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

Abstract

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).

Keywords: NSTEMI; STEMI; average treatment effect; preserved left ventricular systolic function; propensity score; survival.

Graphical abstract

Figure 1

Analytical Cohort Derivation Flowchart Strengthening the Reporting of Observational Studies in Epidemiology diagram shows the derivation of the analytical cohort from the Myocardial Ischaemia National Audit Project dataset. AMI = acute myocardial infarction; CABG = coronary artery bypass graft; NSTEMI = non–ST-segment elevation myocardial infarction; PCI = percutaneous coronary intervention; STEMI = ST-segment elevation myocardial infarction.

Figure 2

Adjusted Kaplan-Meier Survival Estimates (n = 16,683) In these adjusted survival curves according to prescription of β-blockers at discharge for the (A) AMI, (B) NSTEMI, and (C) STEMI groups, covariates and the inverse weighted propensity scores of receipt of care were adjusted for, and no statistical differences in survival were noted. Abbreviations as in Figure 1.

Central Illustration

β-Blockers and Mortality After AMI Without HF In this study, patients experiencing an acute myocardial infarction (AMI) without heart failure (HF) or left ventricular systolic dysfunction were commonly prescribed β-blockers at hospital discharge (94.8%). However, in this nationwide observational study using propensity score analysis (1-year follow-up), the use of β-blockers was not associated with a significant difference in survival times after AMI.