Cardiac Resynchronization Therapy Reduces Ventricular Arrhythmias in Primary but Not Secondary Prophylactic Implantable Cardioverter Defibrillator Patients

Cardiac resynchronization defibrillators have been demonstrated to reduce both mortality and heart failure in patients with significant ventricular dysfunction and widened QRS. The influence of cardiac resynchronization therapy (CRT) on ventricular arrhythmias, however, is less certain. A systematic review of randomized controlled trials of more advanced heart failure populations with New York Heart Association class III-IV raised the concern that CRT may increase arrhythmia deaths, yet the CARE-HF trial (the Effect of Cardiac Resynchronization on Morbidity and Mortality in Heart Failure) demonstrated a reduction in mortality, including a reduction in sudden death in patients treated with CRT pacemakers. Small series and case studies have reported potential proarrhythmia related to biventricular pacing, and mechanistic and clinical studies have proposed potential mechanisms for a proarrhythmic effect of CRT. Nonetheless, both MADIT-CRT (the Cardiac-Resynchronization Therapy for the Prevention of Heart-Failure Events trial) and REVERSE