Elsevier

American Heart Journal

Volume 178, August 2016, Pages 65-73
American Heart Journal

Clinical Investigation
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

https://doi.org/10.1016/j.ahj.2016.05.003Get rights and content

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.

Section snippets

Study population

The NCDR ACTION Registry–GWTG is a national quality improvement initiative that focuses on STEMI and NSTEMI patients. The ACTION Registry–GWTG is an initiative of the American College of Cardiology Foundation and the American Heart Association, with partnering support from the Society of Chest Pain Centers, the American College of Emergency Physicians, and the Society of Hospital Medicine. No extramural funding was used to support this work. The authors take sole responsibility for the study

Results

Among 82,558 patients in the study, 30.6% (n = 25,251) presented with STEMI and 69.4% (n= 57,307) presented with NSTEMI. The baseline characteristics of the study population, stratified by EF categories, are detailed in Table I. Patients in lower EF categories were older and more likely to be male and to have comorbid diabetes, chronic lung disease, antecedent MI, and heart failure. Patients in lower EF categories were less likely to receive reperfusion for STEMI or revascularization for NSTEMI.

Discussion

The key finding in this large, contemporary study of clinical outcomes after MI in older patients who survive to hospital discharge is that lower EF remains a robust predictor of risk of death and hospital readmission in the first year after MI. The association between EF and the risk of death remained significant even after extensive risk factor adjustment. The present findings add to the prior body of literature on the association between EF and post-MI outcomes, and are particularly relevant

Conclusions

Among older patients presenting with MI, low EF remains an important risk factor for postdischarge mortality and hospital readmission, even after extensive adjustment for patient and hospital characteristics. Nearly 30% of older patients presenting with MI and EF ≤ 35% died and more than half were readmitted to the hospital in the year after the index admission for MI.

Acknowledgments

This research was supported by the American College of Cardiology Foundation's National Cardiovascular Data Registry (NCDR). The views expressed in this presentation represent those of the authors and do not necessarily represent the official views of the NCDR or its associated professional societies identified at CVQuality.ACC.org/NCDR.

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    Jeroen J. Bax, MD, PhD served as guest editor for this article.

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