This study is designed to demonstrate that the onset of the antiplatelet effect of 90mg bid dose ticagrelor is more rapid and greater than 75 mg qd dose clopidogrel in patients undergoing CABG surgery.

Patients undergoing coronary artery surgery routinely receive aspirin therapy, as a standard treatment for preserving bypass graft patency. Although the dual antiplatelet therapy post CABG has not been recommended by guideline, present studies indicated the patients could benefit from the dual anti-platelet therapy. Using clopidogrel+aspirin could significantly reduce the early saphenous vein graft occlusion. . Many surgeons empirically prescribe dual anti-platelet therapy in spite of the indeterminacy of the clinical effects. ticagrelor is a novel, reversibly binding, oral, direct-acting P2Y12-receptor antagonist. The ONSET/OFFSET Study also shows that ticagrelor achieved much rapid and greater platelet inhibition than high-loading-dose clopidogrel in patients with stable CAD. ticagrelor is a novel, reversibly binding, oral, direct-acting P2Y12-receptor antagonist. The ONSET/OFFSET Study also shows that ticagrelor achieved much rapid and greater platelet inhibition than high-loading-dose clopidogrel in patients with stable CAD.

Inclusion Criteria:

• Female and/or male and ≥ 18 and <80 years of age
• Isolated CABG for the first time
• either on- or off- pump

Exclusion Criteria:

• Combined valvular surgery.
• A second surgery.
• Emergency surgery (a selective operation which change to emergency surgery in some special medical condition).
• Serum creatinine>130μmol/L.
• Oral clopidogrel therapy stops less than 5 days before the surgery.
• Oral anti-coagulation therapy (warfarin) that cannot be withheld.
• History of gastrointestinal or vaginal bleeding, Active pathological bleeding (e.g. active gastroduodenal ulcer or cerebral haemorrhage), history of postoperative gastrointestinal bleeding.
• Uric acid nephropathy, history of postoperative gastrointestinal bleeding.
• History of cerebral haemorrhage.
• Any other condition that may influence platelet count and function.
• Postoperative chest drainage > 200 ml/hr for two hours and more, re-operation for bleeding with persistent cardiac tamponade.
• Treated with IABP or ECMO after operation.
• Any other condition that may put the patient at risk (e.g., recurrent ventricular arrhythmias, peri-operative myocardial infarction, cancer).
• Contraindication to aspirin, clopidogrel and ticagrelor or other reason that study drug should not be administered (e.g., hypersensitivity, moderate or severe liver disease).
• Previous enrollment in other investigational drug or device study within 30 days.

Being or planning to pregnant.