Comparison of Ticagrelor Versus Clopidogrel on Residual Thrombus Burden During PCI: an OCT Study

Inclusion Criteria: Patient Characteristics: 1. Males and non-pregnant females \> 18 and \< 79 years of age presenting with acute coronary syndrome defined as having two of the following criteria: 1. Signs and symptoms consistent with accelerated angina or prolonged angina (lasting greater than 20 minutes) either at rest or with minimal exertion 2. ECG changes indicative of new ischemia 3. Levels of cardiac biomarkers (troponin-T) above the upper limit of the normal range. 2. Patients scheduled to undergo coronary angiography with possible percutaneous coronary intervention (PCI) Lesion Characteristics on Diagnostic Coronary Angiography 1. De novo lesions in native coronary arteries found by diagnostic coronary angiography 2. Angiographic stenosis \<100% 3. Reference vessel diameter 2.5 mm - 4.0 mm by visual estimation Exclusion Criteria: General Exclusion Criteria 1. Subjects who are unable or unwilling to sign the informed consent form 2. Subjects being treated with anti-platelet medications other than aspirin prior to diagnostic catheterization including glycoprotein IIb/IIIa inhibitors. 3. Subjects with serious co-morbid conditions that in judgment of the investigator preclude inclusion in this study 4. Subjects with NYHA class III or IV heart failure or known left ventricular ejection fraction \< 30% 5. Subjects with an ST elevation myocardial infarction 6. Subjects with hemodynamic or electrical instability (including shock) 7. Subjects diagnosed with severe, non-catheter-related coronary artery spasm 8. Subjects who are or may be pregnant 9. Subjects with known allergies to contrast media 10. Subjects with renal failure as defined by eGFR \< 60. 11. History of TIA or stroke \< 6 months 12. History of hemorrhagic stroke 13. Hepatic insufficiency defined as liver cirrhosis, AST/ALT/Alkaline Phosphatase greater than 3 times the upper limit of normal or hyperbilirubinemia. Lesion Specific Exclusion Criteria These exclusion criteria apply to the target lesion to be imaged by OCT. 1. Lesion located in the left main coronary artery 2. Lesions that are heavily calcified 3. Lesions where OCT cannot be performed due to technical difficulties 4. Other lesions that the investigator deems inappropriate for the procedure such as sites with excessive tortuosity or low flow by TIMI grade. 5. Lesion in saphenous vein or arterial conduit