Abstract: AIM: To study the therapeutic strategy for ST-segment elevation myocardial infarction (STEMI) in young and middle-aged patients by analyzing the characteristics of the culprit vessel revealed by coronary angiography (CAG). METHODS: A total of 224 patients with STEMI being treated at the Tangdu Hospital, Fourth Military Medical University were divided into stent group (n=160, M/F=132/28) and non-stent group (n=64, M/F=64/0) according to the characteristics of the culprit vessel in CAG 8 days after primary percutaneous transluminal coronary angioplasty (PTCA) or thrombolysis. The basic conditions, clinical manifestations, coronary lesion characteristics, predisposing factors and results of the CAG 8 days and 6 months after primary revascularization were observed and compared between groups. RESULTS: Compared with patients in the stent group, patients who had no pectoris in the non-stent group were significantly younger in age (P<0.01). There were more male patients and fewer patients with diabetes, hyperlipidemia and hypertension were observed. Fatigue and alcohol were the major predisposing factors. Results of the CAG 8 days after primary revascularization indicated that patients in the non-stent group all suffered from single-vessel coronary disease of the anterior descending branch, whereas 148 patients in the stent-implanted group suffered from multi-vessel coronary disease (P<0.01). The culprit vessel in all cases in the non-stent group reached TIMI grade 3, whereas only 88 cases in the stent group reached TIMI grade 3. Mean luminal diameter stenosis of the culprit vessel in the non-stent group was (0.37±0.10) mm, greater than in the stent group (0.82±0.08) mm, P<0.01. Results of the CAG 6 months after primary revascularization indicated that the mean luminal diameter stenosis of the culprit vessel was smaller than it was 8 days after primary revascularization in the non-stent group (P<0.01). CONCLUSION: This study suggests that stent implantation should be cautiously used in patients ≤40 years of age and with smooth luminal surface and diameter stenosis ≤50% or in patients with no other coronary lesions for stent implantation.