction ring and to measure the distance from the lead tip to the junction of the noncoronary aortic cusp and right coronary cusp.
Results
HB and LBB pacing leads were successfully implanted in 11 and 35 patients, respectively. All HB pacing leads were distributed in the second partition, and 94.3% (33/35) of LBB pacing leads were in the junctional area of second and fifth partitions. The computed tomography image confirmed that the ventricular contraction ring was composed of cardiac valves. The distance from the lead tip to the junction of the noncoronary cusp and right coronary cusp of LBB and HB pacing leads was 3.8 ± 0.6 and 1.9 ± 0.2 cm, respectively. Under the guidance of the 9-partition method, the success rate of LBB pacing in 30 prospective patients increased from 58.3% (35/60) to 83.3% (25/30) (P = .03). The fluoroscopy time and the number of screwing sites also significantly decreased.
Conclusion
The distributions of HB and LBB pacing leads exhibited unique imaging characteristics. A new 9-partition method is useful to guide successful LBB pacing.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1759-1767
Jiang H, Hou X, Qian Z, Wang Y, ... Li K, Zou J
Heart Rhythm: 29 Sep 2020; 17:1759-1767 | PMID: 32417259
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Impact:
Abstract

Direct comparison of a novel antitachycardia pacing algorithm against present methods using virtual patient modeling.

Swenson DJ, Taepke RT, Blauer JJE, Kwan E, ... DeGroot P, Ranjan R
Background
Antitachycardia pacing (ATP) success rates as low as 50% for fast ventricular tachycardias (VTs) have been reported providing an opportunity for improved ATP to decrease shocks.
Objective
The purpose of this study was to determine how a new automated antitachycardia pacing (AATP) therapy would perform compared with traditional burst ATP using computer modeling to conduct a virtual study.
Methods
Virtual patient scenarios were constructed from magnetic resonance imaging and electrophysiological (EP) data. Cardiac EP simulation software (CARPEntry) was used to generate reentrant VT. Simulated VT exit sites were physician adjudicated against corresponding clinical 12-lead electrocardiograms. Burst ATP comprised 3 sequences of 8 pulses at 88% of VT cycle length, with each sequence decremented by 10 ms. AATP was limited to 3 sequences, with each sequence learning from the previous sequences.
Results
Two hundred fifty-nine unique ATP scenarios were generated from 7 unique scarred hearts. Burst ATP terminated 145 of 259 VTs (56%) and accelerated 2.0%. AATP terminated 189 of 259 VTs (73%) with the same acceleration rate. The 2 dominant ATP failure mechanisms were identified as (1) insufficient prematurity to close the excitable gap; and (2) failure to reach the critical isthmus of the VT. AATP reduced failures in these categories from 101 to 63 (44% reduction) without increasing acceleration.
Conclusion
AATP successfully adapted ATP sequences to terminate VT episodes that burst ATP failed to terminate. AATP was successful with complex scar geometries and EP heterogeneity as seen in the real world.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1602-1608
Swenson DJ, Taepke RT, Blauer JJE, Kwan E, ... DeGroot P, Ranjan R
Heart Rhythm: 30 Aug 2020; 17:1602-1608 | PMID: 32438017
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Impact:
Abstract

Cardiovascular autonomic reflex function after bilateral cardiac sympathetic denervation for ventricular arrhythmias.

Dusi V, Shahabi L, Lapidus RC, Sorg JM, ... Khalsa SS, Ajijola OA
Background
Bilateral cardiac sympathetic denervation (BCSD) is an effective therapy for ventricular arrhythmias (VAs) in cardiomyopathies (CMPs). After BCSD, residual autonomic nervous system (ANS) function is unknown.
Objective
The purpose of this study was to assess ANS responses in patients with CMP before and after BCSD as compared with demographically matched healthy controls.
Methods
Patients with CMP undergoing BCSD and matched healthy controls were recruited. Noninvasive measures-finger cuff beat-to-beat blood pressure (BP), electrocardiography, palmar electrodermal activity (EDA), and finger pulse volume (FPV)-were obtained at rest and during autonomic stressors-posture change, handgrip, and mental stress. Maximal as well as specific responses to stressors were compared.
Results
Eighteen patients with CMP (mean age 54 ± 14 years; 16 men, 89%; left ventricular ejection fraction 36% ± 14%) with refractory VAs and 8 matched healthy controls were studied; 9 patients with CMP underwent testing before and after (median 28 days) BCSD, with comparable ongoing medication. Before BCSD, patients with CMP (n = 13) had lower resting systolic BP and FPV than did healthy controls (P < .01). Maximal FPV and systolic BP reflex responses, expressed as percent change were similar, while diastolic BP, mean BP, and EDA responses were blunted. After BCSD, resting measurements were unchanged relative to presurgical baseline (n = 9). EDA responses to stressors were abolished, confirming BCSD, while maximal FPV and BP responses were preserved. Diastolic BP, mean BP, and FPV responses to orthostatic challenge pointed toward a better tolerance of active standing after BCSD as compared with before. Responses to other stressors remained unchanged.
Conclusion
Patients with CMP and refractory VAs on optimal medical therapy have detectable but blunted adrenergic responses, which are not disrupted by BCSD.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1320-1327
Dusi V, Shahabi L, Lapidus RC, Sorg JM, ... Khalsa SS, Ajijola OA
Heart Rhythm: 30 Jul 2020; 17:1320-1327 | PMID: 32325196
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Impact:
Abstract

Guidance for cardiac electrophysiology during the COVID-19 pandemic from the Heart Rhythm Society COVID-19 Task Force; Electrophysiology Section of the American College of Cardiology; and the Electrocardiography and Arrhythmias Committee of the Council on Clinical Cardiology, American Heart Association.

Lakkireddy DR, Chung MK, Gopinathannair R, Patton KK, ... Wang PJ, Russo AM

Coronavirus disease 2019 (COVID-19) is a global pandemic that is wreaking havoc on the health and economy of much of human civilization. Electrophysiologists have been impacted personally and professionally by this global catastrophe. In this joint article from representatives of the Heart Rhythm Society, the American College of Cardiology, and the American Heart Association, we identify the potential risks of exposure to patients, allied healthcare staff, industry representatives, and hospital administrators. We also describe the impact of COVID-19 on cardiac arrhythmias and methods of triage based on acuity and patient comorbidities. We provide guidance for managing invasive and noninvasive electrophysiology procedures, clinic visits, and cardiac device interrogations. In addition, we discuss resource conservation and the role of telemedicine in remote patient care along with management strategies for affected patients.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 30 Aug 2020; 17:e233-e241
Lakkireddy DR, Chung MK, Gopinathannair R, Patton KK, ... Wang PJ, Russo AM
Heart Rhythm: 30 Aug 2020; 17:e233-e241 | PMID: 32247013
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Abstract

Outcomes of subcutaneous implantable cardioverter-defibrillator in dialysis patients: Results from the S-ICD post-approval study.

El-Chami MF, Burke MC, Herre JM, Shah MH, ... Carter N, Gold MR
Background
Patients with chronic renal disease on hemodialysis (HD) have limited vascular access and are at high risk of bacteremia. The subcutaneous implantable cardioverter-defibrillator (S-ICD) avoids vascular access, so it may be advantageous in this patient population.
Objective
The purpose of this study was to report outcomes of patients with end-stage renal disease enrolled in the multicenter S-ICD post-approval study (PAS).
Methods
S-ICD PAS patients were stratified on the basis of the presence (group 1) or absence (group 2) of HD at the time of implantation. Baseline demographic and clinical characteristics were collected. Perioperative and intermediate-term outcomes 365 days postimplantation were compared between the 2 groups.
Results
There were 220 patients on HD (13.4%) at the time of implantation out of 1637 patients enrolled in the S-ICD PAS. Patients on HD (group 1) were older (57.4 ± 13.2 years vs 52.5 ± 15.2 years; P < .0001), more likely to be of African descent (48.6% vs 25.1%; P < .0001), and had lower ejection fraction (28.6% ± 11.3% vs 32.6% ± 14.9%; P < .0001) as compared with patients not on HD (group 2). Group 1 had more comorbidities and mortality was higher (17.4% vs 3.7%) than did group 2. The rate of complications calculated using the Kaplan-Meier estimate did not differ between the 2 groups (overall P = .9169), with a 1-year rate of 7.9% and 7.7% for groups 1 and 2, respectively. The rate of appropriate shocks was significantly higher in group 1 (Kaplan-Meier analysis, P = .0003), as was inappropriate shocks (P = .0137).
Conclusion
S-ICD is associated with similar adverse event rates but a higher risk of inappropriate and appropriate therapy in dialysis patients than in nondialysis patients.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1566-1574
El-Chami MF, Burke MC, Herre JM, Shah MH, ... Carter N, Gold MR
Heart Rhythm: 30 Aug 2020; 17:1566-1574 | PMID: 32376304
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Abstract

Sudden cardiac arrest with shockable rhythm in patients with heart failure.

Woolcott OO, Reinier K, Uy-Evanado A, Nichols GA, ... Jui J, Chugh SS
Background
Patients with shockable sudden cardiac arrest (SCA; ventricular fibrillation/tachycardia) have significantly better resuscitation outcomes than do those with nonshockable rhythm (pulseless electrical activity/asystole). Heart failure (HF) increases the risk of SCA, but presenting rhythms have not been previously evaluated.
Objective
We hypothesized that based on unique characteristics, HFpEF (HF with preserved ejection fraction; left ventricular ejection fraction [LVEF] ≥50%), bHFpEF (HF with borderline preserved ejection fraction; LVEF >40% and <50%), and HFrEF (HF with reduced ejection fraction; LVEF ≤40%) manifest differences in presenting rhythm during SCA.
Methods
Consecutive cases of SCA with HF (age ≥18 years) were ascertained in the Oregon Sudden Unexpected Death Study (2002-2019). LVEF was obtained from echocardiograms performed before and unrelated to the SCA event. Presenting rhythms were identified from first responder reports. Logistic regression was used to evaluate the independent association of presenting rhythm with HF subtype.
Results
Of 648 subjects with HF and SCA (median age 72 years; interquartile range 62-81 years), 274 had HFrEF (23.4% female), 92 had bHFpEF (35.9% female), and 282 had HFpEF (42.5% female). The rates of shockable rhythms were 44.5% (n = 122), 48.9% (n = 45), and 27.0% (n = 76) for HFrEF, bHFpEF, and HFpEF, respectively (P < .001). Compared with HFpEF, the adjusted odds ratios for shockable rhythm were 1.86 (95% confidence interval 1.27-2.74; P = .002) in HFrEF and 2.26 (95% CI 1.35-3.77; P = .002) in bHFpEF. The rates of survival to hospital discharge were 10.6% (n = 29) in HFrEF, 22.8% (n = 21) in bHFpEF, and 9.9% (n = 28) in HFpEF (P = .003).
Conclusion
The rates of shockable rhythm during SCA depend on the HF clinical subtype. Patients with bHFpEF had the highest likelihood of shockable rhythm, correlating with the highest rates of survival.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1672-1678
Woolcott OO, Reinier K, Uy-Evanado A, Nichols GA, ... Jui J, Chugh SS
Heart Rhythm: 29 Sep 2020; 17:1672-1678 | PMID: 32504821
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Abstract

Differentiating Hereditary Arrhythmogenic Right Ventricular Cardiomyopathy from Cardiac Sarcoidosis Fulfilling 2010 ARVC Task Force Criteria.

