A Phase IV Study of the Onset and Maintenance of the Antiplatelet Effect of Ticagrelor Compared With Clopidogrel in Chinese Patients With ACS

Inclusion Criteria: * 1\. Provision of informed consent prior to any study specific procedures * 2\. Female or male aged at least 18 years * 3\. Females of child-bearing potential must have a negative urine pregnancy test at enrolment and be willing to use reliable contraception * 4\. Index event of non-ST or ST segment elevation ACS. Exclusion Criteria: * 1.Contraindication or other reason that clopidogrel or ticagrelor should not be administered (eg, hypersensitivity, active bleeding, moderate or severe liver disease, history of previous intracranial bleed, GI bleed within the past 6 months, major surgery within 30 days) * 2\. Oral anticoagulation therapy or GP IIb/IIIa receptor antagonists therapy within 30 days prior to randomisation or cannot be stopped * 3\. Ticagrelor or clopidogrel or other P2Y12 inhibitors within 14 days prior to randomisation * 4\. Requires dialysis * 5\. Nonselective non-steroidal anti-inflammatory drugs (NSAIDs) and prostacyclins (PGI2) therapy that cannot be stopped