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.

BACKGROUND: Little is known about the relationship between ejection fraction (EF) and clinical outcomes among older patients with myocardial infarction in contemporary clinical practice.

METHODS: 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.

RESULTS: 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).

CONCLUSIONS: Low EF after MI remains an important risk factor for postdischarge mortality and hospital readmission, even after adjustment for patient and hospital characteristics.