BACKGROUND: Previous meta-analyses have demonstrated that b-blockers reduce morbidity (symptoms, left ventricular function, and rate of hospitalization) and mortality (cardiovascular and total) in patients with congestive heart failure (CHF). The authors of this meta-analysis explored differences in effectiveness between vasodilating and nonvasodilating agents and defined differences in outcomes related to the underlying cause of CHF.
POPULATION STUDIED: A total of 5849 patients (79% men) were studied for a median duration of 6 months. Approximately 50% received b-blockers. Both vasodilating b-blockers (carvedilol and bucindolol) and nonvasodilating b-blockers (metoprolol, bisoprolol, and propranolol) were used for patients with primarily class II and III heart failure. Most patients also received angiotensin-converting enzyme inhibitors, diuretics, and digitalis.
STUDY DESIGN AND VALIDITY: The authors of this meta-analysis combined the results of 21 randomized controlled trials comparing the various b-blockers with placebo. All studies evaluated mortality on an intention-to-treat basis.
OUTCOMES MEASURED: The primary outcomes were total and cardiovascular mortality (including death due to CHF, sudden death, myocardial infarction, and other cardiovascular causes) and hospitalizations. Outcomes were evaluated on the basis of the use of vasodilating and nonvasodilating b-blockers and the underlying cause of CHF (ischemic heart disease vs nonischemic heart disease).
RESULTS: b-blockers as a group reduced total mortality in patients with CHF (10.6% vs 16.6%, relative risk [RR]=0.71; 95% confidence interval [CI], 0.63-0.80; number needed to treat [NNT]=17). A similar benefit was demonstrated in cardiovascular mortality (9.0% vs 13.7%, RR=0.71; 95% CI, 0.59-0.86; NNT=21). The reduction in cardiovascular mortality was mainly because of a significant reduction in death due to CHF and sudden death.
b-blockers are effective in reducing total and cardiovascular mortality in patients with CHF. In this meta-analysis, vasodilating b-blockers (carvedilol and bucindolol) offered a greater reduction in total mortality, but all agents affected cardiovascular mortality similarly. Patients with CHF not due to ischemic heart disease lived longer when given vasodilating b-blockers. However, this meta-analysis did not include a recently published major trial, and no studies have directly compared one b-blocker with another. b-blockers are helpful for patients with heart failure, but more research is needed to differentiate effectiveness among the various agents.