Cardiac Resynchronization Therapy and Ventricular Tachyarrhythmia Burden.

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 The purpose of this study was to assess the effect of CRT-D on VTA burden in LBBB patients. Methods We included 1281 patients with LBBB from MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial–Cardiac Resynchronization Therapy). 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 mean follow-up of 2.5 years, 964 VTA episodes occurred in 264 patients (21%). The VTA rate per 100 person-years was significantly lower in the CRT-D group compared with the implantable cardioverter-defibrillator (ICD) group (20 vs 34; P  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.