ABSTRACT

BACKGROUND - Cardiac resynchronization therapy-defibrillator (CRT-D) may reduce the incidence of first ventricular tachyarrhythmia (VTA) in patients with heart failure (HF) and left bundle-branch-block (LBBB).

OBJECTIVE - To assess the effect of CRT-D on VTA burden in LBBB patients.

METHODS - We included 1281 patients with LBBB from MADIT-CRT. VTA was defined as any treated or monitored sustained ventricular tachycardia (VT≥180 bpm) or ventricular fibrillation (VF). Life-threatening VTA was defined as VT≥200 bpm or VF. VTA recurrence was assessed using the Andersen-Gill model.

RESULTS - During a mean follow-up of 2.5 years, 964 VTA episodes occurred in 264 (21%) patients. The VTA rate per 100 person-years was significantly lower in the CRT-D group when compared with the ICD group (20 vs. 34; respectively; p<0.01). Multivariate analysis demonstrated that CRT-D treatment was associated with a 32% risk reduction for VTA recurrence (HR=0.68; 95%CI 0.57-0.82; p<0.001), 57% risk reduction for recurrent life-threatening VTA, 54% risk reduction for recurrent appropriate ICD-shocks, and a 25% risk reduction for the combined endpoint of VTA and death. The effect of CRT on VTA burden was consistent among all tested subgroups, but was more pronounced among NYHA class I patients. Landmark analysis showed that at 2 years, the cumulative probability of death subsequent to year one was highest (16%) among patients who had ≥2 VTA events during their first year.

CONCLUSION - In patients with LBBB and HF, early intervention with CRT-D reduces mortality, VTA burden, and frequency of multiple appropriate ICD shocks. VTA burden is a powerful predictor of subsequent mortality.