Ticagrelor-based De-escalation of Dual Antiplatelet Therapy After Coronary Artery Bypass Grafting trial (TOP-CABG trial) is a multicenter, randomized, double-blind, non-inferiority, parallel controlled trial. The aim of TOP-CABG is to investigate whether de-escalated dual antiplatelet therapy (De-DAPT) is non-inferior to dual antiplatelet therapy (DAPT) in efficacy on inhibiting great saphenous vein (SVG) graft occlusion and is superior in reducing bleeding events in patients accepting coronary artery bypassing grafting.

After informed consent, at least 10 centers and 2,300 eligible admissions will be recruited. Eligible patients would be randomized (1:1) in double-blind manner (patients and treating physicians) to dual antiplatelet therapy (DAPT) group (ticagrelor 90mg bid and aspirin 100 mg qd for 12 month) and de-escalated DAPT (De-DAPT) group (90mg bid and aspirin 100 mg qd for first 3 months, and then aspirin 100 mg qd and placebo for 9 months).

Inclusion criteria

1. Patients 18-80 of age. 2. Patients undergo planned CABG for the first time with ≥1 SVGs 3. Patients with written informed consent. Exclusion criteria

1. Concomitant valve (excluding aortic bioprosthesis), aorta, or rhythm surgery during the same session.
2. Patients undergo emergency CABG.
3. Patients with single coronary artery disease.
4. Patients with cardiogenic shock and hemodynamic instability.
5. Patients with sick sinus syndrome, 2nd or 3rd atrioventricular block.
6. Patients with contraindications for coronary computed tomography angiography or coronary angiography (eg. contrast allergy).
7. Use of other antiplatelet drugs than aspirin or ticagrelor (clopidogrel, prasugrel, etc) and unable to discontinue this medication after CABG, in the treating physician's or the investigator's opinion.
8. Patients who take oral anticoagulants before CABG and have to use anticoagulants after surgery.
9. Contraindication for the use of ticagrelor or aspirin (ie. history of bleeding diathesis within 3 months prior presentation, severe gastrointestinal bleeding within 1year prior presentation, peptic ulcer without gastrointestinal bleeding in past 3 years or history of intracranial hemorrhage, allergy, severe gastrointestinal reaction caused by aspirin).
10. Placement of a drug-eluting stent in a coronary or cerebral artery within 6 months of CABG or placement of a bare-metal stent in a coronary or cerebral artery within 1 month of CABG
11. Thrombocytopenia before CABG (< 100 x 109/L).
12. patients with severe renal function impairment requiring dialysis or active liver disease, including patients with unexplained persistent elevated transaminase or any transaminase more than 3 times the normal limit.
13. Use of strong inhibitors of CYP3A4
14. Patients who have to use methotrexate and ibuprofen.
15. Patients with active malignant tumors with increase in bleeding risk in the investigator's opinion
16. Pregnant patients, patients who have given birth within the past 90 days, or who are breastfeeding.
17. Premenopausal women who do not take adequate contraception. Adequate contraception refers to the adoption of at least two reliable methods of contraception, one of which must be a barrier method of contraception.
18. CABG volume of the surgeon less than 50.