Carvedilol in the treatment of chronic heart failure: lessons from the Carvedilol Or Metoprolol European Trial.

Beta-blockers have been shown to improve survival in patients with chronic heart failure. The effect of different generations of beta blockers has been debated. Both metoprolol and carvedilol have demonstrated beneficial effects in placebo-controlled trials. In The Carvedilol Or Metoprolol European Trial (COMET) two beta blockers were compared in a double-blind randomized matter. This is the first direct comparison between metoprolol and carvedilol of long-term effect on survival in patients with chronic heart failure. The all-cause mortality was significantly reduced in the favour of carvedilol. The dose and formulation of metoprolol used in this trial has caused debate, and it has been questioned whether a similar beta1-blockade is obtained in the two intervention groups. At this time there is an unresolved debate as to whether carvedilol is a superior beta-blocker or whether differences in beta1-blockade explained the results of COMET.