Study Purpose Coronary heart disease (CAD) is a leading global cause of death, with Acute Coronary Syndrome (ACS) as its acute and life-threatening subtype. Percutaneous Coronary Intervention (PCI) plus stent implantation is the first-line treatment for ACS, and post-PCI Dual Antiplatelet Therapy (DAPT, aspirin + P2Y₁₂ inhibitor) is core for thrombosis prevention but increases bleeding risk. Approximately 40% of ACS patients are classified as High Bleeding Risk (HBR). China lacks a unified DAPT quality control system, and the predictive value of the OPT-CAD ischemic risk score for this population remains unvalidated. This study aims to: 1) Evaluate the feasibility and influencing factors of the DAPT quality control system in HBR ACS patients post-PCI; 2) Verify the accuracy of the OPT-CAD score in predicting ischemic risk, providing evidence for personalized treatment.

Eligibility Criteria Inclusion Criteria Aged ≥18 years; Diagnosed with ACS and implanted with at least one drug-eluting stent (DES) during PCI; Meets ARC-HBR (Academic Research Consortium for High Bleeding Risk) HBR definition (1 major criterion or 2 minor criteria); Able to complete OPT-CAD scoring; Tolerates 12-month DAPT (physician assessment); Signs informed consent. Exclusion Criteria Allergy to aspirin, clopidogrel, ticagrelor, or other study-related antiplatelet drugs; Severe ischemia or major bleeding during current hospitalization; Terminal illness with life expectancy <1 year; Pregnant or planning pregnancy within 1 year; Enrolled in other ongoing clinical studies. Study Process

This is a multi-center prospective cohort study (we will follow eligible patients over 12 months to collect real-world data without changing their standard care) recruiting 3,500 participants nationwide. Post-enrollment:

Receive 6-12 months of standard DAPT (regimen determined by your physician); Follow-ups at 1 month (±7 days), 3 months (±14 days), 6 months (±30 days), and 12 months (±30 days) post-PCI (via phone or outpatient visit) to collect medication adherence, bleeding/ischemic events, and clinical outcomes; Confidential data collection via a secure Electronic Data Capture (EDC) system. Study Endpoints Primary Endpoints Feasibility of the DAPT quality control system, inter-hospital differences in DAPT use, 6-12 month DAPT completion rate, and impact of DAPT interruption on patient outcomes; Accuracy of the OPT-CAD score in predicting ischemic risk for HBR patients. Secondary Endpoints 12-month bleeding event rates (BARC 1-5 types, including minor bleeding like puncture site bleeding and major bleeding like intracranial hemorrhage); 12-month ischemic event rates (including target lesion failure-cardiac death, target vessel-related myocardial infarction, or target lesion revascularization-all-cause death, ischemic stroke, definite stent thrombosis, etc.); DAPT interruption rate, P2Y₁₂ inhibitor discontinuation rate (≥1 week), and aspirin discontinuation rate (≥1 week).

Key Information for Participants Voluntary participation: You may withdraw anytime without penalty or loss of medical benefits; Confidential data protection: Personal information will be anonymized with a unique study ID; Free study-related assessments and follow-ups; Prompt medical care will be provided for any adverse events. For inquiries, contact the study team at the participating hospital.

This study is a prospective, multicenter, observational registry cohort study designed to evaluate real-world dual antiplatelet therapy (DAPT) management in high-bleeding-risk patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

Eligible patients undergoing PCI will be screened against the study inclusion and exclusion criteria. Patients who meet eligibility requirements will be invited to participate, provide informed consent, and be assigned a unique study identification number. Study participation will not alter routine clinical care, and all treatment decisions, including DAPT regimen selection and duration, will be determined by the treating physician in accordance with standard clinical practice.

A total of approximately 3,500 evaluable patients are planned to be enrolled across multiple centers nationwide, including prefecture-level/district/county hospitals and provincial or national key hospitals. Enrollment will reflect real-world clinical practice, with no more than a predefined proportion of patients enrolled at any single site.

Clinical data will be collected prospectively at baseline and during routine follow-up at approximately 1, 3, 6, and 12 months following PCI. Collected information will include patient characteristics, PCI-related data, DAPT treatment patterns, and clinical outcomes.

The registry is designed to characterize real-world application of a DAPT quality control indicator system and to evaluate the prognostic performance of the OPT-CAD score in high-bleeding-risk ACS patients. Findings from this study are expected to provide real-world evidence to support standardized DAPT quality control and personalized antiplatelet therapy in this high-risk population.

Inclusion Criteria:

• Aged ≥ 18 years
• Clinically diagnosed with ACS and received implantation of at least one drug-eluting stent (DES)
• Meets 1 major criterion or 2 minor criteria of the ARC-HBR high-bleeding-risk definition
• Able to complete the OPT-CAD score calculation
• Judged by the investigator to tolerate DAPT for at least 12 months
• Signed the informed consent form

Exclusion Criteria:

• Allergy to study medications such as aspirin, clopidogrel, or ticagrelor
• Occurrence of major ischemic or bleeding events during the current hospitalization
• Presence of other severe diseases with a life expectancy of less than one year
• Pregnancy, or women of childbearing potential who plan to become pregnant within one year
• Current participation in another clinical study and still within its observation period.

Study participants will be selected from inpatients admitted to multiple nationwide medical centers (including prefecture/county-level hospitals and provincial/national key hospitals) who are clinically diagnosed with Acute Coronary Syndrome (ACS) and undergo Percutaneous Coronary Intervention (PCI) with Drug-Eluting Stent (DES) implantation during hospitalization. The source population consists of ACS patients who meet the clinical diagnostic criteria, require PCI treatment, and are potentially at high bleeding risk (may fulfill ARC-HBR criteria). Patients with clear contraindications to Dual Antiplatelet Therapy (DAPT), inability to complete follow-up, or other conditions that make them unsuitable for the study are excluded from the source population.