Effect of stent thrombosis on the risk-benefit balance of drug-eluting stents and bare metal stents.

INTRODUCTION AND OBJECTIVES: To determine the difference in the risk of stent thrombosis between drug-eluting stents (DES) and bare-metal stents (BMS) and to assess the clinical implications. METHODS: A retrospective analysis of two cohorts of patients treated at our center with either > or =1 paclitaxeleluting stents (PES) (n=430) or > or =1 BMSs (n=1230) during 2003-2004 was carried out using propensity score methods to compare the adjusted risks of stent thrombosis, instent restenosis, cardiovascular death, acute myocardial infarction (AMI), and target-lesion revascularization with the two stent types. RESULTS: After a median follow-up of 46 months, there was a higher risk of stent thrombosis in PESs (hazard ratio [HR]=3; 95% confidence interval [CI], 1.2-7.1] though the risk of in-stent restenosis was lower (HR=0.3; 95% CI, 0.2-0.7]. There was no difference in the risk of cardiovascular death, AMI or target-lesion revascularization. With PESs, the risks of target-lesion revascularization (HR=0.33; 95% CI, 0.2-0.7) and in-stent restenosis (HR=0.32; 95% CI, 0.2-0.7) were reduced during the first year of follow-up. After this time, the risks of target-lesion revascularization (HR=1.8; 95% CI, 1-3.2) and very late stent thrombosis (HR=12.8; 95% CI, 3-55.1) both increased. CONCLUSIONS: Our findings indicate that the balance of risks and benefits of PESs compared with BMSs is different in the early and late periods after stent implantation. The greatly increased risk of very late stent thrombosis in PESs could cancel out the clinical benefits associated with the reduction in in-stent restenosis observed in PESs relative to BMSs.