Long-Term Risk of Cardiovascular Death in Patients With Mildly Reduced Ejection Fraction After Acute Myocardial Infarction: A Multicenter, Prospective Registry Study

Background: The prognostic implication of mildly reduced ejection fraction (mrEF) after acute myocardial infarction has not been clearly demonstrated. We investigated the long-term risk of cardiovascular death and its predictors in patients with mrEF following acute myocardial infarction. Methods and Results: A total of 18 668 patients who presented with acute myocardial infarction were included in 2 prospective, multicenter registries. The incidence of adverse cardiovascular events according to the left ventricular ejection fraction (EF) strata at index admission were evaluated. A score system consisting of clinical variables were developed to predict long-term cardiovascular death in the mrEF group. There were 2548 patients with reduced EF (EF <= 40%), 4266 patients with mrEF (EF 41%-49%), and 11 854 patients with preserved EF (EF >= 50%). During a median follow-up period of 37.9 months, the cardiovascular death rate was 22.3% in the reduced EF group, 10.3% in the mrEF group, and 7.3% in the preserved EF group (P<0.001). In the mrEF group, age>65 years, hypertension, stroke, severe renal insufficiency, and Killip class >= 3 were independent predictors for cardiovascular death. Presence of >2 predictors best discriminated the high-risk patients for cardiovascular death with an area under the curve of 0.746. Incidence of cardiovascular death in the high-risk mrEF group was comparable with the rEF group, while it was lower in the low-risk mrEF group than in the pEF group. Conclusions: Patients with mrEF after acute myocardial infarction had a modest risk of cardiovascular death. Clinical predictors could help discriminate a high-risk subpopulation with cardiovascular death risks comparable with those in the reduced EF group.