Predictors and Long‐Term Clinical Impact of Heart Failure With Improved Ejection Fraction After Acute Myocardial Infarction

Background Little is known about the characteristics and long‐term clinical outcomes of patients with heart failure with improved ejection fraction (HFimpEF) after acute myocardial infarction. Methods and Results From a multicenter, consecutive cohort of patients with acute myocardial infarction undergoing percutaneous coronary intervention, patients with an initial echocardiogram with left ventricular ejection fraction ≤40% and at least 1 follow‐up echocardiogram after 14 days and within 2 years of the initial event were considered for analyses. HFimpEF was defined as an initial left ventricular ejection fraction ≤40% and serial left ventricular ejection fraction >40% with an increase of ≥10% from baseline at follow‐up. Independent factors predicting HFimpEF were identified, and clinical outcomes of patients with HFimpEF were compared with those without improvement. From an initial cohort of 10 719 patients with acute myocardial infarction, 191 patients with HFimpEF and 256 patients with non‐HFimpEF who had initial and follow‐up echocardiographic data were analyzed. The median follow‐up duration was 4.5 (interquartile range, 2.9–5.0) years. The factors predicting HFimpEF were lower peak creatine kinase myocardial band, smaller left ventricular dimensions, lower ratio between early mitral inflow velocity and mitral annular early diastolic velocity ′, and the use of β blockers or renin–angiotensin system blockers at discharge. HFimpEF was associated with a significantly decreased risk of all‐cause death compared with non‐HFimpEF (hazard ratio, 0.377 [95% CI, 0.234–0.609]; P