 1,142 consecutive patients who present to North Shore University Hospital Emergency Department ED for CCTA due to chest pain or angina over a two year period and meeting the study inclusion criteria are eligible for the study Figure 1. The investigators will employ CCTA-appropriateness criteria to ensure proper selection of patients, derived from the Appropriate Use Criteria for Cardiac Computed Tomography published in 2010 and jointly authored by multiple societies including American College of Cardiology Foundation ACCF, Society of Cardiovascular Computed Tomography SCCT, and American College of Radiology ACR 11. FFR-CT measurements will be performed following CCTA scan acquisition on software developed by Toshiba America Medical Systems, Inc. All eligible patients will undergo 320-slice multi detector CCTA and CT-FFR measurements. The severity of the stenosis will be determined on site by level III CCTA readers. 