Introduction: Primary percutaneous coronary intervention (PPCI) is an effective method for the clinical treatment of acute ST-segment elevation myocardial infarction (STEMI). For patients who miss the optimal time window, optimal management of these patients remains controversial. Aim: To compare the effects of different timing of percutaneous coronary intervention on the long-term prognosis of elderly patients with acute ST-segment elevation myocardial infarction (STEMI) with time from symptom onset > 12 hours. Material and methods: Elderly acute STEMI patients with time from symptom onset > 12 hours in the period from July 2021 to July 2022 in the Department of Cardiology, Affiliated Hospital of Hebei University, were randomly divided into four groups: group 1 (immediate invasive strategy, percutaneous coronary interventions (PCI) < 24 hours after symptoms onset, n = 80), group 2 (early invasive strategy, 24-< 72 hours after symptoms onset, n = 80), group 3 (delayed invasive strategy after symptoms onset, 72-< 168 hours after symptoms onset, n = 80), and group 4 (late PCI group after symptoms onset, >= 168 hours after symptoms onset, n = 80). Primary study end points were 12-month cardiac mortality, nonfatal myocardial infarction (MI), target-vessel revascularization, and heart failure-related rehospitalization. Results: There were no significant differences between groups in cardiac mortality, nonfatal MI and target-vessel revascularization. During follow-up, heart failure-related rehospitalization was higher in group 1 than in the other groups (18.8% vs. 5.1% vs. 7.4% vs. 6.3%, p = 0.010). Compared with group 1, group 2, group 3 and group 4 had lower heart failure-related rehospitalization (HR = 0.250, Conclusions: For acute STEMI patients who missed the optimal time of PCI, immediate PCI did not reduce adverse clinical outcomes.