Abstract
Background: This study was conducted to address the lack of reports comparing the clinical outcomes of non-ST-segment elevation myocardial infarction (NSTEMI) and STEMI based on left ventricular ejection fraction (LVEF). Methods: A total of 9854 patients from the Korea Acute Myocardial Infarction Registry-National Institute of Health dataset were classified into three LVEF categories: heart failure (HF) with reduced ejection fraction (EF) (HFrEF, n = 1250), HF with mildly reduced EF (HFmrEF, n = 2383), and HF with preserved EF (HFpEF, n = 6221). Each group was further divided into NSTEMI and STEMI groups. The primary clinical outcome was the incidence of patient-oriented composite outcomes, defined as all-cause death, recurrent myocardial infarction, any repeat coronary revascularization, hospitalization for HF, and stroke. Results: Following adjustment, in-hospital mortality rates were comparable between the NSTEMI and STEMI groups in the HFrEF and HFmrEF groups. However, 3-year mortality rates were higher in the NSTEMI group. In contrast, in the HFpEF group, the STEMI group had higher rates of in-hospital all-cause death (p = 0.001) and cardiac death (p < 0.001) compared to the NSTEMI group, which was associated with increased 3-year all-cause death (p = 0.026) and cardiac death (p < 0.001) in the STEMI group. When in-hospital mortality was excluded, no difference in 3-year mortality rates was observed between the NSTEMI and STEMI groups in the HFpEF group. Conclusions: In-hospital mortality and 3-year outcomes varied across LVEF groups. Therefore, comparing NSTEMI and STEMI based on LVEF provides valuable insights into the differences in patient outcomes.