Early Single Antiplatelet Therapy After IVUS-Guided PCI in Acute Coronary Syndrome

This is a prospective, open-label, multicenter, randomized, phase IV clinical trial designed to evaluate the safety and efficacy of early aspirin discontinuation followed by potent P2Y12 inhibitor monotherapy after intravascular ultrasound (IVUS)-guided drug-eluting stent implantation in patients with acute coronary syndrome. A total of 1,900 patients who achieve complete revascularization after IVUS-guided percutaneous coronary intervention (PCI) and meet the predefined successful IVUS-guided PCI criteria will be randomized in a 1:1 ratio to either the early single antiplatelet therapy group (Early SAPT: ticagrelor or prasugrel monotherapy) or the standard dual antiplatelet therapy group (Standard DAPT: aspirin plus ticagrelor or prasugrel). Randomization will be performed within 96 hours after completion of PCI, and clinical follow-up will be conducted at 1 month, 3 months, 6 months, and 12 months after randomization. The primary endpoints are major adverse cardiovascular events, defined as a composite of all-cause death, myocardial infarction, ischemia-driven target vessel revascularization, and definite or probable stent thrombosis occurring up to 12 months after randomization, and clinically relevant bleeding, defined as Bleeding Academic Research Consortium (BARC) type 2, 3, or 5 bleeding occurring up to 12 months after randomization. This study aims to determine whether early P2Y12 inhibitor monotherapy is non-inferior to standard dual antiplatelet therapy (DAPT) for ischemic events and is superior in reducing clinically relevant bleeding.

Inclusion Criteria: 1. Age \>=18 years 2. Diagnosis of acute coronary syndrome, including ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), or unstable angina (UA) 3. Successful IVUS-guided PCI with drug-eluting stent implantation 4. Randomization within 96 hours after PCI 5. Written informed consent Exclusion Criteria: 1. Planned staged PCI or CABG 2. PCI failure, including no-reflow, major dissection, or thrombosis 3. Need for oral anticoagulation 4. Major bleeding within 30 days 5. History of hemorrhagic stroke or ischemic stroke within 6 months 6. Platelet count \