Predictors and Clinical Implications of Stent Thrombosis in Patients with ST-segment Elevation Myocardial Infarction: Insights from the EXAMINATION Trial

Background: Few data are available about safety of second generation drug eluting stents in an all-comer ST elevation myocardial infarction (STEMI) population. We sought to investigate the predictors and clinical implications of 1-year stent thrombosis (ST) in patients with STEMI, included in the EXAMINATION trial.

Methods And Results: The EXAMINATION trial is an all-comer prospective, randomized 1:1 controlled trial, testing everolimus-eluting stent (EES) vs. cobalt chromium bare metal stent (BMS) in STEMI patients. It included 1498 patients, randomized to EES (n = 751) or BMS (n = 747). At 1 year, definite/probable stent thrombosis, defined according to ARC criteria, occurred in 26 patients (1.73%), including 18 definite and 8 probable events. The incidence of ST was lower in patients treated with EES than in those treated with BMS (HR 0.16, 95% CI 0.03-0.29, p = 0.017). Patients with ST have higher 1-year rates of cardiac death (30.8% vs. 2.5%, p<0.001), myocardial infarction (30.8% vs. 0.5%, p<0.001) and target vessel revascularization (65.4% vs. 4.2%, p<0.001) compared with those without. Independent predictors of 1-year definite/probable ST were BMS implantation at the index procedure (HR 3.41, 95% CI 1.35-8.60), ST segment resolution of at least 70% in the EKG post-PCI (HR 0.30, 95% CI 0.13-0.70) and Killip class on admission (HR 2.57, 95% CI 1.70-3.90).

Conclusions: ST had low frequency in the first year after implantation of EES/BMS in STEMI patients, but it is associated with adverse events. BMS implantation, lack of ST-segment resolution and high Killip class on admission were independent predictors of 1-year ST.