The recent availability of multislice CCTA allows for the noninvasive visualization of anatomic CAD with high- resolution images similar to invasive coronary angiography. As would be expected, CCTA and invasive angiography exhibit a high degree of concordance, as they are both anatomic tests, and CCTA is more sensitive in detecting obstructive CAD, especially at diameter stenosis #70%, than is nuclear MPI.76 The accuracy of a CCTA reader in estimating coronary stenosis within a vessel is hindered by the presence of dense coronary calcification and a tendency to overestimate the severity of lesions relative to invasive angiography.77 No direct comparisons of the effectiveness of a functional ap- proach with inducible ischemia or an anatomic approach assessing coronary stenosis have been completed in the noninvasive setting, although several randomized controlled trials (RCTs) are under way, which will directly or indirectly compare test modalities: PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain; clinicaltrials.gov identifier NCT01174550), RESCUE (Randomized Evalua- tion of Patients With Stable Angina Comparing Diagnostic Examinations; clinicaltrials.gov identifier NCT01262625), and ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches; clini- caltrials.gov identifier NCT01471522). In 2010, the United Kingdom s National Institute for Clinical Excellence Guidance for Chest pain of recent onset: Assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin provide, for a health- care system that allocates resources differently from that of the United States, recommendations for an initial assessment of CAD. This Guidance recommends beginning in people without confirmed CAD with a detailed clinical assessment and performing a 12-lead ECG in those in whom stable angina cannot be diagnosed or excluded on the basis of clinical assessment alone. The Guidance suggests that there is no need for further testing in those with an estimated likelihood ,10%. 