β-Blockers and Mortality After Acute Myocardial Infarction in Patients Without Heart Failure or Ventricular Dysfunction

Background: For acute myocardial infarction (AMI) without heart failure (HF), it is unclear if β-blockers are associated with reduced mortality. Objectives: The goal of this study was to determine the association between β-blocker use and mortality in patients with AMI without HF or left ventricular systolic dysfunction (LVSD). Methods: This cohort study used national English and Welsh registry data from the Myocardial Ischaemia National Audit Project. A total of 179,810 survivors of hospitalization with AMI without HF or LVSD, between January 1, 2007, and June 30, 2013 (final follow-up: December 31, 2013), were assessed. Survival-time inverse probability weighting propensity scores and instrumental variable analyses were used to investigate the association between the use of β-blockers and 1-year mortality. Results: Of 91,895 patients with ST-segment elevation myocardial infarction and 87,915 patients with non–ST-segment elevation myocardial infarction, 88,542 (96.4%) and 81,933 (93.2%) received β-blockers, respectively. For the entire cohort, with >163,772 person-years of observation, there were 9,373 deaths (5.2%). Unadjusted 1-year mortality was lower for patients who received β-blockers compared with those who did not (4.9% vs. 11.2%; p < 0.001). However, after weighting and adjustment, there was no significant difference in mortality between those with and without β-blocker use (average treatment effect [ATE] coefficient: 0.07; 95% confidence interval [CI]: −0.60 to 0.75; p = 0.827). Findings were similar for ST-segment elevation myocardial infarction (ATE coefficient: 0.30; 95% CI: −0.98 to 1.58; p = 0.637) and non–ST-segment elevation myocardial infarction (ATE coefficient: −0.07; 95% CI: −0.68 to 0.54; p = 0.819). Conclusions: Among survivors of hospitalization with AMI who did not have HF or LVSD as recorded in the hospital, the use of β-blockers was not associated with a lower risk of death at any time point up to 1 year. (β-Blocker Use and Mortality in Hospital Survivors of Acute Myocardial Infarction Without Heart Failure; NCT02786654).