Loading Dose Arm for Coronary Artery Disease (PPD Trial)

* The purpose of this study is to determine the level of inhibition of platelet activation of an approved thienopyridine(clopidogrel or prasugrel) and aspirin regimen in the setting of drug eluting coronary stent implantation. * In subjects with high residual levels of platelet reactivity after receiving either a maintenance or loading dose of either clopidogrel or prasugrel, a cross over of thienopyridine treatment to the alternate medication will occur. * The study tests the hypothesis that adequate platelet inhibition will occur in subjects who have high levels of platelet reactivity and are subsequently switched from clopidogrel to prasugrel(loading or maintenance dose) without increased episodes of bleeding or MACE events at discharge and 30 days post Percutaneous Coronary Intervention (PCI).