Gasperetti A, Rossi V, Chiodini A, Casella M, ... Duru F, Saguner AM
Background
Cardiac sarcoidosis (CS) may resemble the clinical presentation of arrhythmogenic right ventricular cardiomyopathy (ARVC).
Objective
goal of our study was identification of clinical variables to better discriminate between patients with genetically-determined ARVC and CS fulfilling definite ARVC 2010 TFC.
Methods
In this multicenter study, 10 patients with CS fulfilling definite 2010 ARVC TFC were age-and gender matched with 10 genetically-proven ARVC patients. A cardiac 18F-FDG PET-scan was required to be included in this study.
Results
The 2010 ARVC TFC did not reliably differentiate between the two diseases. CS patients presented with longer PR-intervals, advanced AVB, and a longer QRS-duration (p <0.001; and p=0.009, respectively), while T wave inversions (TWI) in peripheral leads were more common in ARVC (p=0.009). CS patients presented with more extensive LV involvement and a lower LVEF, while ARVC patients had a larger RVOT (p=0.044). PET scan positivity was only present in CS patients (90% vs 0%).
Conclusion
The 2010 TFC do not reliably differentiate between CS patients fulfilling 2010 TFC and hereditary ARVC. A prolonged PR interval, advanced AVB, longer QRS duration, RV apical involvement, a reduced LVEF, and a positive 18F-FDG PET scan should raise the suspicion of CS, whereas larger RVOT dimensions and peripheral TWI favor the diagnosis of hereditary ARVC.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 21 Sep 2020; epub ahead of print
Gasperetti A, Rossi V, Chiodini A, Casella M, ... Duru F, Saguner AM
Heart Rhythm: 21 Sep 2020; epub ahead of print | PMID: 32976989
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Abstract

Risks and outcomes of gastrointestinal malignancies in anticoagulated atrial fibrillation patients experiencing gastrointestinal bleeding: A nationwide cohort study.

Chang TY, Chan YH, Chiang CE, Lin YJ, ... Chen SA, Chao TF
Background
Oral anticoagulants (OACs) may serve as a \"screening test\" for gastrointestinal (GI) tract malignancies through the clinical presentation of bleeding.
Objective
The purpose of this study was to investigate the 1-year incidence and predictors of GI cancer after GI bleeding among atrial fibrillation (AF) patients treated with warfarin or non-vitamin K antagonist oral anticoagulants (NOACs). The risks of mortality after GI cancers between patients receiving warfarin and those receiving NOACs were compared.
Methods
A total of 10,845 anticoagulated AF patients hospitalized due to GI bleeding without a previous history of GI cancer were identified from the Taiwan National Health Insurance Research Database. Patients were followed-up for incident GI cancers for up to 1 year.
Results
Within 1 year after GI bleeding, 290 patients (2.67%) were diagnosed with GI tract cancer. More patients treated with NOACs were diagnosed with GI cancer than those treated with warfarin (3.87% vs 2.44%; P <.001; odds ratio [OR] 1.606; P <.001). Age (OR 1.025 per 1-year increment) and male sex (OR 1.356) were associated with the diagnosis of GI cancer. Among patients diagnosed with GI cancer, 45.2% died within 1 year. The risk of mortality was lower in patients treated with NOACs than in those treated with warfarin (23.5% vs 51.8%; adjusted hazard ratio 0.441; P <.001).
Conclusion
Incident GI cancers were diagnosed in 1 of 37 AF patients at 1 year after OAC-related GI bleeding and were more common among patients treated with NOACs (1/26) compared to warfarin (1/41). Detailed examinations for occult GI cancers are necessary, especially among elderly males.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1745-1751
Chang TY, Chan YH, Chiang CE, Lin YJ, ... Chen SA, Chao TF
Heart Rhythm: 29 Sep 2020; 17:1745-1751 | PMID: 32470625
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Abstract

Durability of posterior wall isolation after catheter ablation among patients with recurrent atrial fibrillation.

Markman TM, Hyman MC, Kumareswaran R, Arkles JS, ... Marchlinski FE, Nazarian S
Background
Electrical posterior wall isolation (PWI) is increasingly being used for the treatment of patients with atrial fibrillation (AF). Few data exist on the durability of PWI using current technology.
Objective
The purpose of this study was to characterize the frequency and location of posterior wall reconnection at the time of repeat catheter ablation for AF.
Methods
We performed a single-center retrospective cohort study of 50 patients undergoing repeat AF ablation after previous PWI. Durability of PWI was assessed at the time of repeat ablation based on posterior wall entrance and exit block. Sites of posterior wall reconnection were characterized based on review of recorded electrical signals and electroanatomic maps.
Results
At the time of repeat ablation, mean age was 67 ± 10 years, 31 of 50 patients had persistent AF, and mean CHADS-VASc score was 3.0 ± 1.8. Of the 50 patients, 30 had durable PWI at repeat ablation, 1.4 ± 1.6 years after the index procedure. Patients with posterior wall reconnection required repeat ablation earlier (0.9 ± 0.6 years vs1.8 ± 1.9 years from index PWI; P = .048) and were more likely to have atypical atrial flutter (55% vs 27%; P = .043). Among patients with posterior wall reconnection, the roof was the most common site of reconnection (14/20), and 12 patients had multiple regions of reconnection noted.
Conclusion
Posterior wall reconnection is noted in 40% of patients undergoing repeat ablation after an index PWI. The roof of the left atrium is the most common site of posterior wall reconnection.

Copyright © 2020 Heart Rhythm Society. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1740-1744
Markman TM, Hyman MC, Kumareswaran R, Arkles JS, ... Marchlinski FE, Nazarian S
Heart Rhythm: 29 Sep 2020; 17:1740-1744 | PMID: 32389682
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Abstract

Long-term outcomes of ventricular tachycardia substrate ablation incorporating hidden slow conduction analysis.

Acosta J, Soto-Iglesias D, Jáuregui B, Armenta JF, ... Mont L, Berruezo A
Background
Ventricular tachycardia substrate ablation (VTSA) incorporating hidden slow conduction (HSC) analysis allows further arrhythmic substrate identification.
Objective
The purpose of this study was to analyze whether the elimination of HSC electrograms (HSC-EGMs) during VTSA results in better short- and long-term outcomes.
Methods
Consecutive patients (N = 70; 63% ischemic; mean age 64 ± 14.6 years) undergoing VTSA were prospectively included. Bipolar EGMs with >3 deflections and duration <133 ms were considered as potential HSC-EGMs. Whenever a potential HSC-EGM was identified, double or triple ventricular extrastimuli were delivered. If a local potential showed up as a delayed component, it was annotated as HSC-EGM. Ablation was delivered at conducting channel entrances and HSC-EGMs. Radiofrequency time, ventricular tachycardia (VT) inducibility after VTSA, and VT/ventricular fibrillation recurrence at 24 months after the procedure were compared with data from a historical control group.
Results
A total of 5076 EGMs were analyzed; 1029 (20.2%) qualified as potential HSC-EGMs, and 475 of them were tagged as HSC-EGMs. Scars in patients with HSC-EGMs (n = 43 [61.4%]) were smaller (32.2 [17-58] cm vs 85 [41-92.4] cm; P = .006) and more heterogeneous (core/scar area ratio 0.15 [0.05-0.44] vs 0.44 [0.33-0.57]; P = .017); 32.4% of HSC-EGMs were located in normal voltage tissue. Patients undergoing VTSA incorporating HSC analysis required less radiofrequency time (15.6 [8-23.1] vs 23.9 [14.9-30.8]; P < .001) and had a lower rate of VT inducibility after VTSA (28.6% vs 52.9%; P = .003) than did the historical controls. Patients undergoing VTSA incorporating HSC analysis showed a higher 2-year VT/ventricular fibrillation-free survival (75.7% vs 58.8%; log-rank, P = .046) after VTSA.
Conclusion
VTSA incorporating HSC analysis allowed further arrhythmic substrate identification (especially in the border zone and normal voltage areas) and was associated with increased VTSA efficiency and better short- and long-term outcomes.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1696-1703
Acosta J, Soto-Iglesias D, Jáuregui B, Armenta JF, ... Mont L, Berruezo A
Heart Rhythm: 29 Sep 2020; 17:1696-1703 | PMID: 32417258
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Abstract

Automated electrocardiographic quantification of myocardial scar in patients undergoing primary prevention implantable cardioverter-defibrillator implantation: Association with mortality and subsequent appropriate and inappropriate therapies.

Reichlin T, Asatryan B, Vos MA, Willems R, ... Sticherling C,
Background
Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been developed to estimate myocardial scar from the 12-lead electrocardiogram.
Objective
We aimed to assess the value of an automated version of the Selvester QRS score for the prediction of implantable cardioverter-defibrillator (ICD) therapy and death in patients undergoing primary prevention ICD implantation.
Methods
Unselected patients undergoing primary prevention ICD implantation were included in this retrospective, observational, multicenter study. The QRS score was calculated automatically from a digital standard preimplantation 12-lead electrocardiogram and was correlated to the occurrence of death and appropriate and inappropriate shocks during follow-up. Analyses were performed in groups defined by QRS duration < 130 ms vs ≥ 130 ms.
Results
Overall, 1047 patients (872 [83%] men; median age 64 years IQR [55-71]) with ischemic (648, 62%) or nonischemic (399, 38%) cardiomyopathy were included. The median QRS duration was 123 ms (interquartile range [IQR] 111-157 ms), and the median QRS score was 5 (IQR 2-8). The QRS duration was <130 ms in 59% and ≥130 ms in 41%. During a median follow-up of 45 months (IQR 24-72 months), a QRS score of ≥5 was independently associated with a significantly higher risk of mortality (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.05-2.66; P = .031) and appropriate (HR 1.83; 95% CI 1.07-3.14; P = .028) and inappropriate (HR 2.32; 95% CI 1.04-5.17; P = .039) shocks in patients with QRS duration ≥ 130 ms. No association of the QRS score and outcome was observed in patients with QRS duration < 130 ms (P > .05).
Conclusion
The automatically calculated Selvester QRS score, an indicator of myocardial scar burden, predicts mortality and appropriate and inappropriate shocks in patients undergoing primary prevention ICD implantation with a prolonged QRS duration.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1664-1671
Reichlin T, Asatryan B, Vos MA, Willems R, ... Sticherling C,
Heart Rhythm: 29 Sep 2020; 17:1664-1671 | PMID: 32428669
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Abstract

Ten-year outcomes of transcaval cardiac puncture for catheter ablation after extracardiac Fontan surgery.

Moore JP, Gallotti RG, Tran E, Perens GS, Shannon KM
Background
Although they are at lower risk, patients with previous extracardiac conduit (EC) Fontan still may require catheter ablation for supraventricular arrhythmia.
Objective
The purpose of this study was to determine the optimal approach to pulmonary venous atrium (PVA) access after EC Fontan operation.
Methods
All electrophysiological procedures requiring PVA over a 10-year period at the UCLA Medical Center were reviewed. PVA was grouped by transcaval cardiac puncture (TCP) or direct conduit puncture. Procedural characteristics and outcomes were compared.
Results
Between June 2009 and November 2019, 23 electrophysiological procedures requiring PVA access were performed in 17 EC Fontan patients (53% male; median age 25 years; interquartile range 11-34). Cavoatrial overlap was identified in 14 patients by preprocedural imaging (10 cardiac computed tomography, 4 cardiac magnetic resonance). PVA access was obtained via TCP in 11, direct conduit puncture in 6, pre-existing fenestration in 5, and pulmonary artery puncture in 1. Time to PVA was significantly shorter for TCP vs direct conduit puncture (0.2 vs 1.1 hours, respectively; P = .03). The only predictor of successful TCP was the length of cavoatrial overlap by preprocedural imaging (14 vs 3 mm; P = .02). No procedural complications occurred. No change in oxygen saturation was noted, and no evidence of residual shunting was detected by follow-up echocardiography.
Conclusion
TCP is feasible in most patients after EC Fontan surgery and can be predicted by preprocedural advanced imaging. TCP is associated with shorter time to PVA and was uncomplicated in this single-center study. Preoperative assessment of cavoatrial overlap should be considered before catheter ablation for EC Fontan.

