Inclusion Criteria:

• Males or females aged 18 years or older.
• 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.
• Indication for the procedure may be stable angina (angina without a change in frequency or pattern for the 6 weeks before the procedure) or ischemia (ischemic findings on a stress test, i.e., stress EKG, stress ECHO, stress myocardial perfusion imaging), unstable angina without ST changes, or NSTE-ACS (unstable angina with ST changes, non-ST elevation MI).
• 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.
• A female patient is eligible to enter the study if she is (1) 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.
• History of gastro-intestinal bleeding within 6 months.
• 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.
• Planned elective cardiac or non-cardiac surgery within 6 months.
• Current or planned therapy with coumadin anticoagulation.
• Current or planned therapy with other thienopyridine class of ADP receptor inhibitors (e.g., prasugrel)
• Severe allergy to stainless steel, contrast dye, unfractionated heparin, low molecular weight heparin, 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.
• Pre-procedure ("upstream") GPIIb/IIIa use (within 30 days for abciximab, or 5 days for tirofiban or eptifibitde),
• Planned peri-procedural GPIIb/IIIa use.
• 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 prior to randomization and those whom require a target vessel revascularization 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