Antiplatelet Effects of Ticagrelor Versus Clopidogrel in American Indian Patients

Inclusion Criteria: * Documented stable CAD fulfilling any of the following, and taking 81mg ASA daily treatment: * Females must be post menopausal for at least one year or surgically sterile for at least 6 months and negative urine pregnancy test * Self-identified as American Indian * Genetic Inclusion Criteria: must sign the informed consent for genetic and biological sample banking. Exclusion Criteria: * Any indication for oral anticoagulant or dual antiplatelet treatment * Concomitant therapy with strong CYP3A inhibitors, CYP3A substrates with narrow therapeutic index, or strong CYP3A inducers within 14 days and during study treatment and during: * Increased bleeding risk including: * Diabetic patients with HbAlC \> 10% at screening * Contraindication to clopidogrel, ASA, or ticagrelor - A history of alcohol and/or substance abuse that could interfere with conduct of the trial * Patients requiring dialysis * Patients scheduled for revascularization (e.g., PCI, CABG) during the study period * Any acute or chronic unstable condition in the past 30 days * Known active or recurrent hepatic disorder * Patients who had ACS or stent placed within 12 months of screening * History of Uric Acid nephropathy