Methods:

This study evaluated 734 patients of 1,820 patient group in the MADIT-CRT trial (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy). All had received CRT with a defibrillator (CRT-D). At time of enrollment in the MADIT-CRT trial, all patients had left ventricular ejection fraction (LVEF) <30%, QRS duration >130 ms, and New York Heart Association (NYHA) Class I or II ischemic or NYHA Class II nonischemic cardiomyopathy. NYHA functional class evaluation was available for all participants. Echocardiogram was obtained before device implantation and at 12 months of follow-up. Device interrogation was performed every 3 months. Those with ischemic cardiomyopathy, defined as improved beyond American Heart Association, American College of Cardiology, Heart Rhythm Society, and European Society of Cardiology guidelines for primary prevention ICD, at 12-month follow-up had LVEF >35% or NYHA Class I with LVEF of 31-35%. Those with nonischemic cardiomyopathy, defined as improved beyond American Heart Association, American College of Cardiology, Heart Rhythm Society, and European Society of Cardiology guidelines for primary prevention ICD, at 12-month follow-up had LVEF >35% or NYHA Class I and LVEF <35%. Primary endpoint was initial occurrence of appropriate ICD therapy for ventricular tachyarrhythmia including ventricular tachycardia or ventricular fibrillation. Secondary outcomes included episodes of fast ventricular tachyarrhythmia (defined as >200 bpm) and the combined endpoint of death and ventricular tachyarrhythmia.