Reduced-dose prasugrel monotherapy without aspirin after PCI with the SYNERGY stent in East Asian patients presenting with chronic coronary syndromes or non-ST-elevation acute coronary syndromes: rationale and design of the ASET Japan pilot study.

The Acetyl Salicylic Elimination Trial (ASET) Japan pilot study is a multicentre, single-arm, open-label, proof-of-concept study with a stopping rule based on the occurrence of definite stent thrombosis. This study aims to demonstrate the feasibility and safety of low-dose prasugrel monotherapy following percutaneous coronary intervention (PCI) in Japanese patients presenting with chronic coronary syndromes (CCS) or non-ST-elevation acute coronary syndromes (NSTE-ACS). Four hundred patients with a SYNTAX score <23 requiring PCI due to CCS or NSTE-ACS will be screened and considered eligible for the study. The enrolment is planned in two phases: 1) 200 patients presenting with CCS, followed by 2) 200 patients presenting with NSTE-ACS. After optimal PCI with implantation of a SYNERGY (Boston Scientific) stent, patients will be enrolled and loaded with prasugrel 20 mg, followed by a maintenance dose of prasugrel 3.75 mg once daily without aspirin continued for 3 months in Phase 1 (CCS patients), and for 12 months in Phase 2 (NSTE-ACS patients). After these follow-up periods, prasugrel will be replaced by standard antiplatelet therapy according to local practice. The primary endpoint is a composite of cardiac death, target vessel myocardial infarction, or definite stent thrombosis after the index procedure. The primary bleeding endpoint is any Bleeding Academic Research Consortium type 3 or 5 bleeding occurring within 3 months of the index PCI for CCS patients, or 12 months for NSTE-ACS patients. The ASET Japan study is designed to demonstrate the feasibility and safety of reduced-dose prasugrel monotherapy after PCI in East Asian patients with acute and chronic coronary syndromes.
Competing Interests: S. Masuda reports a grant from Terumo outside the submitted work. T. Muramatsu has received honoraria/speaker fees from Boston Scientific Japan and Daiichi Sankyo. K. Kozuma received honoraria for lectures and is a member of the advisory boards of Daiichi Sankyo and Boston Scientific. K. Tanabe received honoraria from Boston Scientific and Daiichi Sankyo. M. Nakamura reports grants from Daiichi Sankyo during the conduct of the study; and honoraria from Bayer KK, Daiichi Sankyo KK, and Japan Lifeline. Y. Morino received a scientific grant and lecture fee from Boston Scientific. P.W. Serruys reports institutional grants from Sino Medical Sciences Technology, SMT, Philips Volcano, Xeltis, and HeartFlow, outside the submitted work. The other authors have no conflicts of interest to declare.