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Summary Background Current guidelines recommend dual antiplatelet therapy (DAPT) of aspirin plus a P2Y12 inhibitor for at least 12 months after implantation of drug-eluting stents (DES) in patients with acute coronary syndrome. However, available data about the optimal duration of DAPT in patients with acute coronary syndrome undergoing percutaneous coronary intervention are scant. We aimed to investigate whether a 6-month duration of DAPT would be non-inferior to the conventional 12-month or longer duration of DAPT in this population. Methods We did a randomised, open-label, non-inferiority trial at 31 centres in South Korea. Patients were eligible if they had unstable angina, non-ST-segment elevation myocardial infarction, or ST-segment elevation myocardial infarction, and underwent percutaneous coronary intervention. Enrolled patients were randomly assigned, via a web-based system by computer-generated block randomisation, to either the 6-month DAPT group or to the 12-month or longer DAPT group, with stratification by site, clinical presentation, and diabetes. Assessors were masked to treatment allocation. The primary endpoint was a composite of all-cause death, myocardial infarction, or stroke at 18 months after the index procedure in the intention-to-treat population. Secondary endpoints were the individual components of the primary endpoint; definite or probable stent thrombosis as defined by the Academic Research Consortium; and Bleeding Academic Research Consortium (BARC) type 2–5 bleeding at 18 months after the index procedure. The primary endpoint was also analysed per protocol. This trial is registered with ClinicalTrials.gov, number NCT01701453. Findings Between Sept 5, 2012, and Dec 31, 2015, we randomly assigned 2712 patients; 1357 to the 6-month DAPT group and 1355 to the 12-month or longer DAPT group. Clopidogrel was used as a P2Y12 inhibitor for DAPT in 1082 (79·7%) patients in the 6-month DAPT group and in 1109 (81·8%) patients in the 12-month or longer DAPT group. The primary endpoint occurred in 63 patients in the 6-month DAPT group and in 56 patients in the 12-month or longer DAPT group (cumulative event rate 4·7% vs 4·2%; absolute risk difference 0·5%; upper limit of one-sided 95% CI 1·8%; p non-inferiority =0·03 with a predefined non-inferiority margin of 2·0%). Although all-cause mortality did not differ significantly between the 6-month DAPT group and the 12-month or longer DAPT group (35 [2·6%] patients vs 39 [2·9%]; hazard ratio [HR] 0·90 [95% CI 0·57–1·42]; p=0·90) and neither did stroke (11 [0·8%] patients vs 12 [0·9%]; 0·92 [0·41–2·08]; p=0·84), myocardial infarction occurred more frequently in the 6-month DAPT group than in the 12-month or longer DAPT group (24 [1·8%] patients vs ten [0·8%]; 2·41 [1·15–5·05]; p=0·02). 15 (1·1%) patients had stent thrombosis in the 6-month DAPT group compared with ten (0·7%) in the 12-month or longer DAPT group (HR 1·50 [95% CI 0·68–3·35]; p=0·32). The rate of BARC type 2–5 bleeding was 2·7% (35 patients) in the 6-month DAPT group and 3·9% (51 patients) in the 12-month or longer DAPT group (HR 0·69 [95% CI 0·45–1·05]; p=0·09). Results from the per-protocol analysis were similar to those from the intention-to-treat analysis. Interpretation The increased risk of myocardial infarction with 6-month DAPT and the wide non-inferiority margin prevent us from concluding that short-term DAPT is safe in patients with acute coronary syndrome undergoing percutaneous coronary intervention with current-generation DES. Prolonged DAPT in patients with acute coronary syndrome without excessive risk of bleeding should remain the standard of care. Funding Abbott Vascular Korea, Medtronic Vascular Korea, Biosensors Inc, and Dong-A ST.

The Endeavor Resolute® (ER) is a zotarolimus-eluting stent (ZES) with a biocompatible BioLinx polymer. This study prospectively compared the clinical outcomes of 2 versions of ZES, ER and Endeavor Sprint® (ES), in patients with multivessel disease. A total of 488 patients who underwent multivessel percutaneous coronary intervention (PCI) were divided into 2 groups the ER group (n=288) and the ES group (n=200). The primary endpoint was a composite of major adverse cardiac events (MACE) consisting of death, myocardial infarction, and target vessel revascularization after 12 months. In all patients, the prevalence of diabetes was higher in the ER group (42.7% vs. 31.0%, p=0.009). The rate of post-PCI Thrombolysis in Myocardial Infarction flow grade 3 was higher in the ER group (100.0% vs. 98.0%, p=0.028). There were no between-group differences in the in-hospital, 1-month and 12-month clinical outcomes. In the propensity score matched cohort (n=200 in each group), no differences were observed in the baseline and procedural characteristics. There were no statistical differences in the rates of in-hospital, 1-month and 12-month events (12-month MACE in the ER and ES groups: 6.0% vs. 3.5%, p=0.240, respectively). The safety and efficacy of both versions of ZES were comparable in patients with multivessel disease during a 12-month clinical follow-up.