The association of left ventricular ejection fraction with clinical outcomes after myocardial infarction: Findings from the Acute Coronary Treatment and Intervention Outcomes Network (ACTION) Registry–Get With the Guidelines (GWTG) Medicare-linked database

Abstract

Little is known about the relationship between ejection fraction (EF) and clinical outcomes among older patients with myocardial infarction in contemporary clinical practice. Data on 82,558 patients 65 years or older with ST-elevation myocardial infarction or non-ST-elevation myocardial infarction who survived to hospital discharge in the ACTION Registry-GWTG (2007-2011) were linked to Medicare data. Multivariable Cox proportional hazard modeling was used to assess the association between EF reported during hospitalization and 1-year mortality, using EF as a categorical variable (≤35%, >35% and ≤45%, >45% and <55%, and ≥55%) and as a continuous variable. Secondary outcomes of interest were 1-year all-cause, cardiovascular, and heart failure readmissions. The risk of 1-year mortality was 29.0% in patients with EF ≤ 35%, compared with 13.0% in patients in the reference group, EF ≥ 55% (adjusted hazard ratio [HR] 1.58, 95% CI 1.51-1.66). Relative to patients with EF ≥ 55%, patients with EF ≤ 35% had an increased risk of 1-year all-cause readmission (adjusted HR 1.20, 95% CI 1.17-1.24), cardiovascular readmission (adjusted HR 1.36, 95% CI 1.31-1.41), and heart failure readmission (adjusted HR 2.43, 95% CI 2.28-2.60). For patients with EF ≤ 40%, the hazard of mortality increased by 26% for every 5% decrease in EF, a finding that remained after risk adjustment (adjusted HR 1.11, 95% CI 1.09-1.12). Low EF after MI remains an important risk factor for postdischarge mortality and hospital readmission, even after adjustment for patient and hospital characteristics.