# Beta-Blocker Therapy After Myocardial Infarction: A Systematic Review and Meta-Analysis of Contemporary Randomized Controlled Trials

## TL;DR

This study reviews recent trials to determine if beta-blockers help patients after a heart attack, finding no overall benefit but possible benefits in specific groups.

## Contribution

The study provides a meta-analysis of recent trials to assess beta-blocker efficacy in post-MI patients based on MI type, LVEF, and sex.

## Key findings

- No overall significant association between beta-blocker non-use and adverse outcomes.
- Possible benefit in NSTEMI and mildly reduced LVEF subgroups.
- No clear benefit in STEMI or preserved LVEF groups.

## Abstract

The clinical benefit of beta-blocker treatment in patients with a previous myocardial infarction (MI) and without a reduced left ventricular ejection fraction (LVEF) is not established. This study aims at assessing the impact of beta-blocker treatment after an MI based on the type of MI at presentation, the LVEF, and the patient’s sex in the setting of contemporary management of MI. We searched the PubMed and Cochrane Library databases for randomized clinical trials published over last ten years that reported beta-blockers’ impact on prognosis in patients with LVEF > 40%. A meta-analysis was performed to assess the association between the beta-blocker treatment and outcomes in different patient subgroups based on the type at presentation (with ST segment elevation, STEMI, or without ST segment elevation, NSTEMI), LVEF, and sex. In the overall analysis, the association between beta-blocker non-use and the composite endpoint was not statistically significant under the random-effects model. In subgroup analyses, a higher risk with beta-blocker non-use was suggested in NSTEMI and in patients with mildly reduced LVEF in common-effect estimates (NSTEMI: RR 1.13, 95% CI 1.02–1.25; I2 18%; mildly reduced LVEF: RR 1.24, 95% CI 1.03–1.49; I2 0%), whereas corresponding random-effects estimates were not consistently significant. No clear association was observed in STEMI, preserved LVEF, or by sex. In sensitivity analyses excluding the ABYSS withdrawal trial, the overall association was attenuated and remained non-significant (random-effects RR 1.06, 95% CI 0.84–1.33; I2 35%). Long-term beta-blocker therapy after myocardial infarction showed no clear overall benefit or harm across contemporary randomized trials. Possible signals of benefit in selected subgroups warrant confirmation in adequately powered studies with standardized endpoints.