BACKGROUND Initial left ventricular (LV) systolic function is a main determinant of clinical outcomes in patients with acute myocardial infarction (AMI). This study was performed to investigate whether AMI patients have different prognostic factors according to their baseline LV systolic function.

METHODS A total of 12,988 patients with AMI from a nationwide database were analyzed. Major adverse cardiovascular events (MACEs) within 12months of AMI, including death, nonfatal myocardial infarction (MI), and revascularization, were assessed.

RESULTS Patients were stratified into two groups according to LV ejection fraction (LVEF): those with LVEF<40% and those with LVEF≥40%. Patients with LVEF<40% (n=1962, 15.1%) were older and had more unfavorable cardiovascular risk factors than those with LVEF≥40% (n=11,026, 84.9%). The rate of MACE was higher in patients with LVEF<40% than in those with LVEF≥40% (26.8% vs 11.4%, p<0.001). Independent predictors of 12-month MACEs in patients with LVEF≥40% were history of MI, high Killip stage, three-vessel disease, and lower renal function, which are already known as risk factors. However, diabetes mellitus (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.17-2.40; p=0.008), and the use of rennin-angiotensin system (RAS) blockers (HR, 0.63; 95% CI, 0.41-0.95; p=0.029) were independent factors for 12-month MACE in patients with LVEF <40%.

CONCLUSIONS Prognostic factors determining 12-month MACE after AMI are different according to LVEF. Management following AMI should be tailored according to their LV systolic function.