The objective is to describe and quantify levels of platelet reactivity in three different cohorts of patients taking thienopyridine: patients who report nuisance bleeding, patients who report alarming bleeding, and patients who report no nuisance or alarming bleeding. The investigators hypothesize that patients with nuisance or alarming bleeding events on maintenance thienopyridine therapy will have lower levels of platelet reactivity than patients without nuisance or alarming bleeding on thienopyridine therapy.

Inclusion Criteria:

• Patients 18 years or older from both genders
• Underwent PCI within the last year
• Taking maintenance dose of clopidogrel 75 mg once a day or prasugrel 10 mg once a day for at least five 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 anemia, thrombocytopenia, bleeding disorder, or currently active bleeding
• On warfarin therapy at the time of blood draw
• Known blood transfusion within the preceding 10 days of the blood draw
• Patients treated with non-steroidal anti-inflammatory drugs (NSAIDS, not to include aspirin) within the previous 5 days
• Any significant medical condition that, in the investigator's opinion, may interfere with the patient's optimal participation in the study.

Patients who have undergone PCI and have reported no bleeding, nuisance bleeding or alarming bleeding.