 Effects of dual antiplatelet therapy with aspirin and clopidogrel after percutaneous coronary intervention has been proven. However, patients with low response to those agents are reported be associated with adverse clinical outcomes. We suppose that optimized antiplatelet therapy for individual patients based on platelet function assay may improve long-term outcomes especially in patients with high risk of thrombosis. In this prospective randomized study, patients in control group all receive standard dual antiplatelet therapy, and patients in optimized group receive different antiplatelet therapy according to risk stratification. 