Inclusion Criteria:

1. Patient less than 18 years of age
2. Patient referred as an outpatient for elective cardiac catheterization with coronary angiography and ad hoc percutaneous coronary intervention (if coronary anatomy suitable)
3. Patient has stable angina or a stress test suggestive of ischemia and/or prior myocardial infarction
4. Anticipated femoral arterial approach for the cardiac catheterization procedure
5. Patient provides written informed consent

Exclusion Criteria:

Patients will be excluded if any of the following are present:

1. Use of clopidogrel or ticlopidine during the 14 days prior to the scheduled procedure
2. Known hypersensitivity to clopidogrel (regardless of desensitization) or to any other components of Plavix

3. Contraindication to clopidogrel, including

   1. Pre-existing bleeding disorder or hematological dyscrasia
   2. INR >1.4 immediately prior to the scheduled procedure
   3. Platelet count <50 K/uL
   4. Significant bleeding during the 14 days prior to the scheduled procedure
   5. Surgery or invasive procedure at a non-compressible location during the 30 days prior to the scheduled procedure
   6. Anticipated need for surgery or other invasive procedure within 30 days following the scheduled procedure
   7. Patient states unwillingness to undergo transfusion of red blood cells even in the event of life threatening bleeding

4. Unstable cardiac status

   1. Patient was admitted for a cardiac condition and referred as an inpatient for cardiac catheterization
   2. Myocardial infarction diagnosed as occurring during the 30 days prior to the scheduled procedure
   3. Pre-procedure troponin-T >0.01 ng/mL
   4. Unstable angina

   i. Ischemic symptoms at rest ii. Ischemic symptoms with mild exertion (e.g., walking one to two level blocks or climbing one flight of stairs) e. Pre-procedure electrocardiogram with ST segment changes indicative of ongoing myocardial injury or ischemia

5. Chronic renal failure (which may raise troponin-T levels)

   1. Patient currently undergoing dialysis
   2. Serum creatinine >2 mg/dL
   3. Estimated glomerular filtratation rate (eGFR using the MDRD formula) <45 mL/min/1.73 m2

6. Procedural factors

   1. Patient does not require coronary angiography as part of the scheduled cardiac catheterization
   2. Patient is not a candidate for percutaneous coronary intervention during the same procedure as the diagnostic coronary angiography
   3. Anticipated need for arterial access using brachial, radial or other non-femoral approach
   4. Anticipated need to access the femoral artery via a femoral bypass graft
   5. Anticipated need for an arterial sheath 6 French in size or larger (e.g., planned evaluation of aortic stenosis or hypertrophic cardiomyopathy)
   6. Anticipated need for heparin anticoagulation during the diagnostic cardiac catheterization procedure (e.g., crossing a stenosed aortic valve with a 0.035" wire, planned intra-vascular ultrasound or pressure wire study)
7. Woman of child-bearing potential who does not have a negative pregnancy test immediately prior to the scheduled procedure
8. Participation in another non-observational clinical study that has not yet completed all mandatory follow-up (i.e., patients who are participating in a "natural history" observational registry where no active therapy is being investigated may participate)
9. Prior participation in this study
10. Inability to provide written informed consent or demonstrate understanding of the risks and benefits associated with participation in this study