While clinical benefits of beta-blockers are well-established in patients with acute myocardial infarction and reduced left ventricular ejection fraction (< 40%) (AMI-rEF), but their efficacy in patients with low heart rates (H-Rs) remains unclear. This study aimed to evaluate the association between beta-blockers and 3-year mortality outcomes according to H-R in this population. We analyzed 2,941 patients with AMI-rEF from two nationwide Korean registries, stratified by discharge H-R (< 75 or ≥ 75 beats per minute). The primary outcome was 3-year all-cause death. Propensity score matching and multivariable Cox models adjusted for baseline differences. On unadjusted analysis, beta-blocker use was associated with lower all-cause death (16.1% vs. 23.3%; hazard ratio HR, 0.63; 95% confidence interval CI, 0.52–0.76) and cardiac death (9.8% vs. 15.2%; HR, 0.59; 95% CI, 0.47–0.75). However, after adjustment, these associations were attenuated. Beta-blockers were associated with a significantly increased risk of nonfatal myocardial infarction (HR, 2.29; 95% CI, 1.14–4.59), particularly in patients with discharge H-R ≥ 75 bpm (HR, 3.34; 95% CI, 1.13–9.92). In patients with AMI-rEF, beta-blockers were not independently associated with significantly reduced all-cause death after adjustment, though a trend was observed. Notably, beta-blocker use increased the risk of nonfatal myocardial infarction, particularly at higher H-R. These findings suggest that the benefits of beta-blockers in this population may not be uniform and highlight the potential importance of H-R as a clinical marker to guide individualized beta-blocker use in the contemporary post-AMI setting.
Oh et al. (Thu,) studied this question.