[Analysis of acute myocardial infarction one month after stent implantation].

OBJECTIVE: To study the possible causes of ST-elevated acute myocardial infarction (STEAMI) occurring one month after percutaneous coronary intervention (PCI). METHODS: One hundred and ninety two patients aged from 40 - 79 years who had a successful previous PCI and also received primary PCI due to STEAMI in this hospitalization were included in this study. The AMI-related lesions and previous angiographic findings such as the number of lesions, the degree of the stenosis, the type of stents and the acute results of last PCI, etc. were recorded in detail. If the AMI-related lesion was localized in-stents or at the edge of stents (distance from the edge < or = 5 mm), it was defined as late thrombosis, otherwise it was regarded as an AMI induced by new-lesion. RESULTS: New lesions, as the cause of STEAMI, were found in 144 cases (Group A, 75%), and late thrombosis in 48 patients (Group B, 25%). There was a significant difference in the average time from previous PCI to AMI (30.1 +/- 12.4 vs. 20.3 +/- 11.9 months) between the two groups. Diabetes mellitus (DM) and drug-eluting stents (DES) utilization were associated with markedly higher morbidity of late thrombosis in adjusted logistic regression analysis [hazard ratio (HR) 3.387, 95% CI 1.053 - 10.898 and HR 5.311, 95%CI 1.066 - 26.464]. CONCLUSIONS: STEAMI occurred 1 month after PCI are more likely to be developed from previous insignificant lesions than from late thrombosis in stents. Moreover, DM and DES are associated with a high incidence of late thrombosis, which may indicate that intensive antiplatelet therapy should be considered in diabetic patients receiving PCI.