OBJECTIVE: Compared with intravenous injection

to probe into the effect of coronary arterial injection of tirofiban on microvascular occlusion in patients with ST-elevated myocardial infarction（ STEMI） undergoing percutaneous coronary intervention（ PCI）. METHODS: Totally 378 STEMI patients undergoing PCI admitted into the First Hospital of Qinhuangdao City from Dec. 2017 to Nov. 2019 were selected and divided into intravenous administration group and coronary arterial administration group via random number table

with 189 cases in each group.The coronary arterial administration group was given tirofiban through suction tube after surgery

with a dosage of 10μg/kg

followed by continuous intravenous administration at a maintenance dose of 0. 15 μg/（ kg·min） for 24-48 h.The intravenous administration group was first received intravenous tirofiban at a dose of 10 μg/kg

followed by continuous intravenous administration at a maintenance dose of 0. 15 μg/（ kg·min） for 24-48 h. The baseline clinical indicators

cardiac magnetic resonance before treatment and at 6 months after treatment were collected and compared between two groups; the incidence of major adverse cardiac events（ MACE） was compared between two groups after 1 year of treatment. Multivariate logistic regression analysis was used to evaluate the factors associated with the occurrence of MACE. RESULTS: After PCI

compared with intravenous administration group

the left ventricular ejection fraction（ LVEF） of patients in the coronary arterial administration group was significantly increased（ t = 3. 351

P = 0. 001）

and the incidence of microvascular occlusion was significantly decreased（ χ2= 15. 377

P<0. 001）; after1-year follow-up

the left ventricular end-diastolic volume index（ t = 4. 591

P < 0. 001）

left ventricular end-systolic volume index（ t = 8. 622

P < 0. 001） and infarct size（ t = 10. 664

P < 0. 001） of patients in the coronary arterial administration group were significantly decreased

and the LVEF was significantly increased（ t = 4. 366

P < 0. 001）

with statistically significant differences. Coronary artery injection of tirofiban was an independent protective factor against MACE in STEMI patients at 1 year after PCI（ OR = 0. 423

95% CI = 0. 190-0. 943

P = 0. 036）.CONCLUSIONS: Compared with intravenous injection of tirofiban

coronary artery injection of tirofiban can significantly improve the incidence of MVO and remodeling of left ventricle in patients with STEMI within 6 months after PCI

and reduce the incidence of MACE events at 1 year after surgery.