• Imaging And Diagnostics

Since the introduction of 64-detector row CT1 ,2 scanners in 2005, coronary CT angiography (CCTA) has developed into an accurate non-invasive method for direct visualisation of coronary arteries, coronary stenoses, and atherosclerotic plaque.3 These CT scanners have embodied a combination of favourable technological characteristics—including adequate volume coverage, high temporal resolution and reasonable spatial resolution—permitting the acquisition of images of the heart with reasonable breath holds, thus providing an advantage over prior generation 16-detector row scanners. Since its introduction, CCTA has experienced rapid adoption into daily clinical assessment of patients with suspected or known coronary artery disease (CAD), with resultant offerings of societal guidance documents such as the American College of Cardiology Appropriate Use Criteria, the American Heart Association Expert Consensus Statements, and Position Statements of the European Society of Cardiology.2 ,4 ,5 Without exception, these guidance documents have focused on the use of CCTA for anatomic assessment of CAD, owing to its previously demonstrated high diagnostic performance.

In this regard, more than 100 studies have been published which have compared CCTA to quantitative coronary angiography as a reference gold standard for stenosis severity. Several pooled meta-analyses have documented the high diagnostic sensitivity and specificity of CCTA for this end point, with performance measures ranging from 91–99% and 74–96%, respectively.6 Subsequent to these single centre studies—which were unvaryingly susceptible to referral, selection, and ascertain biases—three prospective multicentre studies have been published (table 1). In the first of these studies—the ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial—230 patients without known CAD underwent CCTA before clinically indicated invasive coronary angiography (ICA).7 This 16-centre US based study identified only 13.9% patients with a per-patient maximal ≥70% stenosis, thus underscoring a general ability for clinicians to identify precisely individuals with …