Abstract： AIM To evaluate the effect and safety of excimer laser coronary angioplasty(ELCA)used in patients of STEMI with thrombus-rich lesions.METHODS Thirty-five patients with severe thrombosis lesions were pretreated with ELCA(n=10)or manual thrombectomy(n=25)and then they were treated with routine PCI in Fuwai Yunnan Hospital.The operative success rate was observed by TIMI flow rate,corrected TIMI frame count(cTFC),ST-segment revolution(STR)and in-hospital major adverse cardio-cerebral events(MACCEs),including cardiovascular death and MI(stent thrombosis included).Stroke was also investigated.RESULTS Compared with the thrombus aspiration group,ELCA treatment for STEMI with high thrombus burden lesions can improve postoperative cTFC(P<0.05),reduce the proportion of tirofiban use(P<0.05),and immediately implant stents more frequently than the thrombus aspiration group(P<0.05).There were no complications such as coronary dissection,perforation,slow blood flow,or reflow in the ELCA group.Two cases in the thrombus aspiration group experienced branch embolism during surgery,and there were no major cardiovascular or cerebrovascular events during hospitalization in the ELCA group.CONCLUSION The application of ELCA assisted PCI for STEMI high thrombotic burden lesions is safe and effective,and can significantly reduce related complications.