Carvedilol has a greater survival benefit than metoprolol for patients with chronic heart failure, according to study findings in the July 5th issue of the Lancet. The Carvedilol or Metoprolol European Trial (COMET) involved over 3000 patients who were randomized to 1 of the 2 beta blockers in a multicenter, double-blind trial for roughly 5 years.

Beta blockers reduce mortality in patients who take optimal doses of diuretics and angiotensin converting enzyme inhibitors for chronic heart failure (or, as close to optimal as tolerance allows). In the current study, 3029 such patients with chronic heart failure (New York classes II to IV, ejection fraction less than 35 percent) were assigned to receive twice-daily doses of carvedilol or metoprolol for a mean follow-up of 58 months.

The differences in mortality among the 2 patient groups were striking: All-cause mortality was 34 percent for the carvedilol patients and 40 percent for the patients on metoprolol. Reduction of all-cause mortality was consistent across patient subgroups. The composite endpoint of mortality or all-cause hospital admission was 74 percent for the 1511 patients on carvedilol and 76 percent for the 1518 patients on metoprolol.

There was no statistical difference in incidence of significant side effects and withdrawals from beta blocker between the 2 treatment arms.

In an accompanying commentary, Henry Dargie, MD, discussed the current study and another study appearing in the same issue (the CHRISTMAS trial, whose investigators concluded that the positive effect of carvedilol on ejection fraction might reflect improved function of ischemic myocardium, hibernating myocardium, or both).

He concluded, “COMET and CHRISTMAS are very different trials but together they provide further insights into the benefits of beta blockade in heart failure. They are also timely, because although the history of beta blockers in heart failure is one of sustained revelation and success, their uptake in clinical practice is disappointing...Action is required if the results of clinical research are to be translated into clinical practice.”