Differential Effect of β-Blockers According to Heart Rate in Acute Myocardial Infarction Without Heart Failure or Left Ventricular Systolic Dysfunction: A Cohort Study

Objective: To evaluate the effect of beta-blockers according to heart rate in patients with acute myocardial infarction (AMI) without heart failure (HF) or left ventricular systolic dysfunction (LVSD). Patients and Methods: We enrolled patients with AMI without HF or LVSD between June 1, 2003, and February 28, 2015, from Seoul National University Hospital Acute Myocardial Infarction Registry. Patients were categorized according to discharge heart rate recorded on electrocardiographs and beta-blocker use. Low heart rate was defined as less than 75 beats/min. The primary end point was 5-year all-cause mortality according to discharge heart rate and beta-blocker use. Results: Of 2271 patients, 1696 (74.7%) received beta-blockers and 1427 (62.8%) had low heart rates. At 5 years after discharge, 205 patients died. Overall, patients with low heart rates (P<.001) and those with beta-blocker treatment had lower mortality (P<.001). After adjustment for covariates, beta-blocker use was associated with 48% reduced risk for 5-year mortality in patients with high heart rates (hazard ratio, 0.52; 95% CI, 0.35-0.76), but not in those with low heart rates (P = .97). In an inverse-probability treatment-weighted cohort, beta-blocker use was also associated with improved mortality in those with a high heart rate. Findings were similar for 5-year cardiovascular mortality. Conclusion: Among survivors with AMI without HF or LVSD, beta-blocker use was associated with reduced 5-year all-cause mortality in patients who have high heart rates, but not in those with low heart rates. (C) 2019 Mayo Foundation for Medical Education and Research