Plavix discontinuation and stent thrombosis: new study with 18-month follow-up further defines the association. August 8, 2007.
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August 5, 2007 By Benjamin A. Olenchock, M.D. Ph.D. [1]
Italy A new study of over 3000 patients who received drug-eluting stents has further defined the incidence of stent thrombosis and the temporal relationship between discontinuation of thienopyridine treatment (e.g. Plavix) and stent thrombosis. The new study, published online in the journal Circulation, questions whether continuing dual anti-platelet therapy with aspirin and thienopyridine is beneficial after the first 6 months post-procedure.
Drug-eluting stents have been a major advance in the treatment of coronary artery disease, greatly decreasing the incidence of restenosis, or narrowing, of the coronary lesion. Patients with stent restenosis typically present with angina and require another revascularization procedure. Over the past few years, it has become clear that drug-eluting stents have a very small but persistent risk of thrombosis, or blood clot formation within the stent. In contrast to restenosis, stent thrombosis is a devastating event that presents as myocardial infarction or sudden death. This infrequent but potentially deadly complication had led many clinicians to continue dual anti-platelet medicines for a longer period of time, or indefinitely, in patients who have received a drug-eluting stent. The exact association between discontinuation of anti-platelet medicines and stent thrombosis is not known.
Investigators in Italy and Germany followed 3021 patients who received drug eluting stents for 5389 coronary lesions. The cumulative incidence of stent thrombosis (ARC definite or probable) was 1.9%, slightly higher than what was observed in other published studies. Over half of the stent thromboses occurred within the first month after implantation. For the first 6 months of follow-up, the best predictor of stent thrombosis was thienopyridine discontinuation, with the median time interval between discontinuation and stent thrombosis being 13.5 days. There was no association, however, between thienopyridine discontinuation and stent thrombosis occurring 6-18 months post-PCI (HR 0.94, p = 0.92). Additionally, the median time between thienopyridine discontinuation and stent thrombosis was 90 days (range 30-365) for these late events, which brings into question a causal relationship.
These data reinforce the importance of continuing dual anti-platelet therapy for at least 6 months after placement of a drug-eluting coronary stent. It appears from this study that the benefit of continuing thienopyridines more than 6 months post-procedure is reduced, perhaps reflecting improved endothelialization of stents by this time. More research is needed in order for physicians to be able to tailor the length of dual anti-platelet treatment to individual patients. Ongoing large patient registries should identify patient or stent characteristics that predict thrombotic and bleeding risks.
<biblio> Flavio Airoldi, Antonio Colombo, Nuccia Morici, Azeem Latib, John Cosgrave, Lutz Buellesfeld, Erminio Bonizzoni, Mauro Carlino, Ulrich Gerckens, Cosmo Godino, Gloria Melzi, Iassen Michev, Matteo Montorfano, Giuseppe Massimo Sangiorgi, Asif Qasim, Alaide Chieffo, Carlo Briguori, and Eberhard Grube. 2007. Incidence and Predictors of Drug-Eluting Stent Thrombosis During and After Discontinuation of Thienopyridine Treatment. Circulation in press. </biblio>
