The CRT improved functional status in patients indicated for an ICD who also have symptomatic HF and intraventricular conduction delay.

These findings may serve as a guide to clinicians considering therapeutic options in patients who are candidates for ablation.

Background-Cardiac resynchronization therapy (CRT) alone or combined with an implantable defibrillator (CRT-D) has been shown to improve exercise capacity and quality of life and to reduce heart failure (HF) hospitalizations and mortality in patients with New York Heart Association (NYHA) class III and IV HF. There is concern that the device procedure may destabilize these very ill class IV patients. We sought to examine the outcomes of NYHA class IV patients enrolled in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) trial to assess the potential benefits of CRT and CRT-D. Methods and Results-The COMPANION trial randomized 1520 patients with NYHA class III and IV HF to optimal medical therapy, CRT, or CRT-D. In the class IV patients (nϭ217), the primary end point of time to death or hospitalization for any cause was significantly improved by both CRT (hazard ratio [