Evaluation of Antiplatelet Effects and Safety of Intraoperative Administration of Ticagrelor Versus Clopidogrel

Inclusion Criteria: 1. Provision of informed consent prior to any study specific procedures 2. A patient who is considered as ethnic Chinese 3. 80years \>aged\> 18years, male or female 4. Patient is willing to perform HCR with the following conditions: Multi-vessel coronary artery disease with unfavorable left anterior descending coronary artery (LAD) for percutaneous coronary intervetion (PCI) (i.e., chronic total occlusion, excessive tortuosity, severely diffuse lesion), unprotected left main coronary artery disease, and non-LAD lesions were technically feasible for PCI with a drug-eluting stent (DES) .Limitations to traditional coronary artery bypass graft (CABG), such as pre-existing organ dysfunction, heavily calcified proximal aorta, or lack of suitable graft conduits Exclusion Criteria: 1. Involvement in the planning and/or conduct of the study 2. Previous enrolment or randomization in the present study 3. Participation in another clinical study with an investigational product during the last 30 days 4. Contraindication or other reason that clopidogrel or ticagrelor should not be administered (eg, hypersensitivity, active bleeding, moderate or severe liver disease, history of previous intracranial bleed, GI bleed within the past 6 months, major surgery within 30 days) 5. With coagulation disorder 6. With uric acid nephropathy 7. History of intolerance or allergy to acetylsalicylic acid (ASA) or clopidogrel or ticagrelor 8. Patient has a coronary artery bypass graft (CABG) history. 9. left subclavian artery and LIMA stenosis 10. buried intramyocardial LAD 11. need for a concomitant operation (e.g., valve repair or replacement) 12. overt congestive heart failure 13. Unsuccessful LIMA-LAD graft 14. hemodynamic instability 15. other conditions rendering PCI unsuitable (e.g., fresh thrombus, coronary vessel diameter \<1.5 mm) 16. Platelet count less than 100\*10\^9/L 17. Haemoglobin (Hb) level less than 110g/L 18. White blood cell count less than 4\*10\^12/L 19. Recent (within 30 days of dosing) blood donation 20. Fibrinolytic therapy in the 24 hours prior to randomisation, or planned fibrinolytic treatment following randomisation (eg, for ST-segment elevation myocardial infarction or pulmonary embolism) 21. P2Y12 receptor inhibitor therapy in 7 days before HCR surgery. 22. Nonselective non-steroidal anti-inflammatory drugs (NSAIDs) and prostacyclins (PGI2) therapy that cannot be stopped 23. Increased risk of bradycardic events (eg, no pacemaker and known sick sinus syndrome, second degree atrioventricular block, third degree atrioventricular block or previous documented syncope suspected to be due to bradycardia). 24. Concomitant oral or intravenous therapy (see examples below) with strong CYP3A inhibitors, CYP3A substrates with narrow therapeutic indices, or strong CYP3A inducers within 14 days of study treatment or cannot be stopped for the course of the study. Strong inhibitors: ketoconazole, itraconazole, voriconazole, telithromycin, clarithromycin, nefazadone, ritonavir, saquinavir, nelfinavir, indinavir, atanazavir, over 1 litre daily of grapefruit juice. Substrates with narrow therapeutic index: cyclosporine, quinidine. Strong inducers: rifampin/rifampicin, phenytoin, carbamazepine. The sponsor should be consulted for enrolment with any concomitant medicines which are suspected of undergoing strong drug-drug interaction 25. Any other condition which in the opinion of the investigator, may either put the patient at risk or influence the result of the study (e.g., cardiogenic shock or active cancer) 26. Moderate or severe renal disease; 27. Moderate or severe chronic lung disease or asthma; 28. Pregnancy or lactation