Thirty days clinical outcomes following stent implantation with aspirin-free prasugrel monotherapy in non-ST segment elevation myocardial infarction. Interim report from ASET-Japan pilot study

Abstract Background Dual antiplatelet therapy with a P2Y12 inhibitor, in addition to aspirin, is the standard therapy after percutaneous coronary intervention (PCI) for non-ST-segment elevation acute coronary syndrome (NSTE-ACS) to prevent ischemic cardiovascular events. The Acetyl-Salicylic Elimination Trial (ASET) pilot studies conducted in Japan in patients with NSTE-ACS investigated the safety and feasibility of a low-dose prasugrel monotherapy after PCI. Purpose To ensure the safety of the patients, enrolment in the study was implemented only after confirmation of a successful procedure. The abstract reports our interim analysis, aimed at evaluating preliminary safety and feasibility. Methods The ASET-Japan pilot study was designed to explore the feasibility and safety of a low dose of prasugrel monotherapy (3.75mg/day), without adjunctive aspirin, after optimal PCI using Everolimus eluting stent (EES) in Japanese patients with non-ST-segment elevation acute coronary syndromes. The primary endpoint in the ASET-Japan NSTE-ACS (Phase 2) is a 12-month clinical outcome. The study is currently in the follow-up phase. All the target lesions were treated with a platinum-chromium everolimus-eluting stent. The primary ischemic endpoint was the composite of cardiac death, spontaneous target vessel myocardial infarction, or definite stent thrombosis, and the primary bleeding endpoint was Bleeding Academic Research Consortium types 3 and 5 bleeding up to 12-month. If more than 3 events occurred, trial enrollment would have to be terminated by the data and safety monitoring board. Results One hundred one patients were enrolled after successful index PCI and completed a 30 days follow-up. The mean age was 69.1±12.3 years and 75.2% was male. The mean anatomical SYNTAX score was 7.9±4.7. Unstable angina (UAP) and NSTEMI were seen in 24.8% (25/101) and 75.2% (75/101) patients, respectively. According to the Braunwald classification, 8 percent of the patients were categorised as Class IA UAP, 48% as Class IB, 20% as Class IIB, 4% as Class IIIA and 20% as Class IIIB. In NSTEMI patients, the median (IQR) pre-procedural troponin value (cardiac Troponin T or I) was 2.79 (1.12 – 22.27) times the Upper Limit of Normal. According to the PRECISE DAPT score, 36.6% of patients were categorised as High Bleeding Risk (HBR) with scores above 25. At one month, the primary ischemic endpoints of cardiac death, target-vessel spontaneous MI or definite Stent thrombosis did not occur. Two patients (2.0%) had BARC type 3a bleeding. Conclusion Prasugrel monotherapy in the first 30 days following platinum-chromium everolimus-eluting stent deployment is a feasible and safe strategy in NSTE-ACS patients with simple anatomy and successful PCI.