Elsevier

Heart Rhythm

Volume 19, Issue 12, December 2022, Pages 2075-2083
Heart Rhythm

Ventricular Tachycardia
Significance of abnormal and late ventricular signals in ventricular tachycardia ablation of ischemic and nonischemic cardiomyopathies

https://doi.org/10.1016/j.hrthm.2022.08.008Get rights and content

Background

Abnormal ventricular signals (AVS) are the cornerstone of substrate-based ventricular tachycardia (VT) ablation in sinus rhythm. Signal characterization of AVS in ischemic and nonischemic cardiomyopathies has never been performed.

Objective

The purpose of this study was to describe ventricular signal abnormalities in 3 different pathologies and examine their association with the diastolic component of VT circuits.

Methods

A total of 45 patients (15 ischemic cardiomyopathy [ICM], 15 arrhythmogenic cardiomyopathy [ACM], 15 dilated cardiomyopathy [DCM]) who had undergone VT ablation with >50% of the diastolic pathway of the VT circuit recorded were studied. AVS were classified into late potentials (LPs) and continuous fractionated ventricular signals (CFVS), and their characteristics and correlation with the diastolic pathway of VT circuits were analyzed.

Results

Seventy-five VT circuits were analyzed. Bipolar scars were greatest in ICM endocardially (53 cm2 ICM vs 36 cm2 ACM vs 25 cm2 DCM; P = .010) and in ACM epicardially (98 cm2 ACM vs 25 cm2 ICM vs 24 cm2 DCM; P = .005). Location of the VT diastolic interval coincided with AVS location in 54% of VTs in ICM, 89% in ACM, and 72% in DCM (P = .036). There was a trend toward a greater association of diastolic intervals coinciding with LPs than with CFVS (78% vs 57%; P = .052) (69% diastolic intervals in ICM coincided with LPs, 33% with CFVS; P = .063). All patients (100%) with CFVS in ACM had VT diastolic components arising from CFVS (33% ICM, 64% DCM; P = .049). Positive predictive value for LPs vs CFVS was 77.8% vs 56.7%, and sensitivity was 67.3% vs 32.7%, respectively.

Conclusion

The nature of abnormal signals in different cardiomyopathies reflects underlying pathology. LPs rather than CFVS seem to be more linked to diastolic components of VT circuits, especially in ICM. LPs have greater sensitivity and specificity for VT; however, CFVS may be of more relevance in ACM.

Introduction

Abnormal ventricular signals (AVS) characterize the pathologic substrate in the setting of ventricular arrhythmia treatment. Their relevance in ventricular tachycardia (VT) radiofrequency (RF) ablation has been the cornerstone of substrate-based ablation performed in sinus rhythm. Identification of the diastolic pathway has been proven to be superior to standard substrate ablation.1 However, this may be challenging due to hemodynamic instability associated with the clinical VT or noninducibility of the clinical tachycardia. Therefore, over the past few years, surrogates for critical components of the VT circuit have been sought, and the terms late potentials (LPs) and local abnormal ventricular activation (LAVA) have been very much in vogue. Definitions of abnormal signals that would include all of these have encompassed everything from fractionation within the QRS to split signals post-QRS. LP elimination has been associated with a reduction in the risk of VT recurrence, especially in patients with ischemic heart disease.2,3 It also has been demonstrated in nonischemic patients.4 LAVA elimination has been associated with good outcomes, mainly in ischemic cardiomyopathy patients.5,6

With the advent of multipolar mapping catheters that provide orthogonal vector information, ventricular electrograms (EGMs) are visualized in much greater detail today, and VT ablation outcomes have improved.7,8 Nevertheless, not all abnormal signals are capable of participating in a VT circuit. A formal investigation of AVS among the different pathologies has never been performed. The aim of the study was to characterize during sinus rhythm the prevalence of signal abnormalities in 3 cardiomyopathy etiologies (ischemic cardiomyopathy [ICM], arrhythmogenic cardiomyopathy [ACM], idiopathic dilated cardiomyopathy [DCM]) and to study their relevance in the diastolic component of a VT circuit.

Section snippets

Study population

A retrospective analysis was performed of 45 consecutive patients with both ischemic cardiomyopathy and nonischemic cardiomyopathy referred to San Raffaele Hospital, Department of Arrhythmology, for ablation of VT from February 2018 to June 2021. Each patient had undergone ablation with the EnSite Precision™ Cardiac Mapping System (Abbott, Minneapolis, MN), guided by high-density mapping with the Grid mapping catheter (Advisor HD Grid Mapping Catheter Sensor Enabled™, Abbott). The study was

Patient population

Forty-five patients were included in the study (15 ICM, 15 ACM, 15 DCM). Seventy-five VT circuits were included (median 1.7 VT circuits per patient). Mean age of the population was 56 ± 17 years. ACM patients were significantly younger and had better New York Heart Association functional class (Table 1). LV ejection fraction was significantly different between the groups (33% ± 8% ICM vs 56% ± 9% ACM vs 38% ± 15% DCM; P <.001). All ACM patients had previously undergone cardiac magnetic

Discussion

The aim of this study was to characterize the abnormal electrical ventricular substrate during sinus rhythm in patients with 3 different cardiomyopathies undergoing VT ablation. The main findings were as follows. (1) In our study population, LPs had higher sensitivity and specificity than CFVS, and it would appear that if an LP is detected, the probability is higher that the area identified by LPs falls into the diastolic interval. (2) CFVS seem to be of greater relevance in ACM, and the

Conclusion

The ventricular electrical substrate differs among cardiomyopathies. The EGM signature reflects the underlying architecture of the disease. LPs seem to correspond more to the critical area of the VT circuit, especially in ICM, whereas CFVS may be of more relevance in ACM. This is reflective of the nature of the underlying pathology, with discrete conduction channels in ICM and patchy nonuniform conduction and multiple channels in ACM. VT ablation in ACM requires an epicardial-first approach.

References (15)

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Funding Sources: The authors have no funding sources to disclose.

Disclosures: Drs Della Bella, Frontera, and Bisceglia received consultant fees from Abbott, Biosense Webster, and Boston Scientific. Dr Nakajima received grants from Biotronik. These disclosures are for pre-exisiting relationships the authors have had with industry. All other authors have no conflicts of interest to disclose.

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