Published by Elsevier Inc.

Heart Rhythm: 29 Sep 2020; 17:1752-1758
Moore JP, Gallotti RG, Tran E, Perens GS, Shannon KM
Heart Rhythm: 29 Sep 2020; 17:1752-1758 | PMID: 32438019
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Abstract

Use of virtual visits for the care of the arrhythmia patient.

Hu PT, Hilow H, Patel D, Eppich M, ... Wazni O, Tarakji KG
Background
Virtual visits (VVs) are a modality for delivering health care services remotely through videoconferencing tools. Data about patient and physician experience in using VVs are limited.
Objective
The purpose of this study was to assess patient and physician experience with the use of VVs in cardiac electrophysiology.
Methods
We performed a prospective survey of cardiac electrophysiology patients and physicians who participated in an outpatient VV from December 2018 to July 2019.
Results
One-hundred consecutive VVs were included. Sixty-four patients elected to complete a survey. Patients rated their experience as either excellent/very good in scheduling a VV (87%), seeing their physician of choice (100%), transmitting arrhythmia data (88%), rating their physician\'s ability to communicate (98%), asking all questions (98%), rating the level of care received (98%), paying for the cost of a VV (67%), and rating their overall level of satisfaction (98%). Thirty-eight of 64 patients (59.4%) preferred a VV for their next visit, 12 of 64 (18.8%) preferred an in-office visit, 13 of 64 (20.3%) responded that their decision for a virtual or office visit depended on indication, and 1 of 64 (1.6%) had no preference. A total of 14 cardiac electrophysiologists participated in 100 VVs. Nine visits were not included due to technical difficulty. Physician responses to survey questions were rated as excellent/very good in the ability to communicate (92%), accessing monitoring data (95%), and overall level of satisfaction (98%).
Conclusion
In our small study population, most patients and physicians prefer VVs. Convenience, cost, and reason for follow-up were important determinants that affected both patient and physician preference.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1779-1783
Hu PT, Hilow H, Patel D, Eppich M, ... Wazni O, Tarakji KG
Heart Rhythm: 29 Sep 2020; 17:1779-1783 | PMID: 32438016
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Abstract

Left cardiac sympathetic denervation reduces skin sympathetic nerve activity in patients with long QT syndrome.

Han J, Ackerman MJ, Moir C, Cai C, ... Chen PS, Cha YM
Background
Although left cardiac sympathetic denervation (LCSD) is an effective antiarrhythmic therapy for patients with long QT syndrome (LQTS), direct evidence of reduced sympathetic activity after LCSD in humans is limited.
Objective
The purpose of this study was to assess skin sympathetic nerve activity (SKNA) in patients with LQTS undergoing LCSD.
Methods
We prospectively enrolled 17 patients with LQTS who underwent LCSD between 2017 and 2019. SKNA recordings from the left arm (L-SKNA) and chest (C-SKNA) leads were performed before and after LCSD. Mean SKNA, burst activity, and nonburst activity of L-SKNA and C-SKNA were analyzed.
Results
The mean patient age was 21 ± 9 years (8 men 47%). The longest baseline corrected QT value was 497 ± 55 ms at rest and 531 ± 38 ms on exercise stress testing. Five patients (29.4%) had previous LQTS-triggered cardiac events including syncope, documented torsades de pointes, and ventricular fibrillation. In the 24 hours after LCSD, mean L-SKNA decreased from 1.25 ± 0.64 to 0.85 ± 0.33 μV (P = .005) and mean C-SKNA from 1.36 ± 0.67 to 1.05 ± 0.49 μV (P = .11). The frequency of episodes of SKNA bursts recorded from the left-arm lead (2.87 ± 1.61 bursts per minute vs 1.13 ± 0.99 bursts per minute; P < .001) and mean L-SKNA during burst (1.82 ± 0.79 μV vs 1.15 ± 0.44 μV; P < .001) and nonburst (1.09 ± 0.60 μV vs 0.75 ± 0.32 μV; P = .03) periods significantly decreased after LCSD, while the frequency of episodes of SKNA bursts recorded from the chest lead (P = .57) and mean C-SKNA during burst (P = .44) and nonburst (P = .10) periods did not change significantly. No arrhythmic events were documented after 11.9 months (range 3.0-22.2 months) of follow-up.
Conclusion
LCSD provides an inhibitory effect on cardiac sympathetic activity by suppressing burst discharge as measured by SKNA.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 29 Sep 2020; 17:1639-1645
Han J, Ackerman MJ, Moir C, Cai C, ... Chen PS, Cha YM
Heart Rhythm: 29 Sep 2020; 17:1639-1645 | PMID: 32276050
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Abstract

Improvement in sudden cardiac death risk prediction by the enhanced American College of Cardiology/American Heart Association strategy in Chinese patients with hypertrophic cardiomyopathy.

Liu J, Wu G, Zhang C, Ruan J, ... Wang J, Song L
Background
The lack of validated and effective sudden cardiac death (SCD) risk prediction methods is the biggest barrier to perform the lifesaving treatment with a prophylactic implantable cardioverter-defibrillator in Chinese patients with hypertrophic cardiomyopathy (HCM).
Objective
This study aimed to evaluate the efficacy of 3 existing SCD risk prediction methods recommended by the 2011 American College of Cardiology Foundation and American Heart Association (ACCF/AHA) guideline, the 2014 European Society of Cardiology (ESC) guideline, and the 2019 enhanced American College of Cardiology (ACC)/AHA strategy in Chinese patients with HCM.
Methods
The present study consisted of 1369 consecutive adult patients with HCM without a history of SCD events. The primary end point was a composite of SCD and equivalent events, namely, resuscitation from cardiac arrest and appropriate implantable cardioverter-defibrillator shock therapy for ventricular tachycardia or fibrillation.
Results
During follow-up of 3.2 ± 2.4 years, 39 patients reached SCD end points, of whom 26 (66.7%) were correctly predicted as those at a high risk of SCD by using methods recommended by the 2019 enhanced ACC/AHA strategy, 20 (51.3%) by the 2011 ACCF/AHA guideline, but only 5 (12.8%) by the 2014 ESC guideline. The 2019 enhanced ACC/AHA strategy showed a higher C-statistic (0.647) for SCD prediction than did the 2011 ACCF/AHA guideline (0.598) and 2014 ESC guideline (0.605) and resulted in the correct reclassification of SCD risk when compared with the 2011 ACCF/AHA guideline (net reclassification index 0.113; P = .074) and 2014 ESC guideline (net reclassification index 0.245; P = .038).
Conclusion
The 2019 enhanced ACC/AHA strategy showed better predictive performance for SCD risk stratification in Chinese patients with HCM, with a notably high sensitivity.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1658-1663
Liu J, Wu G, Zhang C, Ruan J, ... Wang J, Song L
Heart Rhythm: 29 Sep 2020; 17:1658-1663 | PMID: 32311532
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Impact:
Abstract

Comparison of cardiovascular screening in college athletes by history and physical examination with and without an electrocardiogram: Efficacy and cost.

Harmon KG, Suchsland MZ, Prutkin JM, Owens DS, ... Malik A, Drezner JA
Background
Preparticipation screening for conditions associated with sudden cardiac death (SCD) is required in college athletes. Previous cost analyses used theoretical models based on variable assumptions, but no study used real-life outcomes.
Objective
The purpose of this study was to compare disease prevalence, positive findings, and costs of 2 different screening strategies: history and physical examination alone (H&P) or with an electrocardiogram (H&P+ECG).
Methods
De-identified preparticipation data (2009-2017) from Pacific-12 Conference institutions were abstracted for cardiovascular history questions, cardiovascular physical examination, and ECG result. Secondary testing, cardiac diagnoses, return to play outcomes, and complications from testing were recorded. The costs of screening and secondary testing were based on the Centers for Medicare & Medicaid Services Physician Fee Schedule.
Results
A total of 8602 records (4955 H&P, 3647 H&P+ECG) were included. Eleven conditions associated with SCD were detected (2 H&P only, 9 H&P+ECG). The prevalence of cardiovascular conditions associated with SCD discovered with H&P alone was 0.04% (1/2454) compared to 0.24% (1/410) when ECG was added (P = .01) (odds ratio 5.17; 95% confidence interval 1.28-20.85; P = .02). Cost of screening and secondary testing with H&P alone was $130 per athlete and in the ECG-added group was $152 per athlete. The cost per diagnosis was $312,407 in the H&P group and $61,712 in the ECG-added group. There were no adverse outcomes from secondary testing or treatment.
Conclusion
H&P with the addition of ECG is 6 times more likely to detect a cardiovascular condition associated with SCD than without. The addition of ECG improves the cost efficiency per diagnosis by 5-fold and should be considered at college institutions with appropriate resources.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1649-1655
Harmon KG, Suchsland MZ, Prutkin JM, Owens DS, ... Malik A, Drezner JA
Heart Rhythm: 29 Sep 2020; 17:1649-1655 | PMID: 32380289
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Impact:
Abstract

Electrocardiographic interpretation of pacemaker algorithms enabling minimal ventricular pacing.

Mond HG

Cardiac pacing from the apex of the right ventricle has been shown to result in left ventricular dysfunction, atrial fibrillation, and increased mortality. To counter these effects, one of the strategies developed is avoidance of ventricular pacing when not necessary, using programmable algorithms to minimize ventricular pacing. Seven algorithms are available from 5 manufacturers. Four of the manufacturers have mode conversion algorithms that pace AAI(R) but, in the presence of failed atrioventricular (AV) conduction, demonstrate algorithm-offset and convert to DDD(R) with ventricular pacing. Three manufacturers do not have mode conversion but rather AV extension to encourage AV conduction. Each of these algorithms has a unique design and, when ventricular pacing is present, will regularly schedule conduction testing to encourage AV conduction and hence algorithm-onset. All of these algorithms seem to violate the rule of AV conduction by allowing the AV delay for sensed ventricular events to be longer than for ventricular paced events. The result is frequently bizarre electrocardiographic (ECG) appearances that often are unique to the company\'s algorithm but also suggest pacemaker malfunction. This review highlights and illustrates the features of these algorithms as they appear on ECG, and discusses other situations that result in unintended ventricular pacing.

Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1784-1792
Mond HG
Heart Rhythm: 29 Sep 2020; 17:1784-1792 | PMID: 32413512
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Impact:
Abstract

Ventricular tachycardia in cardiolaminopathy: Characteristics and considerations for device programming.

Sidhu K, Han L, Picard KCI, Tedrow UB, Lakdawala NK
Background
Mutations in LMNA cause an arrhythmogenic cardiomyopathy (cardiolaminopathy) with high risk of ventricular tachycardia (VT). The natural history of VT among patients with cardiolaminopathy is incompletely understood.
Objective
The purpose of this study was to determine the longitudinal burden and progression of VT, including change in tachycardia cycle length (TCL), response to antitachycardia pacing (ATP), and prognostic significance of high-burden VT (>5 episodes of VT at any device interrogation) in cardiolaminopathy patients.
Methods
Patients with cardiolaminopathy and an implantable cardioverter-defibrillator (ICD) were identified from a single-center database. Serial device interrogations and medical records were used to collect data on VT burden, TCL, and response to ATP.
Results
Cardiolaminopathy patients with primary (n = 27) or secondary prevention (n = 16) ICDs were followed for 2 years (interquartile range [IQR] 1-5). VT burden was substantially higher in patients receiving secondary prevention ICDs (28 ± 40.9 vs 3.6 ± 7.3 episodes per 100 patient-years; P <.001). ATP was highly effective (94%) at terminating VT except for short TCL (<250 ms), for which ATP failed in 60%. Among patients with recurrent VT, TCL increased by 112 ± 93.6 ms during follow-up. Inappropriate shocks were rare (0.4% of all therapies). Median time to transplantation, ventricular assist device, or death was 18 months (IQR 0.7-27.1) in patients with high-burden VT.
Conclusion
In patients with cardiolaminopathy, VT is recurrent and highly responsive to ATP, which supports the use of transvenous ICDs iteratively programmed to manage VT of various TCLs. Onset of high-burden VT indicates poor prognosis and should warrant referral to a heart failure specialist.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1704-1710
Sidhu K, Han L, Picard KCI, Tedrow UB, Lakdawala NK
Heart Rhythm: 29 Sep 2020; 17:1704-1710 | PMID: 32454220
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Abstract

QRS morphology in lead V for the rapid localization of idiopathic ventricular arrhythmias originating from the left ventricular papillary muscles: A novel electrocardiographic criterion.

