Are beta-blockers effective in patients who develop heart failure soon after myocardial infarction? A meta-regression analysis of randomised trials

Background: The great majority of post-infarction studies of beta-blockers were conducted in an era when these agents were widely held to be contra-in dicated for the management of heart failure. We now know that beta-blockers are highly effective for the management of patients with chronic stable he art failure. However, there remains uncertainty about their role in the set ting of post-infarction heart failure and ventricular dysfunction. Aim: the primary objective in this paper, was to investigate the extent to which he art failure or evidence of major cardiac dysfuntion influenced outcome in p revious trials of beta-blockers in heart failure after myocardial infarctio n. Methods: We assessed the extent to which the inclusion of patients with heart failure or major cardiac dysfunction influenced outcome in randomised trials of long-term use of beta-blockade after myocardial infarction. The primary analysis was to assess the extent to which the proportion of patien ts included in each trial with heart failure influenced the relative odds o f all-cause mortality in the trials. All randomised trials without crossove r with treatment lasting more than one month and with 50 or more patients w ere considered. All those that provided information on the proportion of pa tients with heart failure or major cardiac dysfunction in the original or s ubsequent articles were included in the analysis. Results: Overall treatmen t with a beta-blocker was associated with a 22.6% reduction in the odds of death (95% CI 11-32.3%). There were very few data on the effects of beta-bl ockers after myocardial infarction in patients with documented left ventric ular systolic dysfuntion. In the analysis that included heart failure as a factor, treatment with a beta-blocker was associated with a non-significant interaction with the presence of heart failure. However, because the group including heart failure patients were at higher risk, the absolute benefit of treatment with beta-blockers appeared greater in this group. Conclusion s: This analysis suggests that the relative benefit of beta-blockers on mor tality after a myocardial infarction is similar in the presence or absence of heart failure but that the absolute benefit may be greater in the former . However, as current clinical practice has changed radically from the time when the majority of these trials were conducted, further trial evidence w ould be desirable. (C) 2000 Society of Cardiology. All rights reserved.