Outpatients scheduled to undergo cardiac catheterization and coronary angiography for the specific indication of inconclusive or indeterminate stress tests will be considered for this study. Patients will be initially screened by their cardiologist for the presence of inclusion/exclusion criteria, as well as pre-test and post-test likelihood of CAD.16, 17 All patients must have undergone a stress (exercise or pharmacologic) test within the past 3 months. After consent, patients will be randomized 1:1 to undergo CCTA or cardiac catheterization. The decision whether or not to proceed with subsequent invasive cardiac catheterization (CCTA arm) or revascularization (catheterization arm) will be made by the patient's primary and interventional cardiologists respectively.

Inclusion:

1. Chest pain or other symptoms suggestive of coronary artery disease.
2. Pharmacologic/exercise stress test with SPECT (nuclear myocardial-heart perfusion imaging) within the past 3 months.
3. "Discordant or conflicting findings" clinical and stress results as outlined above.
4. Scheduled to undergo cardiac catheterization.
5. Able to provide informed consent.
6. Age equal to or greater than 18 years.

Exclusion:

1. Presence of pre-existing heart disease (prior heart attack, prior angiographic evidence of significant heart disease, prior heart surgery) or cardiomyopathy (ejection fraction less than or equal to 45%)
2. History of high blood pressure with severe left ventricular hypertrophy (thicken heart muscle), history of cor pulmonale (right heart chamber failure due to elevated blood pressures in the arteries delivering blood to the lungs).
3. Kidney insufficiency (creatinine greater than or equal to 1.6) or kidney failure requiring dialysis.
4. Inability or refusal to provide informed consent.
5. Psychological unsuitability or extreme claustrophobia (fear of closed in spaces).
6. Pregnancy or unknown pregnancy status.
7. Age less than 18 years.
8. Patients with known allergy to iodinated contrast, unable to tolerate pre-medication.
9. Inability to tolerate beta-blockers (medication to slow the heart rate), including those with COPD or asthma requiring maintenance inhaled bronchodilators or steroids, complete heart block, second-degree atrioventricular block.
10. Computed tomography imaging, or contrast administration, within the past 48 hours.