Platelet Function Monitoring in Patients With Acute Myocardial Infarction

Inclusion Criteria: * Patient \>18 years old. * Patient scheduled to undergo PCI for either stable CAD or AMI: * Stable CAD defined as negative cardiac isoenzymes prior to the PCI as well as no resting ECG changes indicative of ACS. * AMI defined as positive cardiac isoenzymes prior to the PCI and/or resting ECG changes indicative of ACS. 3\. Patients treated with a loading dose of clopidogrel at least 6 hours prior to the blood draw or on a maintenance dose of clopidogrel (of at least 75mg QD) for a minimum of 5 days. Exclusion Criteria: * Known allergies to aspirin, clopidogrel, or prasugrel * Use of a glycoprotein (GP) IIb/IIIa inhibitor within 8 hours of the blood draw; * Patient known to be pregnant or lactating; * Patient with known history of bleeding diathesis or currently active bleeding; * Platelet count \<100,000/mm the day of the blood draw; * Hematocrit \<25% the day of the blood draw; * On warfarin therapy at the time of the blood draw or the need for warfarin therapy in the subsequent month following the blood draw; * Known blood transfusion within the preceding 10 days of the blood draw; * Patient who has received NSAID (not including ASA) within preceding 24 hours of the blood draw; * Patients presenting with cardiogenic shock; * Any significant medical condition, which in the investigator's opinion may interfere with the patient's optimal participation in the study.