Introduction:It is a hot topic of debate whether the patients have benefited from the deferred stent implantation. This study explore the most benefit from deferred stent in patients with acute ST segment elevation myocardial infarction (STEMI)and with high thrombus burden. Methods: 351 STEMI patients undergoing drug eluting stent (DES) implantation were studied. According to whether immediate stent implantation after percutaneous transluminal coronary angioplasty (PTCA), the patients were divided into immediate stent group (310 cases with thrombus load score 1.34±+0.44) and deferred stent group (41 cases with thrombus load score 3.24±0.49). In deferred stent group DES was implanted in (7.6 ± 1.4) days of continuous antithrombotic treatments after PTCA. Results: The rate of blood flow TIMI1-2 grade was 11.9% in immediate stent group and 2.4% in deferred stent group (P < 0.05). The flow TIMI 3 grade (86.8%) in immediate stent group was significantly less than that (97.6%) in deferred stent group (P < 0.05). In immediate stent group and deferred stent group the distal embolism rate was 24.8% vs 2.4% respectively (P < 0.05), and myocardial perfusion 3 grade rate was 84.5% vs 97.6% respectively (P < 0.05). The incidence of Major adverse cardiac events was 4.5% in immediate stent group and was 0% in deferred stent group. Conclusions: For STEMI patients with high thrombus load, deferred stent implantation can significantly reduce the distal embolism events and improve myocardial perfusion, protect the heart function. © 2019 A. CARBONE Editore. All rights reserved.