Incidence of ventricular arrhythmias in patients with severe left ventricular systolic dysfunction: is there a benefit after cardiac resynchronization therapy?

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IntroductionCardiac resynchronization therapy (CRT) has significant benefits in selected patients, but its impact on the incidence of ventricular tachyarrhythmias remains the subject of debate. We analyzed the occurrence of appropriate therapies in patients undergoing CRT combined with an implantable cardioverter-defibrillator (ICD). MethodsWe studied 123 patients with left ventricular ejection fraction (LVEF) <35%, who underwent successful implantation of CRT-ICD or ICD alone (primary prevention). ResultsMean age was 63±12 years, LVEF 25±6%, and median follow-up 372 days. CRT-ICD devices were implanted in 63 patients (group A) and ICD alone in 60 (group B). In Group A 86% were clinical responders, with a lower prevalence of ischemic cardiomyopathy (30% vs. 72%), and more patients in NYHA class III before device implantation (90% vs. 7%) compared to those with ICD alone. There were no differences in the incidence of appropriate therapies (19% vs. 12%) or in the time to first therapy (305 days vs. 293 days). Overall mortality was 11% in group A and 12% in group B. Kaplan-Meier curves for arrhythmic events in patients with CRT showed no significant differences (HR 1.71, 95% CI 0.67-4.36, p=NS) compared to those without CRT. ConclusionsDespite a higher rate of responders in patients with CRT-ICD for primary prevention, the incidence of appropriate therapies was similar to those with an ICD alone.