To compare the image quality, evaluability, diagnostic accuracy, and radiation exposure of high-spatial-resolution (HR, 0.23-mm) computed tomographic (CT) coronary angiography with standard spatial resolution (SR, 0.625-mm) 64-section imaging in patients at high risk for coronary artery disease (CAD) by using invasive coronary angiography (ICA) as the reference method. Written informed consent was obtained from all patients, and the study protocol was approved by the institutional ethical committee. Patients at high risk for CAD (n = 184) who were scheduled for ICA were randomly assigned for study with SR (n = 91) or HR (n = 93) coronary CT angiography before they underwent ICA. To compare the two groups, the Student t test or Wilcoxon test were used to evaluate differences in continuous variables. The χ(2) test or Fisher exact test were used, as appropriate, for categorical data. The McNemar test was used to compare the diagnostic performance of coronary CT angiography versus that of ICA in each group. HR coronary CT angiography showed a higher image quality score (3.7 vs 3.4, P < .001) and evaluability (97% vs 92%, P < .002). In a segment-based analysis, HR coronary CT angiography showed a higher specificity, positive predictive value, and accuracy in comparison with SR coronary CT angiography (98%, 91%, and 99% vs 95%, 80%, and 95%, respectively; P < .001). Moreover, HR coronary CT angiography showed a better agreement with ICA for calcified plaques compared with SR coronary CT angiography and ICA (83% vs 53%, P < .001). In a patient-based analysis, HR coronary CT angiography showed higher specificity and accuracy compared with SR coronary CT angiography (91% and 98% vs 46% and 92%, respectively; P < .01). No differences in radiation exposure were found between the two groups. Improved evaluability and accuracy were seen with HR compared with SR coronary CT angiography of calcified coronary artery lesions, suggesting a potential use for this technology in patients at high risk for CAD.

Recent studies suggested that even non-obstructive coronary artery disease (CAD) increases major cardiovascular adverse events (MACE) rate. Aim of this study was to evaluate whether coronary computed tomography angiography (CCTA) may detect specific plaque characteristics that may affect prognosis in patients with non-obstructive CAD. We enrolled 245 patients who underwent CCTA between April 2004 and April 2007 for suspected CAD and were found to have non-obstructive CAD. Positive remodelling index (PRI), low-attenuation plaque (LAP), plaque burden (PB), spotty calcification (SC), and napkin-ring sign (NRS) have been evaluated for each coronary plaque detected. Acute coronary syndrome, all-cause/cardiac death, and very late elective revascularization (vl-ER) were the endpoints of the study. A total of 28 events were recorded (2 STEMI, 4 NSTEMI, 6 UA, 2 cardiac deaths, 4 non-cardiac death, and 10 vl-ERs) at long-term follow-up (98 ± 20 months). When adjusted for significant clinical variables PRI > 1.4 (HR 3.31 CI 95% 1.11–9.91, P = 0.0392), LAP (HR 8.45 CI 95% 2.22–32.21, P = 0.0019), PB > 0.7 (HR 5.25 CI 95% 1.45–19.03, P = 0.0120), and NRS (HR 12.52 CI 95% 1.51–103.90, P = 0.0198) were still significantly associated with higher rate of hard cardiac events at follow-up. The Kaplan–Meyer curves confirmed lower cumulative hard cardiac events-free survival in patients presenting at least one coronary plaque with two or more high-risk characteristics when compared with patients with no lesion with more than one high-risk plaque characteristics (log-rank P < 0.0001). High-risk plaque characteristics at CCTA (PRI > 1.4, PB > 0.7, LAP, and NRS) seem to be promising for risk stratification of patients with non-obstructive CAD.