Evaluation of a Combined Near Infrared Spectroscopy (NIRS) and Intravascular Ultrasound (IVUS) Catheter for Detection of Lipid Rich Plaque

Inclusion Criteria: Patient Characteristics 1. Males and non-pregnant females \> 18 and \< 79 years of age 2. Patients referred for diagnostic coronary angiography who are found to have lesions in native coronary arteries which will be treated by percutaneous coronary intervention (PCI) (or patients with known coronary lesions who are referred for planned PCI) 3. Able to give written informed consent Lesion Characteristics 1. Lesion in native coronary artery 2. Angiographic stenosis \> 50% 3. Reference vessel diameter 2.5 mm - 4.0 mm by visual estimation 4. Subjects who have successful PCI and OCT General Exclusion Criteria 1. Subjects who are unable or unwilling to sign the informed consent form 2. Subjects with serious co-morbid conditions that in judgment of the investigator preclude inclusion in this study (such as terminal cancer, life expectancy \< 6 months, Liver Function Tests (LFTs) \> 3 times Upper Limit of Normal (ULN), or post-transplant) 3. Subjects with New York Heart Association (NYHA) class III or IV heart failure or known left ventricular ejection fraction \< 30% 4. Subjects who have experienced an ST-elevation myocardial infarction (STEMI) within 72 hours prior to the procedure 5. Subjects with hemodynamic or electrical instability (including shock) 6. Subjects diagnosed with severe, non-catheter-related coronary artery spasm 7. Subjects who are or may be pregnant 8. Subjects with known allergies to contrast media 9. Subjects with renal failure as defined by estimated Glomerular Filtration Rate (eGFR) \< 60. 10. History of Transient Ischemic Attack (TIA) or stroke \< 6 months Lesion Specific Exclusion Criteria These exclusion criteria apply to the target lesion to be imaged by NIRS IVUS. 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 lesions with excessive tortuosity, presence of thrombus, low flow by TIMI grade.