Is CRT pro-arrhythmic? A comparative analysis of the occurrence of ventricular arrhythmias between patients implanted with CRTs and ICDs

Abstract

Aim and Hypothesis: Despite the proven symptomatic and mortality benefit of cardiac resynchronisation therapy (CRT), there is anecdotal evidence it may be pro-arrhythmic in some patients. We aimed to identify if there were significant differences in the incidence of ventricular arrhythmias in patients undergoing CRT-D and ICD implantation for primary prevention indication. We hypothesised that CRT is unlikely to be pro-arrhythmic based on the positive mortality and morbidity data from large randomized trials. Methods and Results: A retrospective analysis of device therapies for ventricular arrhythmia (VA) in a primary prevention device cohort was performed. Patients with ischemic (IHD) and non-ischemic (DCM) cardiomyopathy and implantable cardioverter-defibrillators (ICD) or CRT+ICD devices (CRT-D) implanted between 2005 and 2007 without prior history of sustained ventricular arrhythmia were included for analysis. VA episodes were identified from stored electrograms and defined as sustained (VT/VF) if therapy (anti-tachycardia pacing (ATP) or shocks) was delivered or non-sustained (NSVT) if not. Of a total of 180 patients, 117 (68% male) were in the CRT-D group, 42% IHD, ejection fraction (EF) 24.5±8.2% and mean follow-up 23.9± 9.8 months. 63 patients (84% male) were in the ICD group, 60% IHD, EF 27.7±7.2% and mean follow-up 24.6±10.8 months. Overall, there was no significant difference in the incidence of ventricular arrhythmia (35.0% vs. 38.1%, p = 0.74), sustained VT (21.3% vs. 28.5%, p=0.36) or NSVT (12.8% vs. 9.5%, p=0.63) and no significant difference in type of therapy received for VT/VF: ATP (68% vs. 66.6%, p=0.73) and shocks (32% vs. 33.3%, p=0.71) between the CRT-D and ICD groups, respectively. Conclusion: In patients with cardiomyopathy receiving CRT-D and ICDs for primary prophylaxis, there was no significant difference in the incidence of ventricular arrhythmia. From this single centre retrospective analysis, there is no evidence to support cardiac resynchronisation causing pro-arrhythmia. © 2014 Gopalamurugan, Ganesha_babu, Rogers, Simpson, Ahsan, Lambiase, Chow, Lowe, Rowland and Segal.