Ticagrelor With Low-dose Versus Regular Aspirin in Patients With Acute Coronary Syndrome (ACS) at High-Risk for Ischemia After Percutaneous Coronary Intervention

Inclusion Criteria: * ACS patients at high risk for ischemic events after successful PCI with implantation of at least one drug eluting stent * Able and willing to provide informed consent and participate in 12 months follow-up period * Able to receive DAPT treatment * Enrollment into the study will require meeting at least one angiographic or clinical inclusion and none of the exclusion criteria. Clinical inclusion criteria: 1. Family history of premature coronary heart disease (Coronary heart disease in first-degree male relative \<55 years old or in first-degree female relative \<65 years old) 2. Repeated myocardial infarction 3. Positive serum cardiac troponin I/T 4. Combined with at least one organ/system with atherosclerotic disease (e.g. intracranial or peripheral arteries) 5. Type 2 diabetes mellitus under medication 6. Chronic kidney disease (eGFR\<60 mL/min/1.73 m2 or CrCl\<60ml/min) Angiographic Inclusion Criteria: 1. LM lesion requiring stents 2. Proximal LAD lesion(s) requiring stents 3. Bypass grafts lesion(s) requiring stents 4. Overall stent length ≥60 mm 5. History of in-stent thrombosis 6. Bifurcation lesions requiring at least 2 stents 7. Over two vessels lesions requiring stents 8. Calcified target lesion(s) requiring atherectomy 9. The intraoperative occurrence of no-reflow or slow-flow 10. Compressed branch vessels with a diameter of at least 2.0 mm failing to reach flow restoration (at least TIMI 3) Exclusion Criteria: * Need for chronic oral anticoagulation * With cardiomyopathy（HCM/DCM/RCM） * With severe ventricular arrhythmia requiring ICD implantation * With chronic respiratory disease (COPD, asthma, chronic bronchitis, pulmonary heart disease) * With severe infectious disease（active hepatitis B, active hepatitis C, AIDS） * With hematological disorders（thrombocytopenia, severe anemia, leukaemia） * With severe liver disease or kidney failure * With malignant tumor * With cognitive impairment * Unable or unwilling to provide informed consent or undergo follow-up