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

Background: Cardiac resynchronization therapy (CRT) has significant benefits in selected patients (P). The impact of this modality in the incidence of ventricular tachyarrhythmias remains controversial. We analysed the occurrence of appropriate therapies in P submitted to CRT combined with a cardioverter-defibrillator (ICD).
Methods: Study of 123 P with left ventricular ejection fraction (LVEF) < 35%, submitted to successful implantation of CRT-ICD or ICD alone (primary prevention).
Results: Mean age was 63 +/- 12 years, LVEF of 25 +/- 6%, median follow-up of 372 days. CRT-ICD implanted in 63P (group A) and ICD alone in 60P (group B). Group A has 86% of clinical responders, lower prevalence of ischemic cardiomyopathy (30% vs. 72%), and more P in class III of the NYHA before device implantation (90% vs. 7%) compared with ICD alone patients. There were no differences in the incidence of appropriate therapies (19% vs. 12%) or in the time for first therapy (305 days vs. 293 days). Total 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 3.02, 95% CI 0.82 - 11.09, p = NS) when compared to patients without CRT.
Conclusions: In P submitted to CRT-ICD for primary prevention, despite a higher rate of responders, the incidence of appropriate therapies is not different from those with an ICD alone.