Briceño DF, Santangeli P, Frankel DS, Liang JJ, ... Marchlinski FE, Schaller RD
Background
Twelve-lead electrocardiogram (ECG) criteria have been developed to identify idiopathic ventricular arrhythmias (VAs) from the left ventricular (LV) papillary muscles (PAPs), but accurate localization remains a challenge.
Objective
The purpose of this study was to develop ECG criteria for accurate localization of LV PAP VAs using lead V exclusively.
Methods
Consecutive patients undergoing mapping and ablation of VAs from the LV PAPs guided by intracardiac echocardiography from 2007 to 2018 were reviewed (study group). The QRS morphology in lead V was compared to patients with VAs with a \"right bundle branch block\" morphology from other LV locations (reference group). Patients with structural heart disease were excluded.
Results
One hundred eleven patients with LV PAP VAs (mean age 54 ± 16 years; 65% men) were identified, including 64 (55%) from the posteromedial PAP and 47 (42%) from the anterolateral PAP. The reference group included patients with VAs from the following LV locations: fascicles (n = 21), outflow tract (n = 36), ostium (n = 37), inferobasal segment (n = 12), and apex (5). PAP VAs showed 3 distinct QRS morphologies in lead V 93% of the time: Rr (53%), R with a slurred downslope (29%), and RR (11%). Sensitivity, specificity, positive predictive value, and negative predictive value for the 3 morphologies combined are 93%, 98%, 98%, and 93%, respectively. The intrinsicoid deflection of PAP VAs in lead V was shorter than that of the reference group (63 ± 13 ms vs 79 ± 24 ms; P < .001). An intrinsicoid deflection time of <74 ms best differentiated the 2 groups (sensitivity 79%; specificity 87%).
Conclusion
VAs originating from the LV PAPs manifest unique QRS morphologies in lead V, which can aid in rapid and accurate localization.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1711-1718
Briceño DF, Santangeli P, Frankel DS, Liang JJ, ... Marchlinski FE, Schaller RD
Heart Rhythm: 29 Sep 2020; 17:1711-1718 | PMID: 32454219
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Impact:
Abstract

Purkinje system hyperexcitability and ventricular arrhythmia risk in type 3 long QT syndrome.

Barake W, Giudicessi JR, Asirvatham SJ, Ackerman MJ
Background
Gain-of-function variants in the SCN5A-encoded Na1.5 sodium channel cause type 3 long QT syndrome (LQT3) and multifocal ectopic Purkinje-related premature contractions. Although the Purkinje system is uniquely sensitive to the action potential-prolonging effects of LQT3-causative variants, the existence of additional Purkinje phenotype(s) in LQT3 is unknown.
Objective
The purpose of this study was to determine the prevalence and clinical implications of frequent fascicular/Purkinje-related premature ventricular contractions (PVCs) and short-coupled ventricular arrhythmias (VAs), suggestive of Purkinje system hyperexcitability (PSH), in a single-center LQT3 cohort.
Methods
A retrospective analysis of 177 SCN5A-positive patients was performed to identify individuals with a LQT3 phenotype. Available electrocardiographic, electrophysiology study, device, and genetic data from 91 individuals with LQT3 were reviewed for evidence of presumed fascicular PVCs and short-coupled VAs. The relationship between PSH and ventricular fibrillation events was assessed by Kaplan-Meier and Cox regression analyses.
Results
Overall, 30 of 91 patients with LQT3 (33%) exhibited evidence of presumed PSH (fascicular PVCs 30 of 30 [100%]; short-coupled VAs 17 of 30 [56%]). Kaplan-Meier and Cox regression analyses demonstrated an increased risk of ventricular fibrillation events in individuals with LQT3 and PSH (log-rank, P < .03; hazard ratio 3.95; 95% confidence interval 1.15-15.7; P = .03). Interestingly, variants in the voltage-sensing domain regions of Na1.5 were more frequently observed in patients with LQT3 and PSH than those without (19 of 30 [63%] vs 9 of 61 [15%]; P < .0001).
Conclusion
This study demonstrates that a discernible Purkinje phenotype is present in one-third of LQT3 cases and increases the risk of potentially lethal VAs. Further study is needed to determine whether a distinct cellular electrophysiology phenotype underlies this phenomenon.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 29 Sep 2020; 17:1768-1776
Barake W, Giudicessi JR, Asirvatham SJ, Ackerman MJ
Heart Rhythm: 29 Sep 2020; 17:1768-1776 | PMID: 32454217
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Impact:
Abstract

Outer loop and isthmus in ventricular tachycardia circuits: Characteristics and implications.

Frontera A, Pagani S, Limite LR, Hadjis A, ... Quarteroni A, Della Bella P
Background
The isthmus of ventricular tachycardia (VT) circuits has been extensively characterized. Few data exist regarding the contribution of the outer loop (OL) to the VT circuit.
Objective
The purpose of this study was to characterize the electrophysiological properties of the OL.
Methods
Complete substrate activation mapping during sinus rhythm (SR) and full activation mapping of the VT circuit with high-density mapping were performed. Maps were analyzed mathematically to reconstruct conduction velocities (CVs) within the circuit. CV >100 cm/s was defined as normal and <50 cm/s as slow. Electrograms along the entire circuit were analyzed for fractionation, duration, and amplitude.
Results
Six postmyocardial infarction patients were enrolled. The VT circuit was a figure-of-eight reentrant circuit in 4 patients and a single-loop circuit in 2 patients. The OL exhibited a mean of 1.9 ± 0.9 and 1.6 ± 0.5 corridors of slow conduction (SC) during VT and SR, respectively. SC in the OL were longer and faster than SC in the isthmus during SR. At the OL, SC sites showed local abnormal ventricular activity in 92%, and a bipolar voltage <0.5 mV was identified in 80.7%. Of the double-loop circuits, only 1 patient had fixed lines of block as isthmus boundaries, whereas in 3 patients the circuits were at least partially functional.
Conclusion
In ischemic reentrant VT circuits, the OL contributes significantly to reentry with multiple corridors of SC. These corridors can result from structural or functional phenomena. Isthmus boundaries may correspond to functional or fixed lines of block.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1719-1728
Frontera A, Pagani S, Limite LR, Hadjis A, ... Quarteroni A, Della Bella P
Heart Rhythm: 29 Sep 2020; 17:1719-1728 | PMID: 32497763
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Impact:
Abstract

Loss of ventricular preexcitation during noninvasive testing does not exclude high-risk accessory pathways: A multicenter study of WPW in children.

Escudero CA, Ceresnak SR, Collins KK, Pass RH, ... Etheridge SP, Janson CM
Background
Abrupt loss of ventricular preexcitation on noninvasive evaluation, or nonpersistent preexcitation, in Wolff-Parkinson-White syndrome (WPW) is thought to indicate a low risk of life-threatening events.
Objective
The purpose of this study was to compare accessory pathway (AP) characteristics and occurrences of sudden cardiac arrest (SCA) and rapidly conducted preexcited atrial fibrillation (RC-AF) in patients with nonpersistent and persistent preexcitation.
Methods
Patients 21 years or younger with WPW and invasive electrophysiology study (EPS) data, SCA, or RC-AF were identified from multicenter databases. Nonpersistent preexcitation was defined as absence/sudden loss of preexcitation on electrocardiogram, Holter monitoring, or exercise stress test. RC-AF was defined as clinical preexcited atrial fibrillation with shortest preexcited R-R interval (SPERRI) ≤ 250 ms. AP effective refractory period (APERP), SPERRI at EPS , and shortest preexcited paced cycle length (SPPCL) were collected. High-risk APs were defined as APERP, SPERRI, or SPPCL ≤ 250 ms.
Results
Of 1589 patients, 244 (15%) had nonpersistent preexcitation and 1345 (85%) had persistent preexcitation. There were no differences in sex (58% vs 60% male; P=.49) or age (13.3±3.6 years vs 13.1±3.9 years; P=.43) between groups. Although APERP (344±76 ms vs 312±61 ms; P<.001) and SPPCL (394±123 ms vs 317±82 ms; P<.001) were longer in nonpersistent vs persistent preexcitation, there was no difference in SPERRI at EPS (331±71 ms vs 316±73 ms; P=.15). Nonpersistent preexcitation was associated with fewer high-risk APs (13% vs 23%; P<.001) than persistent preexcitation. Of 61 patients with SCA or RC-AF, 6 (10%) had nonpersistent preexcitation (3 SCA, 3 RC-AF).
Conclusion
Nonpersistent preexcitation was associated with fewer high-risk APs, though it did not exclude the risk of SCA or RC-AF in children with WPW.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1729-1737
Escudero CA, Ceresnak SR, Collins KK, Pass RH, ... Etheridge SP, Janson CM
Heart Rhythm: 29 Sep 2020; 17:1729-1737 | PMID: 32497761
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Impact:
Abstract

Diagnostic yield and long-term outcome of nonischemic sudden cardiac arrest survivors and their relatives: Results from a tertiary referral center.

Jacobsen EM, Hansen BL, Kjerrumgaard A, Tfelt-Hansen J, ... Bundgaard H, Winkel BG
Background
Cardiac arrest may be the first manifestation of most inherited cardiac diseases. International guidelines recommend screening of relatives of sudden cardiac arrest (SCA) survivors if an inherited cardiac disorder is suspected.
Objective
The purpose of this study was to assess the prevalence and spectrum of inherited cardiac diseases and the long-term outcome in a consecutive cohort of nonischemic SCA survivors (probands) and their relatives.
Methods
This retrospective study consecutively included probands and their relatives referred to our tertiary center for family screening between 2005 and 2018. All participants underwent a systematic workup and follow-up protocol. Data were retrieved from medical records.
Results
We included 155 probands (age 41.2 ± 15.5 years; 61% male) and 282 relatives (age 35.7 ± 18.8 years; 51% male). Mean follow-up was 7.1 years for probands and 4.4 years for relatives. We identified an inherited cardiac disease in 76 (49%) probands and 42 (15%) relatives. An implantable cardioverter-defibrillator was inserted in 147 (95%) probands and 9 (3%) relatives. During follow-up, 4 (3%) probands and 3 (1%) relatives died, and 37 probands and 2 relatives received appropriate shock therapy. All relatives received genetic counseling, and 18 (6%) relatives started pharmacologic treatment during follow-up.
Conclusion
Systematic workup of nonischemic SCA survivors and their relatives identified an inherited cardiac disease in 49% of referred probands and 15% of their relatives. The favorable long-term prognosis of diagnosed relatives probably not only reflects lower age but also the effects of early diagnosis, treatment, and follow-up. These findings support systematic workup of SCA survivors and their relatives.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 29 Sep 2020; 17:1679-1686
Jacobsen EM, Hansen BL, Kjerrumgaard A, Tfelt-Hansen J, ... Bundgaard H, Winkel BG
Heart Rhythm: 29 Sep 2020; 17:1679-1686 | PMID: 32615163
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Impact:
Abstract

Mapping and ablation of clinical spontaneous peri-mitral atrial tachycardias using an ultra-high resolution mapping system.

