GRAVITAS: Gauging Responsiveness With A VerifyNow Assay-Impact On Thrombosis And Safety

Inclusion Criteria: * Males or females aged 18 years or older. * 2\. Patients undergoing coronary angiography and possible PCI with planned use of at least one drug-eluting stent (DES), and without planned use of glycoprotein IIb/IIIa inhibitors. One or more bare metal stents (BMS) may be implanted, and other lesions may be treated without stenting, as long as at least one DES is implanted. However, the procedure must be successful and uncomplicated for all lesions (DES + BMS + non stent). * Indication for the procedure may be stable angina or ischemia, unstable angina, non-ST elevation MI (NSTEMI), or ST elevation MI (STEMI). * Have the ability to understand the requirements of the study, including consent for use and disclosure of research-related health information. * Have the ability to comply with study procedures and protocol, including required study visits. * 6\. A female patient is eligible to enter the study if she is (1) of child-bearing potential and not pregnant or nursing; (2) not of child-bearing potential (i.e., has had a hysterectomy, have both ovaries removed, has tubal ligation, or are post-menopausal, defined as 24 months without menses). Exclusion Criteria: Pre-PCI * PCI within previous 30 days. * Prior consent to participate in GRAVITAS and not randomized by IVRS. * History of gastro-intestinal bleeding within 6 months. * Major non-cardiac surgery within 6 weeks. * Ischemic stroke within 6 weeks. * Any history of hemorrhagic stroke or sub-arachnoid hemorrhage. * Other bleeding diathesis, or considered by investigator to be at high-risk for bleeding on long-term clopidogrel therapy. * Minor surgical procedures that require cessation of dual anti platelet therapy and result in significant bleeding are NOT eligible. * Current or planned therapy with coumadin anticoagulation. * Current or planned therapy with other thienopyridine class of ADP receptor inhibitors (e.g., prasugrel, ticlopidine), or the non-thienopyridine ticagrelor. * Severe allergy to stainless steel, contrast dye, unfractionated heparin, low molecular weight heparin, or bivalirudin that cannot be adequately pre-medicated. * Allergy to aspirin or clopidogrel. * Current enrollment in an investigational drug or device study that has not reached the time period of the primary endpoint. * Have received GPIIb/IIIa inhibitors eptifibatide or tirofiban within 24 hours before or during PCI or abciximab within 10 days before or during PCI. * Thrombocytopenia (defined as platelet count \< 100 K). * Anemia (hematocrit \< 30%). * Polycythemia (hematocrit \> 52%). * Patients unwilling or unable to complete clinical follow-up for the duration of the study. Exclusion Criteria: Post-PCI * PCI with placement of at least one DES is not performed. * Planned staged PCI in the next 6 months post-procedure. * Unsuccessful PCI (post-procedure diameter stenosis \>30% with less than TIMI-3 flow in any treated vessel). * Patients with in-hospital STEMI confirmed by ECG prior to randomization or those whom require a target vessel revascularization of the index lesion prior to randomization. * Patients with acute stent thrombosis before Accumetrics VerifyNow tests. * Administration of any GPIIb/IIIa during PCI procedure or prior to initial hospital discharge. * Failure to meet clopidogrel requirements * Major complication during or after PCI