Background— The objective was to evaluate the role of risk factors and stent type for stent thrombosis (ST) using a large real world registry.

Methods and Results— We evaluated all consecutive coronary stent implantations in Sweden from May 1, 2005, to June 30, 2007. All cases of ST, documented in the Swedish coronary angiography and angioplasty registry until September 21, 2008, were analyzed. ST was registered in 882 of 73 798 stents. Acute coronary syndromes, insulin-treated diabetes mellitus, smoking, previous coronary intervention, warfarin treatment, small stent diameter, and stenting in restenotic, complex, or bypass graft lesions had the strongest association with ST in the multivariable statistical model. There were considerable differences in the frequency of ST between different stent brands. The overall risk of ST was lower in drug-eluting stents compared with bare metal stents (adjusted risk ratio, 0.79; 99% CI, 0.63 to 0.99). However, from 6 months after stent implantation and onward, the risk for ST was higher in drug-eluting stents compared with bare metal stents (adjusted risk ratio, 2.02; 99% CI, 1.30 to 3.14).

Conclusions— ST is a multifactor disease, and the incidence varies considerably between patients based on clinical, vessel, and stent characteristics. For drug-eluting stents compared with bare metal stents, the risk pattern was biphasic; initially, bare metal stents demonstrated a higher risk of ST; whereas after the first months, ST risk was higher with drug-eluting stents. Our findings highlight the need for prospective randomized studies with head-to-head comparisons between different stents.