Importance
Despite antirestenotic efficacy of coronary drug-eluting stents (DES) compared with bare metal stents (BMS), the relative risk of stent thrombosis and adverse cardiovascular events is unclear. Although dual antiplatelet therapy (DAPT) beyond one year provides ischemic event protection following DES, ischemic event risk is perceived to be less following BMS and the appropriate duration of DAPT following BMS is unknown.
Objective
To compare: (1) rates of stent thrombosis and major adverse cardiac and cerebrovascular events (MACCE; composite of death, myocardial infarction, or stroke) after 30 vs. 12 months of thienopyridine in patients treated with BMS taking aspirin; and (2) treatment duration effect within the combined cohorts of randomized DES or BMS-treated patients as prespecified, secondary analyses of the Dual Antiplatelet Therapy Study.
Design, Setting, Participants
International, multicenter, randomized, double-blinded, placebo-controlled trial, comparing extended (30 months) thienopyridine versus placebo in aspirin-treated patients who completed 12 months of DAPT without bleeding or ischemic events post-stenting. Study initiation August 2009 with last follow-up visit May 2014.
Exposure/Intervention
Continued thienopyridine or placebo at months 12-30 after stenting, in 11648 randomized patients treated with aspirin, of whom 1687 received BMS and 9961 DES.
Main Outcome and Measures
Stent thrombosis, MACCE, moderate/severe bleeding.
Results
Among 1687 BMS-treated patients randomized to continued thienopyridine vs. placebo, rates of stent thrombosis were 0.5% vs. 1.11%, (N=4 vs. 9, hazard ratio 0.49, 95% CI 0.15-1.64, P=0.24), MACCE 4.04% vs. 4.69%, (N=33 vs. 38, hazard ratio 0.92, 95% CI 0.57-1.47, P=0.72) and moderate/severe bleeding 2.03% vs. 0.90% (N=16 vs. 7, P=0.07), respectively. Among all 11,648 randomized patients (both BMS- and DES-treated), stent thrombosis rates were 0.41% vs. 1.32%, (N=23 vs. 74, hazard ratio 0.31, 95% CI 0.19-0.50, P<0.001), MACCE 4.29% vs. 5.74% (N=244 vs. 323, hazard ratio 0.73, 95% CI 0.62-0.87, P<0.001), and moderate/severe bleeding 2.45% vs. 1.47% (N=135 vs. 80, P<0.001).
Conclusions and Relevance
Among patients undergoing coronary stenting with BMS and who tolerated 12 months of thienopyridine, continuing thienopyridine for an additional 18 months compared with placebo did not result in statistically significant differences in rates of stent thrombosis, MACCE, or moderate/severe bleeding. However, the BMS subset may have been underpowered to identify such differences and further trials are suggested. (DAPT ClinicalTrials.gov number NCT00977938).
