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 a mean follow-up of 2.5 years, 964 VTA episodes occurred in 264 patients (21%). The VTA rate per 100 personyears was significantly lower in the CRT-D group compared with the implantable cardioverter-defibrillator (ICD) group (20 vs 34; P <.01). Multivariate analysis demonstrated that CRT-D treatment was associated with a 32% risk reduction for VTA recurrence (hazard ratio 0.68; 95% confidence interval 0.57-0.82; P <.001), 57% risk reduction for recurrent life-threatening VTA, 54% risk reduction for recurrent appropriate ICD shocks, and 25% risk reduction for the combined endpoint of VTA and death. The effect of CRT-D on VTA burden was consistent among all tested subgroups but was more pronounced among patients in New York Heart Association functional class I. 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.

Automated summary

The study demonstrates that early intervention with CRT-D reduces the risk of VTA recurrence in patients with LBBB, and the effect of CRT-D on VTA burden is consistent among all tested subgroups.