Introduction: The American Heart Association and European Society of cardiology guidelines reclassified heart failure according to left ventricular ejection fraction, recognizing patients with mid-range EF (mrEF; 40% to 49%) as a distinct group. However, studies on the clinical characteristics of mid-range EF patients and the occurrence of cardiovascular events in acute MI patients are insufficient. Methods: We categorized 6,553 patients with acute myocardial infarction (AMI) from the Korea AMI-National Institutes of Health between November 2011 and December 2015 into three groups (reduced EF ; LVEF < 40% at admission, mild-reduced EF ; LVEF 40 to 49%, preserved EF ;LVEF ≥50%). The primary endpoint was defined as any death at two-year. Secondary endpoints were defined as any myocardial infarction, any revascularization, patient-oriented composite outcome(POCE). Results: Compared to patients with other two groups, the reduced EF group had a highest overall mortality, POCE, and any MI (24.7% vs 8.3% vs 4.6%, p < 0.0001, 33.0% vs 15.6% vs 12.4%, p<0.0001, 3.9% vs 2.7% vs 2.6%, p<0.0046). When mid-range EF group was designated as a reference, in multivariate analysis including all variables, significant differences with HFrEF group was found. (Hazard ratio ). When compared with HFpEF, only Model 1 and Model 2 showed a significant statistical difference (Model 1 ; 0.65 (0.53-0.81), Model 2 ; 0.56 (0.56-0.86). Conclusions: Followed up for two years, significant differences in survival rates were observed between the mid-range EF, reduced EF, and preserved EF group. After adjusting for common prognostic factors affecting the overall mortality rate, the reduced EF group had a significantly higher mortality rate than mid-range EF group, but no significant difference was observed between the preserved EF and the mid-range EF group.