 - There will be two treatment groups; one will receive clopidogrel 75 mg 1 tablet qd, the second matching placebo of clopidogrel 1 tablet qd. These study drugs will be administered on top of low-dose aspirin 75-162 mg qd systematically prescribed to such patients. In addition, patients enrolled in CHARISMA will be managed as appropriate for their risk factors for atherosclerosis: eg. high blood pressure, high cholesterol, diabetes...etc. 