Ventricular TachycardiaSignificance of abnormal and late ventricular signals in ventricular tachycardia ablation of ischemic and nonischemic cardiomyopathies
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.
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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.
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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.