Abstract
BACKGROUND: There is conflicting literature on the relationship between prolonged QRS duration (QRSd) and arrhythmic events, including sudden cardiac death (SCD), in heart failure patients with or without implantable cardioverter-defibrillators (ICDs). OBJECTIVE: The purpose of this study was to evaluate the prognostic significance of prolonged QRSd relative to arrhythmic outcomes in medically and ICD-treated patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II. METHODS: Using a Cox proportional hazards model adjusting for ejection fraction, heart failure class, and blood urea nitrogen, we estimated the association of prolonged QRSd >/=140 ms with SCD in the medically treated arm and SCD or first appropriate ICD therapy for rapid ventricular tachycardia/fibrillation (VT/VF; cycle length