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Are beta-blockers effective in patients who develop heart failure soon after myocardial infarction? A meta-regression
T Houghton1, N Freemantle, J G Cleland
1Department of Cardiology, Castle Hill Hospital, University of Hull, HU16 5JQ, Kingston-upon-Hull, UK.
Insights
Beta-blockers reduce mortality after myocardial infarction, with similar relative benefits whether or not heart failure is present. Absolute benefits of beta-blockers may be greater in patients with heart failure post-myocardial infarction.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Beta-blockers are effective for chronic heart failure but their role post-myocardial infarction (MI) with heart failure or ventricular dysfunction is uncertain.
- Historical studies of beta-blockers post-MI were conducted when heart failure was considered a contraindication.
Purpose of the Study:
- To investigate how heart failure or cardiac dysfunction influenced outcomes in previous beta-blocker trials post-MI.
- To assess the impact of heart failure prevalence on all-cause mortality in randomized trials of beta-blockade after MI.
Main Methods:
- Systematic review of randomized trials (without crossover, >1 month duration, ≥50 patients) of beta-blockade post-MI.
- Analysis focused on the proportion of patients with heart failure or major cardiac dysfunction in each trial.
- Primary analysis examined the influence of heart failure proportion on all-cause mortality odds.
Main Results:
- Beta-blocker treatment was associated with a 22.6% reduction in all-cause mortality odds.
- Limited data existed for beta-blocker effects in patients with left ventricular systolic dysfunction post-MI.
- While the interaction between beta-blockers and heart failure was non-significant, absolute mortality benefits appeared greater in heart failure patients due to higher baseline risk.
Conclusions:
- Relative mortality benefits of beta-blockers post-MI are similar with or without heart failure.
- Absolute benefits of beta-blockers may be greater in post-MI patients with heart failure.
- Further trial evidence is needed due to significant changes in current clinical practice since the reviewed trials were conducted.
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-indicated for the management of heart failure. We now know that beta-blockers are highly effective for the management of patients with chronic stable heart failure. However, there remains uncertainty about their role in the setting of post-infarction heart failure and ventricular dysfunction.
Aim:
the primary objective in this paper, was to investigate the extent to which heart failure or evidence of major cardiac dysfunction influenced outcome in previous trials of beta-blockers in heart failure after myocardial infarction.
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 patients included in each trial with heart failure influenced the relative odds of all-cause mortality in the trials. All randomised trials without crossover with treatment lasting more than one month and with 50 or more patients were considered. All those that provided information on the proportion of patients with heart failure or major cardiac dysfunction in the original or subsequent articles were included in the analysis.
Results:
Overall treatment with a beta-blocker was associated with a 22.6% reduction in the odds of death (95% C1 11-32.3%). There were very few data on the effects of beta-blockers after myocardial infarction in patients with documented left ventricular systolic dysfunction. 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.
Conclusions:
This analysis suggests that the relative benefit of beta-blockers on mortality 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 would be desirable.