Miyazaki S, Hasegawa K, Yamao K, Ishikawa E, ... Iesaka Y, Tada H
Background
Peri-mitral atrial tachycardias (PMATs) are common ATs, yet the mechanisms vary.
Objective
We sought to characterize clinical spontaneous PMATs using an ultra-high resolution mapping (UHRM) system.
Methods
This study included 32 consecutive PMATs in 31 patients who underwent AT mapping/ablation using UHRM systems.
Results
Six, 10, 11, and 5 PMATs occurred in cardiac intervention-naïve (Group-A), post- lateral/posterior mitral isthmus linear ablation (Group-B), post-atrial fibrillation ablation without mitral isthmus linear ablation (Group-C), and post-cardiac surgery (Group-D) patients, respectively. Group-A tended to be older and more likely female and had sinus node or atrioventricular conduction disturbances more frequently. A 12-lead synchronous isoelectric interval was observed in 15 (46.9%) PMATs. Coronary sinus activation was proximal-to-distal or distal-to-proximal except in 3 PMATs with straight patterns owing to epicardial gaps. LA anterior/septal wall (LAASW) low voltage areas were smallest in group-B. Slow conduction areas (SCAs) were identified in 26 (81.2%) PMATs and were on the LAASW in all group-A and group-D patients. The conduction velocity in the SCAs was slowest in group-B. In group-B, all PMATs were terminated by single applications, and the gaps were located epicardially in 5/10 (50%). Anterior (n=23) or lateral/posterior (n=9) mitral isthmus linear block was successfully created without any complications in all. Twenty-five concomitant ATs among 18 (58.1%) patients were also eliminated. During 20.0[11.0-40.0] months of follow-up, 28 (90.3%) patients were free from any atrial tachyarrhythmias.
Conclusion
A UHRM-guided approach with identification of the individual tachycardia mechanism should be the preferred strategy since arrhythmia mechanisms are distinct and complex.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 28 Sep 2020; epub ahead of print
Miyazaki S, Hasegawa K, Yamao K, Ishikawa E, ... Iesaka Y, Tada H
Heart Rhythm: 28 Sep 2020; epub ahead of print | PMID: 33007441
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Impact:
Abstract

Anticoagulation for Stroke Prevention in Patients With Hypertrophic Cardiomyopathy and Atrial Fibrillation: A Review.

Nasser MF, Gandhi S, Siegel RJ, Rader F

Atrial fibrillation is the most common arrhythmia in patients with hypertrophic cardiomyopathy with a prevalence and incidence of 23% and 3.1% respectively. The risk of thromboembolism is high in patients with hypertrophic cardiomyopathy regardless of the CHADS2VASC score. This review includes five observational studies that focused on prevention of thromboembolism in patients with hypertrophic cardiomyopathy and atrial fibrillation. These papers evaluated and compared outcomes between patients on either warfarin or direct oral anticoagulants. Data showed that direct oral anticoagulants are effective and safe in this patient population and also may have a benefit over warfarin in thromboprophylaxis in patients with hypertrophic cardiomyopathy and atrial fibrillation. In conclusion, lifelong anticoagulation with warfarin is recommended to prevent thromboembolism in patients with atrial fibrillation and hypertrophic cardiomyopathy due to high risk of thromboembolism. The available observational data reviewed here suggests that direct oral anticoagulants may be safe and effective to be used in this patient population. However, adequately powered randomized controlled trials are needed to confirm their efficacy and safety.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 02 Oct 2020; epub ahead of print
Nasser MF, Gandhi S, Siegel RJ, Rader F
Heart Rhythm: 02 Oct 2020; epub ahead of print | PMID: 33022393
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Impact:
Abstract

Critical repolarization gradients determine the induction of reentry-based Torsade de Pointes arrhythmia in models of long QT syndrome.

Rivaud MR, Bayer JD, Cluitmans M, van der Waal J, ... Meijborg VMF, Coronel R
Background
Torsade de Pointes arrhythmia is a potentially lethal polymorphic ventricular tachyarrhythmia (pVT) in the setting of long QT syndrome. Arrhythmia susceptibility is influenced by risk factors modifying repolarization.
Objective
To characterize repolarization duration and heterogeneity in relation to pVT inducibility and maintenance.
Methods
Sotalol was infused regionally or globally in isolated Langendorff blood-perfused pig hearts (N=7) to create repolarization time (RT) heterogeneities. Programmed stimulation and epicardial activation and repolarization mapping were performed. The role of RT (heterogeneities) was studied in more detail using a computer model of the human heart.
Results
pVTs (n=11) were inducible at a critical combination of RT and RT heterogeneities. The pVT cycle lengths were similar in the short and long RT regions. Short-lasting pVTs were maintained by focal activity while longer-lasting pVTs by reentry wandering along the interface between the two regions. Local restitution curves from the long and short RT regions crossed. This was associated with T-wave inversion at coupling intervals at either side of the crossing-point. These experimental observations were confirmed by the computer simulations.
Conclusions
pVTs are inducible within a critical range of RT and RT heterogeneities and are maintained by reentry wandering along the repolarization gradient. Double potentials localize at the core of the reentrant circuit and reflect phase singularities. RT gradient and T-waves invert with short coupled premature beats in the long RT region as a result of the crossing of the restitution curves allowing reentry initiation.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 04 Oct 2020; epub ahead of print
Rivaud MR, Bayer JD, Cluitmans M, van der Waal J, ... Meijborg VMF, Coronel R
Heart Rhythm: 04 Oct 2020; epub ahead of print | PMID: 33031961
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Impact:
Abstract

Blood-based 8-hydroxy-2\'-deoxyguanosine level: a potential diagnostic biomarker for Atrial Fibrillation.

Li J, Zhang D, Ramos KS, Baks L, ... de Groot NMS, Brundel BJJM
Background
Recent research findings revealed key role for oxidative DNA damage in the pathogenesis of atrial fibrillation (AF). Therefore, a circulating oxidative DNA damage marker 8-hydroxy-2\'-deoxyguanosine (8-OHdG) may represent a biomarker to stage AF and identify patients at risk for AF recurrence and POAF after treatment.
Objectives
To investigate whether serum levels of 8-OHdG correlate with the stage of AF, recurrence after AF treatment and onset of post-operative AF (POAF) after cardiac surgery.
Methods
In this prospective and observational study, 8-OHdG levels are detected by ELISA in human serum samples. Blood samples were collected from control patients without AF history, paroxysmal AF and persistent AF patients undergoing electrical cardioversion (ECV) or pulmonary vein isolation (PVI), and sinus rhythm (SR) patients undergoing cardiac surgery. AF recurrence was determined during 12 months follow-up. Univariate and multivariate analysis were used to identify changes in 8-OHdG levels between the groups.
Results
Compared to the control group, 8-OHdG levels gradually and significantly increased during progression of this arrhythmia. Also 8-OHdG levels in AF patients showing an AF recurrence after PVI treatment were significantly increased compared to patients without AF recurrence. Moreover, in SR patients undergoing cardiac surgery, 8-OHdG levels were significantly elevated in patients showing POAF compared to patients without POAF.
Conclusions
The level of 8-OHdG may represent a potential diagnostic biomarker for AF staging, as well as prediction of AF recurrence and POAF after treatment.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 04 Oct 2020; epub ahead of print
Li J, Zhang D, Ramos KS, Baks L, ... de Groot NMS, Brundel BJJM
Heart Rhythm: 04 Oct 2020; epub ahead of print | PMID: 33031960
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Impact:
Abstract

Implant, Performance, and Retrieval of an Atrial Leadless Pacemaker in Sheep.

Vatterott PJ, Eggen MD, Hilpisch KE, Drake RA, ... Mesich ML, Ramon LC
Background
Medtronic is developing an atrial Micra™ Transcatheter Pacing System and associated retrieval system.
Objective
To evaluate chronic atrial Micra retrieval, re-implant, and chronic pacing performance.
Methods
Sheep were implanted in two groups. Group 1 (G1, n=6) for six months, a second device implanted and first retrieved and studied an additional six months. Group 2 (G2, n=6) for six months, devices were retrieved, and a second device implanted and observed acutely. Both groups underwent histopathologic evaluation. Pacing capture threshold (PCT), p-waves, and pacing impedances were measured chronically. Device retrieval times recorded and intracardiac echo was used.
Results
At 24 weeks, PCTs for G1 were low and stable for both the first device (0.55±0.14V) and second device (0.57±0.09V) where average retrieval time was 17:35 minutes (min). For G2, average retrieval time was 6:12 min, chronic PCTs in the first device were (0.53±0.11V), and acute PCTs for the second device were 0.71±0.19V. Pathologic findings were within an expected range of tissue responses for similar Micra acute and chronic implants and device retrievals. P-waves and impedance were stable and within an expected range for implant site and electrode design. Complications included one early dislodgement and one death attributed to a prototype retrieval tool.
Conclusions
In an animal model an atrial Micra can be easily implanted with excellent chronic pacing performance and is easily retrievable at six months. A second device can successfully be implanted with low, chronic stable thresholds. A developed prototype retrieval tool was easy to use and, with modifications, complication free.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 05 Oct 2020; epub ahead of print
Vatterott PJ, Eggen MD, Hilpisch KE, Drake RA, ... Mesich ML, Ramon LC
Heart Rhythm: 05 Oct 2020; epub ahead of print | PMID: 33035647
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Impact:
Abstract

Combined Epicardial and Endocardial Ablation for Atrial Fibrillation: Best Practices and Guide to Hybrid Convergent Procedures.

Makati KJ, Sood N, Lee LS, Yang F, ... Tondo C, Steinberg JS

The absence of strategies to consistently and effectively address non-paroxysmal atrial fibrillation (AF) by nonpharmacologic interventions has represented a longstanding treatment gap. A combined epicardial/endocardial ablation strategy, the hybrid Convergent procedure, was developed in response to this clinical need. A subxiphoid incision is used to access the pericardial space facilitating an epicardial ablation directed at isolation of the posterior wall of the left atrium. This is followed by an endocardial ablation to complete isolation of the pulmonary veins and for additional ablation as needed. Experience gained with the hybrid Convergent procedure during the last decade has led to the development and adoption of strategies to optimize the technique and mitigate risks. Additionally, a surgical and electrophysiology \"team\" approach including comprehensive training is believed critical to successfully develop the hybrid Convergent program. A recently completed randomized clinical trial indicated that this ablation strategy is superior to an endocardial only approach for patients with persistent AF. In this review, we propose and describe best practice guidelines for hybrid Convergent ablation based on a combination of published data, author consensus, and expert opinion. A summary of clinical outcomes, emerging evidence, and future perspectives are also discussed.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 08 Oct 2020; epub ahead of print
Makati KJ, Sood N, Lee LS, Yang F, ... Tondo C, Steinberg JS
Heart Rhythm: 08 Oct 2020; epub ahead of print | PMID: 33045430
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Impact:
Abstract

Pectoral nerve blocks decrease postoperative pain and opioid use after pacemaker or implantable cardioverter-defibrillator placement in children.

