Objective To compare the effects and prognosis between bivalirudin and heparin on coronary microcirculation in patients with acute coronary syndrome(ACS)during percutaneous coronary intervention(PCI).Methods A retrospective analysis was conducted on 312 ACS patients who underwent PCI treatment in the Traditional Chinese Medicine Hospital Affiliated to Xinjiang Medical University from January 2020 to March 2023.General clinical data were analyzed and divided into a bivalvrudin group of 153 patients and a heparin group of 159 patients based on different anticoagulation regimens during the perioperative period.The postoperative thrombolysis in myocardial infarction(TIMI)blood flow grading,TIMI myocardial perfusion grading(TMPG),ST segment regression rate(STR)of electrocardiogram,and the number of angina pectoris episodes were observed and compared between the two groups The incidence of adverse events within 7 days after surgery,the incidence of major adverse cardiovascular events(MACE)within 3 months after surgery,and the incidence of bleeding events.Results There was no statistically significant difference in the general clinical data and intraoperative conditions between the two groups of patients(both P＞0.05).There was no statistically significant difference in TIMI blood flow grading between the two groups of patients after PCI(P=0.959).The TMPG grading of two groups of patients after PCI was statistically significant(P=0.001).The number of angina attacks and ST segment regression rate of electrocardiogram in both groups of patients after PCI were statistically significant(both P＜0.05).The incidence of adverse events within 7 days after PCI in two groups of patients was not statistically significant(P=0.285).There was no statistically significant difference in the total incidence of MACE events within 3 months after PCI between the two groups of patients(P=0.195).There was no statistically significant difference in the incidence of bleeding events within 3 months after PCI between the two groups of patients(all P＞0.05).Conclusions sivalirudin is safe and effective for PCI treatment,can improve coronary microcirculation,and does not increase the incidence of MACE events,bleeding events,and stent thrombosis events.