Aim To investigate the effect of non-infarct-related vessels chronic total occlusion (CTO) on the prognosis of elderly patients with acute ST-segment elevation myocardial infarction (STEMI) and related risk factors. Methods 210 elderly patients with STEMI who underwent percutaneous coronary intervention (PCI) in our hospital from March 2015 to June 2018 were included as the study subjects. Clinical data were compared between non-infarct-related vessels CTO patients (CTO group, n＝30) and non-infarct-related vessels non-CTO patients (non-CTO group, n＝180).The follow-up period was 12 months. Cox regression analysis was used to analyze the relevant risk factors affecting the clinical prognosis of patients. Results The in-hospital mortality and one-year mortality after operation in CTO group were significantly higher than those in non-CTO group (16.67% vs 6.11%, P＝0.03; 20.00% vs 8.39%, P＝0.03). Cox regression analysis showed that age, diabetes mellitus, lower left ventricular ejection fraction, cardiogenic shock and left anterior descending artery infarction were independent risk factors for in-hospital and one-year post-operative deaths in elderly STEMI patients. Complication of non-infarct-related vessels CTO was an independent risk factor for in-hospital mortality. Renal insufficiency and multi-vessel lesions were independent risk factors for 1-year mortality. ConclusionNon-infarct-related vessels CTO predicts poor short-term prognosis or increased risk of death in elderly STEMI patients after PCI.