Clinical Outcomes of Single vs. Dual Chamber Implantable Cardioverter Defibrillators: Lessons from the Israeli ICD Registry  

Introduction: Dual-chamber implantable cardioverter defibrillator (ICD) provides theoretical advantage over single-chamber ICD by improving supraventricular tachycardia discrimination, but the clinical superiority of dual-chamber ICD has not been conclusively proven. The aim of the present study was to compare the clinical outcomes of single versus dual chamber ICD for primary prevention population in a large, prospective national ICD registry.
Methods: Data were collected from the Israeli ICD registry. Baseline characteristics and clinical outcomes including appropriate and inappropriate ICD therapy, admissions for heart failure (HF), and mortality were compared between the two groups.
Results: Subjects implanted with a single or dual chamber ICD for primary prevention in Israel between July 2010 and September 2014 and had no indication for pacing or history of atrial fibrillation, were included. A total of 1125 subjects, of whom 418 (37%) were implanted with a single-chamber ICD constructed the baseline cohort. Approximately 80% of the patients in each group suffered from ischemic heart disease whereas ~18% had non ischemic cardiomyopathy. Mean follow-up was 22 months, mean ejection fraction was ~ 30% and mean QRS width was 103 ms in both groups. During follow-up, there were no significant differences in the rate of appropriate or inappropriate therapy, admissions for HF or death or in time to any of the clinical outcome according to Kaplan Meier curves. Using multivariate analysis single-chamber ICD was not associated with increased risk of inappropriate therapy, admission for HF, or death.
Conclusions: In this large population-based cohort dual-chamber ICD for primary prevention indication showed no benefit in reducing the incidence of inappropriate therapy, HF admissions or death compared to a single-chamber ICD.