Trimetazidine is a metabolic agent without any negative inotropic or vasodilatory properties. In addition, previous reports showed that trimetazidine was effective in reducing intracoronary platelet aggregation and preventing platelet thrombogenesis. Therefore, for the evaluation of these combination effects of statin and trimetazidine on patients with aspirin monotherapy who had previously received CABG and were free of the major adverse cardiac events such as death, MI, TLR, or TVR for 12 months, the investigators hypothesize that atorvastatin 40mg/day would be more effective in the prevention of the further late adverse cardiac and cerebrovascular events than other statin. To test this hypothesis, the investigators will perform a multi-center, randomized, prospective trial aimed at demonstrating the superiority of combination of high dose atorvastatin therapy and trimetazidine to pravastatin in patients with aspirin monotherapy 12 months after CABG surgery in real world practice.

Inclusion Criteria:

• Patients who had previously received CABG 12 months ago
• Patients who were free of death, MI or repeat revascularization within first 12 months after CABG
• Patients with mono antiplatelet therapy with aspirin alone
• Age of 20 years or older
• Patients with signed informed consent

Exclusion Criteria:

• History of DES or BMS implantation within 12 months
• Patients who required the continuing dual antiplatelet therapy or additional other types of antithrombotics or antiplatelets such as cilostazol or ticlopidine, etc besides aspirin after DES implantation
• Patients who could not be prescribed aspirin or statins due to contraindication or severe side effects
• Pregnant women or women with potential childbearing
• Life expectancy ≤ 2 year