The purpose of this study is to compare Low-Dose, Standard-Dose Ticagrelor and Clopidogrel for Inhibition of Platelet Reactivity in Patients with Acute Coronary Syndromes

Inclusion Criteria:

• ST elevation or non ST elevation acute coronary syndrome patients of chest pain within 24 hours

Exclusion Criteria:

• Known hypersensitivity to clopidogrel and ticagrelor and aspirin
• Treatment with anticoagulants
• Exposure to a thrombolytic agent within 24 hours prior to randomization
• Use of glycoprotein IIb - IIIa inhibitors at randomization
• History of major hemorrhage (intracranial, gastrointestinal, etc.)
• clotting disorder and/or bleeding disorder
• Any history of Severe renal or hepatic dysfunction
• Hematologic disorder including a Hemoglobin less than 10 g/L or a platelet count less than 80,000 cells/mm3
• Cardiac shock, severe left ventricular dysfunction LVEF less than 30%
• Sick sinus syndrome or second degree of av block without permanent pacemaker
• No concurrent cytochrome p450 3a inhibitors and enhancers within 2 weeks
• Subject has any condition for which, in the opinion of the investigator, participation would not be in the best interest of the subject (eg,drug and alcohol abuse, mental illness) or that could prevent, limit, or confound the protocol-specified assessments.
• Life expectancy of less than 6 months
• Pregnancy or lactating
• Participation in any drug study in the previous 3 months
• Inability to follow the protocol and comply with follow-up requirements or any other reason that the investigator feels would place the patient at increased risk