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Very Late DES thrombosis

The American Journal of Medicine study is now available and I will post the abstract below. The findings suggest that both Cypher and Taxus have a small, but likely real, frequency of late thrombosis (no big surprise). Interestingly, Taxus appears to suffer from more late thrombosis than Cypher. This is interesting, IMHO, because Taxus generally has more late loss than Cypher (less late loss could theoretically mean poorer coverage of the stent struts by neointima, perhaps increasing the risk for late thrombosis -- thus, such a mechanims for late thrombosis is not directly supported by this study). If I find anything further that is noteworthy after reading the study I'll post again.

The American Journal of Medicine
Volume 119, Issue 12 , December 2006, Pages 1056-1061

Late Thrombosis of Drug-Eluting Stents: A Meta-Analysis of Randomized Clinical Trials

Anthony A. Bavry MD, MPHa, Dharam J. Kumbhani MD, SMb, Thomas J. Helton DOa, Przemyslaw P. Borek MDa, Girish R. Mood MDa and Deepak L. Bhatt MDa, ,

aDepartment of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio
bDepartment of Internal Medicine, University of Pennsylvania, Philadelphia.

Abstract
Purpose
Drug-eluting stents are commonly used for percutaneous coronary intervention. Despite excellent clinical efficacy, the association between drug-eluting stents and the risk for late thrombosis remains imprecisely defined.

Methods
We performed a meta-analysis on 14 contemporary clinical trials that randomized 6675 patients to drug-eluting stents (paclitaxel or sirolimus) compared with bare metal stents. Eight of these trials have reported more than a year of clinical follow-up.

Results
The incidence of very late thrombosis (>1 year after the index procedure) was 5.0 events per 1000 drug-eluting stent patients, with no events in bare metal stent patients (risk ratio [RR] = 5.02, 95% confidence interval [CI], 1.29 to 19.52, P = .02). Among sirolimus trials, the incidence of very late thrombosis was 3.6 events per 1000 sirolimus stent patients, with no events in bare metal stent patients (RR = 3.99, 95% CI, .45 to 35.62, P = .22). The median time of late sirolimus stent thrombosis was 15.5 months, whereas with bare metal stents it was 4 months. Among paclitaxel trials, the incidence of very late thrombosis was 5.9 events per 1000 paclitaxel stent patients, with no events in bare metal stent patients (RR = 5.72, 95% CI, 1.08 to 32.45, P = .049). The median time of late paclitaxel stent thrombosis was 18 months, whereas it was 3.5 months in bare metal stent patients.

Conclusions
Although the incidence of very late stent thrombosis more than 1 year after coronary revascularization is low, drug-eluting stents appear to increase the risk for late thrombosis. Although more of this risk was seen with paclitaxel stents, it remains possible that sirolimus stents similarly increase the risk for late thrombosis compared with bare metal stents.