Effect of beta-blocker therapy in patients with or without left ventricular systolic dysfunction after acute myocardial infarction

This observational study aimed to investigate the association between beta-blocker therapy and clinical outcomes in patients with acute myocardial infarction (AMI), especially with mid-range or preserved left ventricular systolic function.Among 13 624 patients enrolled in the Korea Acute Myocardial Infarction Registry-National Institute of Health (KAMIR-NIH), 12 200 in-hospital survivors were selected. Patients with beta-blockers showed significantly lower 1-year major adverse cardiac events (MACE), which was a composite of cardiac death, MI, revascularization, and readmission due to heart failure [9.7 vs. 14.3/100 patient-year; hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.72-0.97; P = 0.022). However, this association had a significant interaction with left ventricular ejection fraction (LVEF). Beta-blocker therapy at discharge was associated with lower 1-year MACE in patients with LVEF ≤40% (HR 0.63, 95% CI 0.48-0.81; P < 0.001), and 40%