Yang JK, Char DS, Motonaga KS, Navaratnam M, ... Goodyer WR, Ceresnak SR
Background
Pectoral nerve blocks (PECs) can reduce intraprocedural anesthetic requirements and postoperative pain. Little is known about the utility of PECs in reducing pain and narcotic use after pacemaker (PM) or implantable cardioverter-defibrillator (ICD) placement in children.
Objective
The purpose of this study was to determine whether PECs can decrease postoperative pain and opioid use after PM or ICD placement in children.
Methods
A single-center retrospective review of pediatric patients undergoing transvenous PM or ICD placement between 2015 and 2020 was performed. Patients with recent cardiothoracic surgery or neurologic/developmental deficits were excluded. Demographics, procedural variables, postoperative pain, and postoperative opioid usage were compared between patients who had undergone PECs and those who had undergone conventional local anesthetic (Control).
Results
A total of 74 patients underwent PM or ICD placement; 20 patients (27%) underwent PECs. There were no differences between PECs and Control with regard to age, weight, gender, type of device placed, presence of congenital heart disease, type of anesthesia, procedural time, or complication rates. Patients who underwent PECs had lower pain scores at 1, 2, 6, 18, and 24 hours compared to Control. PECs patients had a lower mean cumulative pain score [PECs 1.5 (95% confidence interval [CI] 0.8-2.2) vs Control 3.1 (95% CI 2.7-3.5); P <.001] and lower total opioid use [PECs 6.0 morphine milligram equivalent (MME)/m (95% CI 3.4-8.6) vs Control 15.0 MME/m (95% CI 11.8-18.2); P = .001] over the 24 hours postimplant.
Conclusion
PECs reduce postoperative pain scores and lower total opioid usage after ICD or PM placement. PECs should be considered at the time of transvenous device placement in children.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1346-1353
Yang JK, Char DS, Motonaga KS, Navaratnam M, ... Goodyer WR, Ceresnak SR
Heart Rhythm: 30 Jul 2020; 17:1346-1353 | PMID: 32201270
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Impact:
Abstract

Acute and long-term results of bipolar radiofrequency catheter ablation of refractory ventricular arrhythmias of deep intramural origin.

Igarashi M, Nogami A, Fukamizu S, Sekiguchi Y, ... Aonuma K, Ieda M
Background
Successful bipolar radiofrequency catheter ablation (RFCA) of refractory ventricular arrhythmias (VAs) has been reported. However, the efficacy, safety, and long-term outcomes of bipolar RFCA of VAs are not fully determined.
Objective
The purpose of this study was to evaluate the effectiveness and safety of bipolar RFCA in treating refractory VAs during long-term follow-up.
Methods
Eighteen patients who underwent bipolar RFCA for ventricular tachycardia (VT) at 7 institutions were retrospectively investigated. Underlying heart diseases included remote myocardial infarction (n = 3 [17%]) and nonischemic cardiomyopathy (n = 15 [83%]). Although unipolar RFCA was performed in all patients, either it failed to suppress VT or VT recurred. The interventricular septum, left ventricular free wall, and left ventricular summit were targeted for bipolar RFCA.
Results
Acute success (VT termination and/or noninducibility) was achieved with bipolar RFCA in 16 patients (89%). Complications during the procedure included complete atrioventricular block (n = 2) and coronary artery stenosis (n = 1). One patient underwent chemical ablation after bipolar RFCA failure. At 12-month follow-up, VT reoccurred in 8 patients (44%). However, in patients with recurrence, VT burden had decreased: only 4 patients underwent re-RFCA, and only 1 of the 4 required chemical ablation. In the remaining 4 patients, re-RFCA was not required, as VT was controlled by medication or an implantable cardioverter-defibrillator.
Conclusion
Bipolar RFCA is useful for acute suppression of refractory VT. Although VT recurrence rates during long-term follow-up were relatively high, we observed a significant reduction in VT burden.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1500-1507
Igarashi M, Nogami A, Fukamizu S, Sekiguchi Y, ... Aonuma K, Ieda M
Heart Rhythm: 30 Aug 2020; 17:1500-1507 | PMID: 32353585
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Impact:
Abstract

Ostial dimensional changes after pulmonary vein isolation: Pulsed field ablation vs radiofrequency ablation.

Kuroki K, Whang W, Eggert C, Lam J, ... Neuzil P, Reddy VY
Background
Pulmonary vein (PV) stenosis is an important potential complication of PV isolation using thermal modalities such as radiofrequency ablation (RFA). Pulsed field ablation (PFA) is an alternative energy that causes nonthermal myocardial cell death.
Objective
The purpose of this study was to compare the effect of PFA vs RFA on the incidence and severity of PV narrowing or stenosis.
Methods
Data were analyzed from 4 paroxysmal atrial fibrillation ablation trials using either PFA or RFA; because of absent CT scans or poor computed tomography scan quality, 73 of 153 patients (47.7%) were excluded. Baseline and 3-month cardiac computed tomography scans were reconstructed into 3-dimensional images, and the long and short axes of the PV ostia were quantitatively and qualitatively assessed in a randomized blinded manner by 2 physicians.
Results
A total of 299 PVs from 80 patients after either PFA (n = 37) or RFA (n = 43) were enrolled. PV ostial diameters decreased significantly less with PFA than with RFA (% change; long axis: 0.9% ± 8.5% vs -11.9% ± 16.3%; P < .001 and short axis: 3.4% ± 12.7% vs -12.9% ± 18.5%; P < .001). After a combined quantitative/qualitative analysis, mild (30%-49%), moderate (50%-69%), or severe (70%-100%) PV narrowing was observed, respectively, in 9.0% (15 of 166), 1.8% (3 of 166), and 1.2% (2 of 166) of PVs in the RFA cohort but in none of the PVs after PFA (P < .001). Overall, PV narrowing/stenosis was present in 0% and 0% vs 12.0% and 32.5% of PVs and patients who underwent PFA and RFA, respectively.
Conclusion
This study indicates that unlike after RFA, the incidence and severity of PV narrowing/stenosis after PV isolation is virtually eliminated with PFA.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1528-1535
Kuroki K, Whang W, Eggert C, Lam J, ... Neuzil P, Reddy VY
Heart Rhythm: 30 Aug 2020; 17:1528-1535 | PMID: 32380290
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Impact:
Abstract

Optical capture and defibrillation in rats with monocrotaline-induced myocardial fibrosis 1 year after a single intravenous injection of adeno-associated virus channelrhodopsin-2.

Li J, Wang L, Luo J, Li H, ... Wang X, Huang C
Background
Optogenetics uses light to regulate cardiac rhythms and terminate malignant arrhythmias.
Objective
The purpose of this study was to investigate the long-term validity of optical capture properties based on virus-transfected channelrhodopsin-2 (ChR2) and evaluate the effects of optogenetic-based defibrillation in an in vivo rat model of myocardial fibrosis enhanced by monocrotaline (MCT).
Methods
Fifteen infant rats received jugular vein injection of adeno-associated virus (AAV). After 8 weeks, 5 rats were randomly selected to verify the effectiveness ChR2 transfection. The remaining rats were administered MCT at 11 months. Four weeks after MCT, the availability of 473-nm blue light to capture heart rhythm in these rats was verified again. Ventricular tachycardia (VT) and ventricular fibrillation (VF) were induced by burst stimulation on the basis of enhanced myocardial fibrosis, and the termination effects of the optical manipulation were tested.
Results
Eight weeks after AAV injection, there was ChR2 expression throughout the ventricular myocardium as reflected by both fluorescence imaging and optical pacing. Four weeks after MCT, significant myocardial fibrosis was achieved. Light could still trigger the corresponding ectopic heart rhythm, and the pulse width and illumination area could affect the light capture rate. VT/VF was induced successfully in 1-year-observation rats, and the rate of termination of VT/VF under light was much higher than that of spontaneous termination.
Conclusion
Viral ChR2 transfection can play a long-term role in the rat heart, and light can successfully regulate heart rhythm and defibrillate after cardiac fibrosis.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 07 Aug 2020; epub ahead of print
Li J, Wang L, Luo J, Li H, ... Wang X, Huang C
Heart Rhythm: 07 Aug 2020; epub ahead of print | PMID: 32781160
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Impact:
Abstract

Efficacy and safety of combined endocardial/epicardial catheter ablation for ventricular tachycardia in Chagas disease: A randomized controlled study.

Pisani CF, Romero J, Lara S, Hardy C, ... Di Biase L, Scanavacca M
Background
Epicardial mapping and ablation are frequently necessary to eliminate ventricular tachycardia (VT) in patients with Chagas disease. Nonetheless, there are no randomized controlled trials demonstrating the role of this strategy.
Objective
We conducted this randomized controlled trial to evaluate the efficacy and safety of combined epicardial ablation in patients with Chagas disease.
Methods
We randomized patients with Chagas disease and VT in a 1:1 fashion to either the endocardial (endo) mapping and ablation group or the combined endocardial/epicardial (endo/epi) mapping and ablation group. The efficacy end points were measured by VT inducibility and all-ventricular arrhythmia recurrence. Safety was assessed by the rate of periprocedural complications.
Results
Thirty patients were enrolled, and most were male. The median age was 67 (Q1: 58; Q3: 70) years in the endo group and 58 (Q1: 43; Q3: 66) years in the endo/epi group. The left ventricular ejection fraction was 33.0% ± 9.5% and 35.2% ± 11.5%, respectively P = .13. Acute success (non-reinducibility of clinical VT) was obtained in 13 patients (86%) in the endo/epi group and in 6 patients (40%) in the endo-only group (P = .021). There were 12 patients with VT recurrence (80%) in the endo-only group and 6 patients (40%) in the endo/epi group (P = .02) (by intention-to-treat analysis). Epicardial ablation was ultimately performed in 9 patients (60%) in the endo-only group because of an absence of endocardial scar or maintenance of VT inducibility. There was no difference in complications between the groups.
Conclusion
Combining endo/epi VT catheter ablation in patients with Chagas disease significantly increases short- and long-term freedom from all-ventricular arrhythmias. Epicardial access did not increase periprocedural complication rates.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1510-1518
Pisani CF, Romero J, Lara S, Hardy C, ... Di Biase L, Scanavacca M
Heart Rhythm: 30 Aug 2020; 17:1510-1518 | PMID: 32087356
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Impact:
Abstract

Stereotactic arrhythmia radioablation for refractory scar-related ventricular tachycardia.

Gianni C, Rivera D, Burkhardt JD, Pollard B, ... Natale A, Al-Ahmad A
Background
Recently, stereotactic radiosurgery has been applied to arrhythmias (stereotactic arrhythmia radioablation [STAR]), with promising results reported in patients with refractory scar-related ventricular tachycardia (VT), a cohort with known high morbidity and mortality.
Objective
Herein, we describe our experience with STAR, detailing its early and mid- to long-term results.
Methods
This is a pilot prospective study of patients undergoing STAR for refractory scar-related VT. The anatomical target for radioablation was defined on the basis of the clinical VT morphology, electroanatomic mapping, and study-specific preprocedural imaging with cardiac computed tomography. The target volume was treated with a prescription radiation dose of 25 Gy delivered in a single fraction by CyberKnife in an outpatient setting. Ventricular arrhythmias and radiation-related adverse events were monitored at follow-up to determine STAR efficacy and safety.
Results
Five patients (100% men; mean age 63 ± 12 years; 80% with ischemic cardiomyopathy; left ventricular ejection fraction 34% ± 15%) underwent STAR. Radioablation was delivered in 82 ± 11 minutes without acute complications. During a mean follow-up of 12 ± 2 months, all patients experienced clinically significant mid- to late-term ventricular arrhythmia recurrence; 2 patients died of complications associated with their advanced heart failure. There were no clinical or imaging evidence of radiation-induced complications in the organs at risk surrounding the scar targeted by radioablation.
Conclusion
Despite good initial results, STAR did not result in effective arrhythmia control in the long term in a selected high-risk population of patients with scar-related VT. The safety profile was confirmed to be favorable, with no radiation-related complications observed during follow-up. Further studies are needed to explain these disappointing results.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1241-1248
Gianni C, Rivera D, Burkhardt JD, Pollard B, ... Natale A, Al-Ahmad A
Heart Rhythm: 30 Jul 2020; 17:1241-1248 | PMID: 32151737
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Impact:
Abstract

Real-world experience of leadless left ventricular endocardial cardiac resynchronization therapy: A multicenter international registry of the WiSE-CRT pacing system.

