Incidence and predictors of drug-eluting stent thrombosis during and after discontinuation of thienopyridine treatment

Background - The need for prolonged aspirin and thienopyridine therapy and the risk of stent thrombosis ( ST) remain as drawbacks associated with drug- eluting stents. Methods and Results - A prospective observational cohort study was conducted between June 2002 and January 2004 on 3021 patients consecutively and successfully treated in 5389 lesions with drug- eluting stents. Detailed patient information was collected on antiplatelet therapy. We analyzed the incidence of ST throughout the 18- month follow- up period and its relationship with thienopyridine therapy. ST occurred in 58 patients ( 1.9%) at 18 months. Forty- two patients ( 1.4%) experienced the event within 6 months of stent implantation. Acute myocardial infarction ( fatal or nonfatal) occurred in 46 patients ( 79%) and death in 23 patients ( 39%) with ST. The median interval from discontinuation of thienopyridine therapy to ST was 13.5 days ( interquartile range 5.2 to 25.7 days) for the first 6 months and 90 days ( interquartile range 30 to 365 days) between 6 and 18 months. On multivariable analysis, the strongest predictor for ST within 6 months of stenting was discontinuation of thienopyridine therapy ( hazard ratio, 13.74; 95% CI, 4.04 to 46.68; P < 0.001). Thienopyridine discontinuation after 6 months did not predict the occurrence of ST ( hazard ratio, 0.94; 95% CI, 0.30 to 2.98; P = 0.92). Conclusions - Discontinuation of thienopyridine therapy was the major determinant of ST within the first 6 months, but insufficient information is available to determine whether there is benefit in continuing a thienopyridine beyond 6 months.