Aims: The positive predictive value of multidetector computed tomography angiography (CTA) for detecting significant stenosis remains limited. Possibly CTA may be more accurate in the evaluation of atherosclerosis rather than in the evaluation of stenosis severity. However, a comprehensive assessment of the diagnostic performance of CTA in comparison with both conventional coronary angiography (CCA) and intravascular ultrasound (IVUS) is lacking. Therefore, the aim of the study was to systematically investigate the diagnostic performance of CTA for two endpoints, namely detecting significant stenosis (using CCA as the reference standard) vs. detecting the presence of atherosclerosis (using IVUS as the reference of standard).
Methods and results: A total of 100 patients underwent CTA followed by both CCA and IVUS. Only those segments in which IVUS imaging was performed were included for CTA and quantitative coronary angiography (QCA) analysis. On CTA, each segment was evaluated for significant stenosis (defined as ≥ 50% luminal narrowing), on CCA significant stenosis was defined as a stenosis ≥ 50%. Second, on CTA, each segment was evaluated for atherosclerotic plaque; atherosclerosis on IVUS was defined as a plaque burden of ≥ 40% cross-sectional area. CTA correctly ruled out significant stenosis in 53 of 53 (100%) patients. However, nine patients (19%) were incorrectly diagnosed as having significant lesions on CTA resulting in sensitivity, specificity, positive, and negative predictive values of 100, 85, 81, and 100%. CTA correctly ruled out the presence of atherosclerosis in 7 patients (100%) and correctly identified the presence of atherosclerosis in 93 patients (100%). No patients were incorrectly classified, resulting in sensitivity, specificity, positive, and negative predictive values of 100%. Conclusions The present study is the first to confirm using both CCA and IVUS that the diagnostic performance of CTA is superior in the evaluation of the presence or the absence of atherosclerosis when compared with the evaluation of significant stenosis.