Sieniewicz BJ, Betts TR, James S, Turley A, ... Behar J, Rinaldi CA
Background
Biventricular endocardial pacing (BiV ENDO) is a therapy for heart failure patients who cannot receive transvenous epicardial cardiac resynchronization therapy (CRT) or have not responded adequately to CRT. BiV ENDO CRT can be delivered by a new wireless LV ENDO pacing system (WiSE-CRT system; EBR Systems, Sunnyvale, CA), without the requirement for lifelong anticoagulation.
Objective
The purpose of this study was to assess the safety and efficacy of the WiSE-CRT system during real-world clinical use in an international registry.
Methods
Data were prospectively collected from 14 centers implanting the WiSE-CRT system as part of the WiCS-LV Post Market Surveillance Registry. (ClinicalTrials.gov Identifier: NCT02610673).
Results
Ninety patients from 14 European centers underwent implantation with the WiSE-CRT system. Patients were predominantly male, age 68.2 ± 10.5 years, left ventricular ejection fraction 30.6% ± 8.9%, mean QRS duration 180.7 ± 27.0 ms, and 40% with ischemic etiology. Successful implantation and delivery of BiV ENDO pacing was achieved in 94.4% of patients. Acute (<24 hours), 1- to 30-day, and 1- to 6-month complications rates were 4.4%, 18.8%, and 6.7%, respectively. Five deaths (5.6%) occurred within 6 months (3 procedure related). Seventy percent of patients had improvement in heart failure symptoms.
Conclusion
BiV ENDO pacing with the WiSE-CRT system seems to be technically feasible, with a high success rate. Three procedural deaths occurred during the study. Procedural complications mandate adequate operator training and implantation at centers with immediately available cardiothoracic and vascular surgical support.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1291-1297
Sieniewicz BJ, Betts TR, James S, Turley A, ... Behar J, Rinaldi CA
Heart Rhythm: 30 Jul 2020; 17:1291-1297 | PMID: 32165181
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Impact:
Abstract

Atrial tachycardia eliminated at the ventricular side in patients with congenitally corrected transposition of the great arteries: Electrophysiological findings and anatomical concerns.

Jiang CX, Long DY, Du X, Sang CH, ... Dong JZ, Ma CS
Background
The unique malformation of congenitally corrected transposition of the great arteries (cc-TGA) makes the pulmonary outflow tract (POT) a possible origin of atrial tachycardia (AT).
Objective
The purpose of this study was to investigate the mapping characteristics of ATs successfully ablated at the POT in patients with cc-TGA.
Methods
Patients with cc-TGA with AT eliminated at the POT were analyzed. Activation mapping of the atria and POT was performed under the guidance of a 3-dimensional electroanatomic mapping system. The activation pattern of these chambers was investigated, with the local activation time (LAT; using coronary sinus ostium as a reference) of the earliest activation site (EAS) being compared.
Results
AT eliminated at the POT was documented in 5 of 6 patients with cc-TGA. The EAS was at the right anteroseptal region with a LAT of 33 (21-120) ms in the right atrium and at the septal wall with a comparable LAT (26, 47, and 26 ms; P = .604) in the left atrium. The EAS of the POT was in the vicinity of the left-facing pulmonary sinus cusp in 3 cases and the nonfacing pulmonary sinus cusp in 2 cases, with a LAT of 106 (28-134) ms preceding both atria. Ablation at this site successfully eliminated AT in all 5 cases.
Conclusion
AT arising adjacent to the POT is not an uncommon tachycardia in patients with situs solitus-type cc-TGA and can be safely eliminated by ablation targeting the EAS in the POT.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1337-1345
Jiang CX, Long DY, Du X, Sang CH, ... Dong JZ, Ma CS
Heart Rhythm: 30 Jul 2020; 17:1337-1345 | PMID: 32201269
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Impact:
Abstract

Cardiac radioablation-A systematic review.

van der Ree MH, Blanck O, Limpens J, Lee CH, ... Robinson CG, Postema PG

Failure of drugs and catheter ablation procedures for the treatment of ventricular arrhythmias is still extremely relevant. Recently, stereotactic body radiotherapy has been introduced to treat therapy refractory patients. In this systematic review (International Prospective Register of Systematic Reviews, CRD42019133212), we aimed to summarize electrophysiological and histopathological effects of radioablation in animals, patients, and extracted and perfused hearts. A systematic search was performed in OVID MEDLINE, OVID Embase, the Cochrane Central Register of Controlled Trials, Web of Science, Google Scholar, ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) from inception to September 2019. Identified records were independently screened for eligibility by 2 reviewers. Risk of bias and methodological quality were assessed using the SYRCLE, ROBINS-I, or Murad tool and tailored to the different study designs. We included 13 preclinical and 10 clinical publications. Large heterogeneity in study designs prompted a narrative synthesis approach. Baseline, (pre-)procedural details, outcome, target tissue analyses, and safety data were extracted and summarized. In animal studies evaluating electrophysiological parameters, radioablation induced a reduction in voltage/potential amplitude or bidirectional block in target areas in 93.2% of animals. Atrioventricular block (first to third degree) was induced in 78.3% of animals, and in studies evaluating ventricular arrhythmia inducibility, 75% reduction was achieved. In patients, predominantly ventricular tachycardias were targeted with >85% reduction in arrhythmia episodes during follow-up with an encouraging short-term safety profile. Preclinical and clinical evidence on the efficacy and safety of radioablation is limited in both quantity and quality. The results of radioablation for therapy refractory patients with ventricular tachycardia are promising, but further research is needed.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1381-1392
van der Ree MH, Blanck O, Limpens J, Lee CH, ... Robinson CG, Postema PG
Heart Rhythm: 30 Jul 2020; 17:1381-1392 | PMID: 32205299
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Impact:
Abstract

Combined local impedance and contact force for radiofrequency ablation assessment.

Garrott K, Laughner J, Gutbrod S, Sugrue A, ... Meyers J, Kapa S
Background
The combination of contact force (CF) and local impedance (LI) may improve tissue characterization and lesion prediction during radiofrequency (RF) ablation.
Objective
The purpose of this study was to evaluate the utility of LI combined with CF in assessing RF ablation efficacy.
Methods
An LI catheter with CF sensing was evaluated in swine (n = 11) and in vitro (n = 14). The relationship between LI and CF in different tissue types was evaluated in vivo. Discrete lesions were created in vitro and in vivo at a range of forces, powers, and durations. Finally, an intercaval line was created in 3 groups at 30 W: 30s, Δ20Ω, and Δ30Ω. In the Δ20Ω and Δ30Ω groups, the user ablated until a 20 or 30 Ω LI drop. In the 30s group, the user was blinded to LI.
Results
In vivo, distinction in LI was found between the blood pool and the myocardium (blood pool: 122 ± 7.02 Ω; perpendicular contact: 220 ± 29 Ω; parallel contact: 207 ± 31 Ω). LI drop correlated with lesion depth both in vitro (R = 0.84) and in vivo (R = 0.79), informing sufficient lesion creation (LI drop >20 Ω) and warning of excessive heating (LI drop >65 Ω). When creating an intercaval line, the total RF time was significantly reduced when using LI guidance (6.4 ± 2 minutes in Δ20Ω and 8.1 ± 1 minutes in Δ30Ω) compared with a standard 30-second workflow (18 ± 7 minutes). Acute conduction block was achieved in all Δ30Ω and 30s lines.
Conclusion
The addition of LI to CF provides feedback on both electrical and mechanical loads. This provides information on tissue type and catheter-tissue coupling; provides feedback on whether volumetric tissue heating is inadequate, sufficient, or excessive; and reduces ablation time.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1371-1380
Garrott K, Laughner J, Gutbrod S, Sugrue A, ... Meyers J, Kapa S
Heart Rhythm: 30 Jul 2020; 17:1371-1380 | PMID: 32240822
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Impact:
Abstract

Leadless pacemakers reduce risk of device-related infection: Review of the potential mechanisms.

El-Chami MF, Bonner M, Holbrook R, Stromberg K, ... Sohail MR, Epstein LM

Pacemaker-related infections remain a constant concern due to increased risk of patient morbidity and mortality. Although transvenous pacemakers are expected to have an infection rate ranging from 0.77% to 2.08%, no cases of leadless pacemaker infection have been reported in clinical trials enrolling more than 3000 patients. Many potential reasons why leadless pacemakers may be resistant to infection include the absence of a subcutaneous pocket and leads, reduced skin and glove contact, size, location, and device material. This review summarizes the current state of evidence regarding the apparent infection resistance of leadless pacemakers.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1393-1397
El-Chami MF, Bonner M, Holbrook R, Stromberg K, ... Sohail MR, Epstein LM
Heart Rhythm: 30 Jul 2020; 17:1393-1397 | PMID: 32247833
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Impact:
Abstract

The various manifestations of concealed nodofascicular/nodoventricular bypass tracts.

Ho RT, Ortman M, Levi SA
Background
The various arrhythmic manifestations of concealed nodofascicular (NF)/nodoventricular (NV) bypass tracts (BPTs) are poorly understood.
Objective
The purpose of the study was to define diagnostic criteria for supraventricular tachycardias (SVTs) associated with concealed nodal pathways (NPs).
Methods
We reviewed 11 patients with concealed NPs who underwent electrophysiology study and ablation for symptomatic SVT.
Results
Of 11 patients 7 (64% women; mean age 54 ± 16 years), NF/NV BPTs were active bystanders during atrioventricular nodal reentrant tachycardia (atypical [n = 4]; typical [n =2]) or participants during orthodromic NF/NV reentrant tachycardia (n = 5). The majority (10 of 11 [91%]) had nodal origin in the slow pathway (SP) and 7 of 11 (64%) presented as long RP SVT. Ablation of the SP targeting the right (n = 10) or left (n = 1) inferior extension eliminated concealed NP-associated SVTs in all patients.
Conclusion
Concealed NF/NV BPTs are active bystanders equally as common as participants during SVT. They typically insert into the SP and often present as long RP SVT. SP ablation eliminates concealed NF/NV BPT-associated SVTs regardless of the mechanism.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1280-1290
Ho RT, Ortman M, Levi SA
Heart Rhythm: 30 Jul 2020; 17:1280-1290 | PMID: 32268209
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Impact:
Abstract

Linking cellular energy state to atrial fibrillation pathogenesis: Potential role of adenosine monophosphate-activated protein kinase.

Chakraborty P, Nattel S, Nanthakumar K

Adenosine monophosphate-activated protein kinase (AMPK) is the cellular stress-sensing molecule. Apart from maintaining cellular energy balance, AMPK controls expression and regulation of ion channels and ion transporters, including cytosolic Ca handling proteins. Emerging evidence suggests that metabolic impairment plays a crucial role in the pathogenesis of atrial fibrillation. AMPK activation is thought to be protective by preventing metabolic stress, favorably modulating membrane electrophysiology including cytosolic Ca dynamics; preventing cellular growth; and hypertrophic remodeling. This review considers current concepts and evidence from clinical and experimental studies regarding the role of AMPK in atrial fibrillation.

Copyright © 2020 Heart Rhythm Society. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1398-1404
Chakraborty P, Nattel S, Nanthakumar K
Heart Rhythm: 30 Jul 2020; 17:1398-1404 | PMID: 32268208
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Impact:
Abstract

Prophylactic (hydroxy)chloroquine in COVID-19: Potential relevance for cardiac arrhythmia risk.

