Abstract: Objective To investigate the effect of selective percutaneous coronary intervention(PCI) on myocardial microperfusion and prognosis in the elderly patients with acute ST segment elevation myocardial infarction (STEMI) and high thrombus burden (HTB) after thrombus aspiration and targeted intracoronary administration of recombinant human prourokinase (rhPro-UK). Methods A total of 141 elderly patients with STEMI-HTB were consecutively divided into emergency PCI group (69 cases) and delayed PCI group (72 cases). The delayed PCI group underwent selective PCI after receiving rhPro-UK to restore thrombolysis in myocardial infarction(TIMI)2-3 degree blood flow by puncturing balloon after thrombus aspiration; The emergency PCI group underwent emergency PCI after thrombus aspiration. The baseline information, intervention related indicators, myocardial microperfusion and prognosis of the two groups were compared. Results The peak value of creatine kinase myocardial isoenzyme(CK-MB), cardiac troponin I (cTnI), the number of stents implanted, the length of stents, the ratio of slow flow/no reflow, the corrected TIMI frames (cTFC) and TIMI myocardial perfusion frame count(TMPFC) in delayed PCI group were significantly lower than those in emergency PCI group (P＜0.05). At 1 month follow-up, there were no significant differences in all-cause death, stroke, target vessel revascularization(TVR) and heart failure between the emergency PCI group and the delayed PCI group (P>0.05). The level of left ventricular ejection fraction(LVEF) in the delayed PCI group one month later was significantly higher than that in the emergency PCI group (P=0.038). There were no significant differences in major and minor bleeding events between the two groups in hospital and during one month of follow-up (P>0.05). Conclusions Delayed PCI can significantly improve the myocardial microperfusion and cardiac function in the elderly patients with STEMI-HTB without an increase in major and minor bleeding.

Key words: acute ST segment elevation myocardial infarction, delayed percutaneous coronary intervention, myocardial microperfusion