Do beta-blockers prolong survival in chronic heart failure? A review of the experimental and clinical evidence

The results of both experimental studies and clinical trials indicate that prolonged activation of the sympathetic nervous system can adversely affect the course of heart failure, and that this deleterious effect can be attenuated with the use of beta-blocking agents. Studies with beta-1 selective agents such as metoprolol and bisoprolol, have demonstrated that beta-blockers can reduce the risk of worsening heart failure but have shown little or equivocal effect on survival. In contrast, recent trials with nonselective vasodilating beta-blockers (i.e. carvedilol) have reported a reduction in the risk of both death and hospitalization. It is uncertain, however, whether these survival effects represent a class effect of beta-blockers or a specific effect of carvedilol. Carvedilol antagonizes several biological mechanisms (not blocked by metoprolol or bisoprolol) that may be important in mediating the progression of heart failure. In three meta-analyses, the survival effects of non-selective vasodilating beta-blockers (primarily carvedilol) were greater than those of beta-1 selective non-vasodilating beta-blockers. A clear answer to the question as to whether mortality reduction is a class effect of beta-blockers will be provided by several large-scale survival trials, which are currently in progress.