Effect of carvedilol on survival in severe chronic heart failure

Objectives—To determine the effect of the β blocker carvedilol on the survival and hospitalisation of patients with severe heart failure.

Method—A double blinded, randomised controlled trial comparing carvedilol and placebo. A total of 2289 patients with symptoms of heart failure (New York Health Association class IV) were treated for a mean of 10.4 months (1156 with carvedilol versus 1133 with placebo). Standard therapy for heart failure was also continued during this period.

Results—The trial was terminated early because of the significant benefits seen in the carvedilol group during interim analysis. A total of 190 patients died in the placebo group and 130 in the carvedilol group, resulting in a 35% decrease in risk of death with carvedilol (95% CI 19%, 48%, p = 0.00013). Altogether 507 patients died or were hospitalised in the placebo group and 425 in the carvedilol group, resulting in a 24% reduction in the combined end point with carvedilol (95% CI 13%, 33%, p < 0.001). These results were valid regardless of sex, age, cause of heart failure, ejection fractions and recent frequent hospitalisations.

Conclusions—There are long term benefits in patients with severe chronic heart failure treated with carvedilol.

Critique—Many emergency physicians were trained during an era when β blockers were contraindicated in heart failure. This is yet another study showing favourable effects of β blockers in heart failure. Appraisal of this paper in terms of internal validity reveals insufficient details about the randomisation process. The paper is double blinded but bias may have inevitably occurred as patients in the carvedilol group will have had slower pulse rates. Calculations were performed with intention to treat analysis, which took into account the drop outs from the study. There is a power calculation but the trial ended early, which suggests either poor estimations …