Competitive studies were conducted at the same time, and enrollment was suspended.

To determine the safety and efficacy of Ticagrelor versus Clopidogrel for the reduction of adverse cardiovascular outcomes in patients with high platelet reactivity on clopidogrel after successful implantation of coronary drug-eluting stents.

This is a multi-center, randomized, single-blind, investigator-initiated study with a parallel design. Patients with coronary artery disease undergoing percutaneous coronary intervention and presenting high platelet reactivity on clopidogrel as assessed with the PL-11 analyzer (platelet maximum aggregation ratio [MAR%] ≥ 55 %) at 2 hours post-clopidogrel 300mg LD (Day 0), will be randomized after informed consent, in a 1:1 ratio to the following treatment groups:

Group Α: Ticagrelor 180 mg immediate loading (on Day 0) followed by 180mg/day starting from Day 1 until Day 365 (12 months after randomization).

Group Β: Clopidogrel 150mg per day, starting from Day 1 until Day 365 (12 months after randomization).

Platelet reactivity assessment will be performed before randomization (Day 0), and 3-day after randomization (Day 3). Documentation of major adverse cardiac and cerebrovascular events (death, myocardial infarction, stent thrombosis, stroke, revascularization procedure with PCI or CABG) and serious adverse events (bleeding, other adverse events) will be performed until 12 months.

Inclusion Criteria:

• Patients who agreed to the experimental plan which was permitted by IRB;
• Patients planned to take dual antiplatelet therapy for 12 months.

Exclusion Criteria:

• Severe hepatic dysfunction defined as serum transaminase > 3 times normal limit;
• Renal dysfunction defined as eGFR < 30ml/min/1.73m^2;
• Co-morbidity with an estimated life expectancy of < 50 % at 12 months;
• Scheduled surgery in the next 12 months, which resulted protocol changes;
• Known allergy against study drug or device;
• Use of glycoprotein IIb/IIIa inhibitor during the perioperative period;
• Anticoagulation treatment including warfarin.