Offerhaus JA, Wilde AAM, Remme CA

(Hydroxy)chloroquine ((H)CQ) is being investigated as a treatment for COVID-19, but studies have so far demonstrated either no or a small benefit. However, these studies have been mostly performed in patients admitted to the hospital and hence likely already (severely) affected. Another suggested approach uses prophylactic (H)CQ treatment aimed at preventing either severe acute respiratory syndrome coronavirus 2 infection or the development of disease. A substantial number of clinical trials are planned or underway aimed at assessing the prophylactic benefit of (H)CQ. However, (H)CQ may lead to QT prolongation and potentially induce life-threatening arrhythmias. This may be of particular relevance to patients with preexisting cardiovascular disease and those taking other QT-prolonging drugs. In addition, it is known that a certain percentage of the population carries genetic variant(s) that reduces their repolarization reserve, predisposing them to (H)CQ-induced QT prolongation, and this may be more relevant to female patients who already have a longer QT interval to start with. This review provides an overview of the current evidence on (H)CQ therapy in patients with COVID-19 and discusses different strategies for prophylactic (H)CQ therapy (ie, preinfection, postexposure, and postinfection). In particular, the potential cardiac effects, including QT prolongation and arrhythmias, will be addressed. Based on these insights, recommendations will be presented as to which preventive measures should be taken when giving (H)CQ prophylactically, including electrocardiographic monitoring.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1480-1486
Offerhaus JA, Wilde AAM, Remme CA
Heart Rhythm: 30 Aug 2020; 17:1480-1486 | PMID: 32622993
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Impact:
Abstract

Cybersecurity: the need for data and patient safety with cardiac implantable electronic devices.

Das S, Siroky GP, Lee S, Mehta D, Suri R

Remote monitoring (RM) of Cardiac Implantable Electronic devices (CIEDs) has become routine practice owing to the advances in biomedical engineering, the advent of interconnectivity between the devices through the internet, and the demonstrated improvement in patient outcomes, survival, and hospitalizations. However, this increased dependency on the Internet of Things (IoT) comes with its risks in the form of cybersecurity lapses and possible attacks. While there has not been a cyberattack leading to patient harm reported in literature to date, the threat is real and has been demonstrated in research laboratory scenarios and echoed in patient concerns. The CIED universe comprises a complex interplay of devices, connectivity protocols, and sensitive information flow between the devices and the central cloud server. Various manufacturers use proprietary software and black-boxed connectivity protocols which are susceptible to hacking. In this paper, we discuss the fundamentals of the CIED ecosystem, the potential security vulnerabilities, a historical overview of such vulnerabilities reported in literature, and recommendations regarding improving the security of the CIED ecosystem and patient safety.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 11 Oct 2020; epub ahead of print
Das S, Siroky GP, Lee S, Mehta D, Suri R
Heart Rhythm: 11 Oct 2020; epub ahead of print | PMID: 33059076
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Impact:
Abstract

Left ventricular endocardial pacing is less arrhythmogenic than conventional epicardial pacing when pacing in proximity to scar.

Mendonca Costa C, Neic A, Gillette K, Porter B, ... Bishop MJ, Niederer SA
Background
Epicardial pacing increases risk of ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) when pacing in proximity to scar. Endocardial pacing may be less arrhythmogenic as it preserves the physiological sequences of activation and repolarization.
Objective
The purpose of this study was to determine the relative arrhythmogenic risk of endocardial compared to epicardial pacing, and the role of the transmural gradient of action potential duration (APD) and pacing location relative to scar on arrhythmogenic risk during endocardial pacing.
Methods
Computational models of ICM patients (n = 24) were used to simulate left ventricular (LV) epicardial and endocardial pacing 0.2-3.5 cm from a scar. Mechanisms were investigated in idealized models of the ventricular wall and scar. Simulations were run with/without a 20-ms transmural APD gradient in the physiological direction and with the gradient inverted. Dispersion of repolarization was computed as a surrogate of VT risk.
Results
Patient-specific models with a physiological APD gradient predict that endocardial pacing decreases VT risk (34%; P <.05) compared to epicardial pacing when pacing in proximity to scar (0.2 cm). Endocardial pacing location does not significantly affect VT risk, but epicardial pacing at 0.2 cm compared to 3.5 cm from scar increases it (P <.05). Inverting the transmural APD gradient reverses this trend. Idealized models predict that propagation in the direction opposite to APD gradient decreases VT risk.
Conclusion
Endocardial pacing is less arrhythmogenic than epicardial pacing when pacing proximal to scar and is less susceptible to pacing location relative to scar. The physiological repolarization sequence during endocardial pacing mechanistically explains reduced VT risk compared to epicardial pacing.

Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1262-1270
Mendonca Costa C, Neic A, Gillette K, Porter B, ... Bishop MJ, Niederer SA
Heart Rhythm: 30 Jul 2020; 17:1262-1270 | PMID: 32272230
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Impact:
Abstract

High-power, short-duration atrial fibrillation ablations using contact force sensing catheters: Outcomes and predictors of success including posterior wall isolation.

Winkle RA, Mead RH, Engel G, Kong MH, ... Brodt CR, Patrawala RA
Background
Little is known about the long-term outcomes and predictors of success of high-power, short-duration (HPSD) contact force (CF) atrial fibrillation (AF) ablations.
Objective
The purpose of this study was to determine long-term freedom from AF and predictors of freedom from AF for 50-W, 5- to 15-second CF ablation.
Methods
We examined 4-year outcomes and predictors of freedom from AF after AF ablation for 1250 consecutive patients undergoing HPSD CF ablations.
Results
Patient demographics were age 66.6 ± 10.5 years, female 30.9%, left atrial (LA) size 4.26 ± 0.66 cm, paroxysmal AF 35.7%, persistent AF 56.6%, and longstanding AF 7.7%. Initial ablation times were procedure 114.2 ± 45.9 minutes, fluoroscopy 15.5 ± 11.5 minutes, and total radiofrequency 20.6 ± 7.7 minutes. TactiCath was used in 47.7%, SmartTouch in 52.3%, and posterior wall isolation (PWI) was performed in 34%. Four-year freedom from AF after multiple ablations were paroxysmal AF 87.0%, persistent AF 71.9%, and longstanding AF 64.9%. Single procedure success was 74.9% for TactiCath, 64.7% for SmartTouch (P <.001), and 73.0% for no PWI vs 58.9% for PWI (P <.0001). PWI did not change outcomes for paroxysmal AF but had worse outcomes for nonparoxysmal AF. Multivariate analysis showed 6 independent predictors of worse outcome after initial ablation: older age (P = .014), female gender (P <.0001), persistent AF (P = .0001), larger LA size (P <.001), PWI (P = .049), and use of SmartTouch vs TactiCath catheter (P = .007). Redo ablations were performed in 13.8%, and the outcome was better when more veins had reconnected after the initial ablation and when AF was paroxysmal.
Conclusion
Analysis revealed 6 independent predictors of outcome for HPSD CF. At redo ablations, the outcome was better if more veins had reconnected and could be re-isolated.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Jul 2020; 17:1223-1231
Winkle RA, Mead RH, Engel G, Kong MH, ... Brodt CR, Patrawala RA
Heart Rhythm: 30 Jul 2020; 17:1223-1231 | PMID: 32272229
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Impact:
Abstract

Repeated exposure to transient obstructive sleep apnea related conditions causes an atrial fibrillation substrate in a chronic rat model.

Linz B, Hohl M, Lang L, Wong DWL, ... Böhm M, Linz D
Background
High night-to-night variability of obstructive sleep apnea (OSA) is associated with atrial fibrillation (AF). Obstructive apneas are characterized by intermittent deoxygenation-reoxygenation and intrathoracic pressure swings during ineffective inspiration against occluded upper airways.
Objective
We elucidated the effect of repeated exposure to transient OSA-conditions simulated by intermittent negative upper airway pressure (INAP) on the development of an AF-substrate.
Methods
INAP (48 events/4h, Apnea-Hypopnea-Index (AHI)=12/h) was applied in sedated spontaneously breathing rats (2% isoflurane) to simulate mild-to-moderate OSA. Rats without INAP served as controls (CTR). In an acute-test-series (ATS), rats were either sacrificed immediately (n=9/group) or after 24h of recovery (ATS-REC n=5/group). To simulate high night-to-night variability in OSA, INAP-applications (n=10; 24 events/4h, AHI=6/h) were repeated every second day for three weeks in a chronic-test-series (CTS).
Results
INAP increased atrial oxidative stress acutely, represented in decreases of reduced (GSH) to oxidized (GSSG) glutathione-ratio (ATS: INAP 0.33±0.05 vs. CTR 1±0.26; p=0.016), which was reversible after 24h (ATS-REC: INAP vs. CTR; p=n.s.). Although atrial oxidative stress did not accumulate in the CTS, atrial histological analysis revealed increased cardiomyocyte diameters, reduced connexin43 expression and increased interstitial fibrosis formation (CTS: INAP 7.0±0.5% vs. CTR 5.1±0.3%; p=0.013), which were associated with longer inducible AF-episodes (CTS: INAP 11.65±4.43 seconds vs. CTR 0.7±0.33 seconds; p=0.033).
Conclusions
Acute simulation of OSA was associated with reversible atrial oxidative stress. Cumulative exposure to these transient OSA-related conditions resulted in AF-substrates and was associated with increased AF-susceptibility. Mild-to-moderate OSA with high night-to-night variability may deserve intensive management to prevent atrial substrate development.

Copyright © 2020. Published by Elsevier Inc.

Heart Rhythm: 16 Oct 2020; epub ahead of print
Linz B, Hohl M, Lang L, Wong DWL, ... Böhm M, Linz D
Heart Rhythm: 16 Oct 2020; epub ahead of print | PMID: 33080392
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Impact:
Abstract

Subcutaneous implantable cardioverter-defibrillator troubleshooting in patients with a left ventricular assist device: A case series and systematic review.

Black-Maier E, Lewis RK, Barnett AS, Pokorney SD, ... Daubert JP, Piccini JP
Background
There are limited data on the performance of the subcutaneous implantable cardioverter-defibrillator (S-ICD) in patients with a left ventricular assist device (LVAD).
Objective
The purpose of this study was to describe the clinical course and outcomes of patients with both an S-ICD and an LVAD at our institution and via a systematic review of published studies.
Methods
We performed a retrospective cohort study of all patients who underwent LVAD implantation from 2009 to 2019 at Duke University Hospital. We also performed a systematic review of studies involving patients with an S-ICD and LVAD using the PubMed/Embase databases.
Results
Of 588 patients undergoing LVAD implantation with a preexisting implantable cardioverter-defibrillator, 4 had an S-ICD in situ after LVAD implantation. All 4 patients developed electromagnetic interference (EMI) in the primary/secondary vectors after LVAD implantation, resulting in inappropriate implantable cardioverter-defibrillator shocks in 2 patients. Sensing in the alternate vector was adequate immediately postoperatively in 1 patient. Postoperative undersensing was present in the alternate vector in 3 patients but improved at first outpatient follow-up in 2 patients, allowing tachy therapies to be reenabled. Eight studies involving 27 patients were identified in the systematic review. EMI was common and frequently absent in the alternate vector (6 of 7 patients).
Conclusion
Undersensing and EMI are common after LVAD implantation in patients with an S-ICD in situ, particularly in the primary and secondary sensing vectors. Undersensing in the alternate vector may improve during follow-up, obviating the need for device revision or extraction.

Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Heart Rhythm: 30 Aug 2020; 17:1536-1544
Black-Maier E, Lewis RK, Barnett AS, Pokorney SD, ... Daubert JP, Piccini JP
Heart Rhythm: 30 Aug 2020; 17:1536-1544 | PMID: 32304733
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Impact:
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