Abstract
Purpose: Recent data suggest that real benefit of cardiac resynchronization therapy with a defibrillator (CRT-D) is circumscribed to patients (pts) with QRS duration greater than 150 milliseconds (ms). However there are few evidence as to whether this applies in the subset of pts with left bundle branch block (LBBB). The aim of our study was to assess the long-term effectiveness of CRT-D in real life pts with LBBB according to QRS duration.
Methods: we retrospectively studied 303 pts (age 66.0 ± 9.5 years, 75.2% male) included in the UMBRELLA Care Link National Registry who underwent a first implant of CRT-D between March 2007 to October 2014. They all have LBBB, LVEF ≤ 35%, and NYHA functional class II, III or IV ambulatory. We divided the pts into two groups according to QRS duration: 120-149 ms (group 1; n = 72) and ≥ 150 ms ( group 2; n = 231). The baseline characteristics of the sample and the frequency of events were studied. We performed the survival analysis with the Kaplan-Meier method and we conducted a multivariate Cox regression model to predict the probability of death or sustained ventricular arrhythmias.
Results: Mean follow-up was 900 ± 596 days. In most cases (91.4%) CRT-D was indicated for primary prevention of sudden death, 39.3% pts had ischemic heart disease and only 2.6% were in functional class IV ambulatory. The two groups were similar in baseline characteristics except for a greater presence of hypertension in the group 1 (76.4% vs 61.5%, p 0.020). No significant differences in mortality (11.1% vs 10.8%, p 0.945), sustained ventricular arrhythmias (16.7% vs 19.9%, p 0.541), electrical storm episodes or OptiVol® alerts were observed between groups 1 and 2, respectively. In multivariate analysis, no variable was an independent predictor of death or ventricular arrhythmias.
Conflict of interest: none
