The introduction of the drug-eluting stent (DES) has contributed to a significant reduction in in-stent restenosis and repeat revascularization.^1,2 However, despite the use of the DES, percutaneous coronary intervention (PCI) of diffuse long coronary lesions still remains challenging because the prevalence of in-stent restenosis and stent thrombosis remains high compared with short-length coronary lesions.^3,4

Quiz Ref ID Patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) with drug-eluting stents are currently recommended dual antiplatelet therapy (DAPT), consisting of aspirin with a P2Y12 inhibitor for 12 months using a potent antiplatelet agent such as ticagrelor or prasugrel.^1-4 However, this strategy increases bleeding risk even in patients with a high thrombotic risk of ACS.^5-7 Although aspirin has proven benefits and has become the cornerstone for the antiplatelet therapy in secondary prevention of cardiovascular disease, discontinuing aspirin while maintaining administration of a P2Y12 inhibitor after DAPT was introduced to reduce the risk of bleeding.⁸ Recent randomized trials also evaluated the aspirin-free strategies with ticagrelor monotherapy.^9,10 However, an investigation of ticagrelor monotherapy after short-term DAPT focusing on the patients with ACS including ST-elevation myocardial infarction who underwent PCI with newer-generation drug-eluting stents has not been performed.

Background—: The optimal duration of dual antiplatelet therapy (DAPT) after implantation of drug-eluting coronary stents remains undetermined. We aimed to test whether 6-month DAPT would be noninferior to 12-month DAPT after implantation of drug-eluting stents. Methods and Results—: We randomly assigned 1443 patients undergoing implantation of drug-eluting stents to receive 6- or 12-month DAPT (in a 1:1 ratio). The primary end point was a target vessel failure, defined as the composite of cardiac death, myocardial infarction, or ischemia-driven target vessel revascularization at 12 months. Rates of target vessel failure at 12 months were 4.8% in the 6-month DAPT group and 4.3% in the 12-month DAPT group (the upper limit of 1-sided 95% confidence interval, 2.4%; P =0.001 for noninferiority with a predefined noninferiority margin of 4.0%). Although stent thrombosis tended to occur more frequently in the 6-month DAPT group than in the 12-month group (0.9% versus 0.1%; hazard ratio, 6.02; 95% confidence interval, 0.72–49.96; P =0.10), the risk of death or myocardial infarction did not differ in the 2 groups (2.4% versus 1.9%; hazard ratio, 1.21; 95% confidence interval, 0.60–2.47; P =0.58). In the prespecified subgroup analysis, target vessel failure occurred more frequently in the 6-month DAPT group than in the 12-month group (hazard ratio, 3.16; 95% confidence interval, 1.42–7.03; P =0.005) among diabetic patients. Conclusions—: Six-month DAPT did not increase the risk of target vessel failure at 12 months after implantation of drug-eluting stents compared with 12-month DAPT. However, the noninferiority margin was wide, and the study was underpowered for death or myocardial infarction. Our results need to be confirmed in larger trials. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00698607.