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Cardiac Resynchronization Therapy Faces the Morbidity-Mortality Test

In patients with chronic systolic heart failure and intraventricular conduction delays, cardiac resynchronization therapy (CRT) has been shown to improve quality of life, functional status (i.e., NYHA class), exercise capacity, and cardiac structure and function, while limiting hospitalization for worsening heart failure (Journal Watch Cardiology Jul 26 2002). Now, in a study sponsored by a CRT-system manufacturer, researchers have zeroed in on CRT's effects on morbidity and mortality.

The researchers randomized 1520 patients with advanced chronic heart failure, in unblinded fashion, to one of three treatments in a 1:2:2 ratio: optimal medical therapy (OMT) alone, OMT plus CRT, and OMT plus CRT plus implantable-cardioverter defibrillator (ICD) therapy. The subjects' mean age was 67, 67% were men, 86% were in NYHA class III, and 55% had ischemic cardiomyopathy; mean LV ejection fraction was 21%, and mean QRS duration was 160 msec.

The 1-year composite rate of all-cause mortality and all-cause hospitalization (the primary endpoint) was 56% both with OMT+CRT and with OMT+CRT+ICD, significantly lower than the 68% rate with OMT alone. A similar pattern was found for the secondary endpoints of all-cause mortality or cardiovascular hospitalization and all-cause mortality or heart-failure hospitalization. For all-cause mortality as a solitary endpoint, OMT+CRT+ICD therapy had a significant advantage (hazard ratio, 0.64) and OMT+CRT therapy had a marginally significant advantage (HR, 0.76) over OMT alone. In both CRT groups, advantages in exercise capacity, functional status, and quality of life confirmed findings from previous CRT trials.

Comment: This trial, known by the acronym COMPANION, confirms positive findings for CRT in patients with chronic heart failure. More importantly, it represents the first adequately powered randomized assessment of the effects of CRT and CRT+ICD therapy on morbidity and mortality. Taken together with previous studies, COMPANION supports the use of CRT, with or without an ICD, as routine therapy for eligible patients. Precisely which patients with indications for CRT also should get an ICD must be the subject of further study, but existing evidence certainly supports CRT+ICD therapy in patients who have separate indications for each.

— William T. Abraham, MD

Published in Journal Watch Cardiology December 31, 2004

Citation(s):

Bristow MR et al. for the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Investigators. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med 2004 May 20; 350:2140-50.

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• Medline abstract (Free)

Rogers JG and Cain ME. Electromechanical associations. N Engl J Med 2004 May 20; 350:2193-5.

• Original article (Subscription may be required)
• Medline abstract (Free)