Coronary computed tomography angiography: a method coming of age

In patients with stable symptoms suggestive of coronary artery disease (CAD), coronary CT angiography (CTA) allows for assessing several aspects of coronary atherosclerosis. Coronary artery stenoses are reliably detected, plaque formation can be quantified and characterized as calcified or non-calcified, and markers of potential instability such as expansive vascular remodeling, spotty calcification, and atheroma size can be described. As opposed to invasive coronary angiography, CTA visualizes the vessel lumen and wall. Being a purely anatomic test, even small plaques are detected with excellent sensitivity. At the other end of the spectrum, the hemodynamic significance of large plaque burden is sometimes overestimated. This may in part be corrected using mathematical modeling. Computational fluid dynamics of vascular anatomy and subtended myocardial mass provide for measures of CT-based fractional flow reserve (FFR_CT). Large prospective trials have demonstrated the diagnostic utility of CTA in particular for ruling out obstructive CAD. The ability to detect non-obstructive plaque allows for improved risk prediction in comparison with functional testing, because even patients with sub-clinical atherosclerosis can be identified and selected for preventive medical treatment. This has led to incorporating CTA as one of several possible diagnostic tests for the evaluation of stable CAD in the actual European guidelines. Recently, it has even been forwarded as the first-line diagnostic test in the United Kingdom. The clinical implications of novel quantitative CTA-derived parameters such as FFR_CT and non-calcified plaque volume are being examined in ongoing studies.