BACKGROUND: ST-segment elevation myocardial infarction (STEMI) is a common and severe form of acute myocardial infarction (AMI). OBJECTIVES: The study aimed to investigate the relationship between serum nitric oxide (NO) and endothelin-1 (ET-1) levels with the severity of STEMI and their predictive value for major adverse cardiovascular events (MACE) within one year after percutaneous coronary intervention (PCI) in STEMI patients. METHODS: The retrospective study was conducted on 269 STEMI patients who underwent PCI. The patients were categorized into two groups: those who developed MACE (112 cases) and those who did not (157 cases) within one year. NO and ET1 levels were measured in collected serum using enzyme-linked immunosorbent assay. Receive-operating characteristics (ROC) curve was used to analyze the prognostic potential of NO and ET1 individually and in combination, p<
0.05 was considered statistically significant. RESULTS: Significant differences were noted between the two groups concerning age, Killip classification, left ventricular ejection fraction, cardiac troponin I (cTnI), creatine kinase-MB (CK-MB), as well as serum NO and ET-1 levels. The study observed that patients who developed MACE had lower serum NO and higher ET-1 levels upon admission. Further analysis revealed a significant inverse relationship between serum NO and ET-1 levels and the severity of myocardial infarction. A combined detection model, -0.082 * NO + 0.059 * ET-1, demonstrated promising prognostic value for the occurrence of MACE within one year post-PCI. CONCLUSIONS: Serum NO and ET-1 levels serve as valuable prognostic markers for MACE in STEMI patients undergoing PCI, exhibiting a strong correlation with AMI severity.