A Clinical Trial to Demonstrate the Efficacy of Cangrelor

INCLUSION CRITERIA To be included in this study, subjects must meet the following criteria: * Angiography demonstrating atherosclerosis amenable to treatment by percutaneous coronary intervention (PCI) with or without stent implantation and diagnosis of Acute Coronary Syndrome (ACS) by elevated cardiac markers or ischemic chest discomfort w/electrocardiogram changes + age \> 65 or diabetes or ST-elevation MI. EXCLUSION CRITERIA Subjects will be excluded from the study if they present with any of the following: 1. Not a candidate for PCI 2. Increased bleeding risk: ischemic stroke within the last year or any previous hemorrhagic stroke, tumor, cerebral arteriovenous malformation, or intracranial aneurysm; recent (\<1 month) trauma or major surgery (including by-pass surgery); currently receiving warfarin, active bleeding 3. Impaired hemostasis: known International Normalized Ratio (INR) \>1.5 at screening; past or present bleeding disorder (including congenital bleeding disorders such as von Willebrand's disease or hemophilia, acquired bleeding disorders, and unexplained clinically significant bleeding disorders), thrombocytopenia (platelet count \<100,000/µL), or history of thrombocytopenia or neutropenia associated with clopidogrel 4. Severe hypertension not adequately controlled by antihypertensive therapy at the time of randomization 5. Receipt of fibrinolytic therapy in the 12 hours preceding randomization 6. Receipt of clopidogrel dose exceeding maintenance dose (ie, \>75 mg) at any time in the 5 days preceding randomization 7. Inability to swallow study capsules 8. Glycoprotein IIb/IIIa (GPI) Inhibitor usage within the previous 12 hours \[applicable to unstable angina (UA) and non-ST-elevation myocardial infarction (NSTEMI) patients\] Subjects excluded for any of the above reasons may be re-screened for participation at any time if the exclusion characteristic has changed.