The purpose of these studies was to define the concordance between CCTA and a reference standard of ICA, and, thus, each of these studies was limited to patients being clinically referred for ICA. The first of these trials was the ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial, a 16-center U.S.-based study that restricted analysis to patients without known CAD undergoing CCTA before elective ICA (7). Reasons for ICA referral included stable chest pain syndrome and/or abnormal functional stress testing results. Among the 230 subjects, only 13.9% were found to have obstructive CAD at the ≥70% stenosis threshold by quantitative coronary angiography. Although the prevalence of CAD in the ACCURACY trial cohort highlighted the imperfections of current clinical and imaging algorithms for the proper identification of individuals with obstructive CAD, it nevertheless permitted an assessment of CCTA diagnostic performance in a patient population for whom CCTA use is generally advocated. The diagnostic sensitivity, specificity, and positive predictive value (PPV) and negative predictive value (NPV) of CCTA to detect a ≥70% stenosis in this population were 94%, 83%, 48%, and 99%, respectively. Importantly, these test characteristics were calculated reporting all vessel segments, without exclusion of patients for baseline heart rate, coronary artery calcium score (CACS), or body mass index; which is in contrast to many previous single-center studies that reported higher diagnostic performance characteristics. The area under the receiver-operator characteristic curve, which describes the discriminatory power of diagnostic testing across a wide range of cutoff values, for identification of patients with ≥70% stenosis was 0.95, thereby definitively establishing the high diagnostic accuracy for both detection and exclusion of obstructive coronary artery stenosis in individuals without known CAD with a low prevalence of CAD (Figure 1).