β-blockers are guideline-recommended for patients with myocardial infarction (MI) and left ventricular ejection fraction (LVEF) <40%. However, their role in patients with preserved or mildly reduced systolic function remains uncertain. This meta-analysis published in the Canadian Journal of Cardiology assessed outcomes of β-blocker therapy in patients with MI and LVEF >40%.

Randomized clinical trials published after 2000 were identified from PubMed, Embase, and CENTRAL. Five trials including 19,826 patients met inclusion criteria. Among them, 9,892 (49.8%) were randomized to β-blockers and 9,934 (50.2%) to no β-blocker therapy. All trials enrolled patients with MI and LVEF >40%. Hazard ratios (HR) and risk ratios (RR) with 95% confidence intervals (CI) were estimated using meta-analytic methods.

β-blockers were not associated with significant reductions in all-cause mortality (HR 0.98; 95% CI 0.85-1.13), cardiac mortality (HR 1.16; 95% CI 0.89-1.51), unplanned coronary revascularization (HR 1.01; 95% CI 0.87-1.17), or malignant ventricular arrhythmia (RR 0.87; 95% CI 0.51–1.48). There was a trend toward lower MI (HR 0.88; 95% CI 0.77-1.00) and new-onset heart failure (HF) (HR 0.82; 95% CI 0.63-1.07). β-blockers were not associated with increased symptomatic atrioventricular block (HR 1.06; 95% CI 0.83–1.34) or stroke (RR 1.16; 95% CI 0.90–1.48).

In patients with MI and LVEF >40%, β-blockers were not associated with a significant effect on any evaluated outcome. β-blockers were associated with a trend toward lower MI and HF.