Comparison of Diagnostic Accuracy of 64-Slice Computed Tomography Coronary Angiography in Patients with Low, Intermediate, and High Cardiovascular Risk

Rationale and Objectives The aim of this study was to compare the diagnostic accuracy of 64-slice computed tomographic coronary angiography (CTCA) in groups of patients with low, intermediate, and high risk for coronary artery disease (CAD) events. Materials and Methods The institutional review board approved this study; written informed consent was obtained from all patients. Eighty-eight consecutive patients with suspected CAD (40 women; mean age, 64.3 ± 9.4 years; range, 39–82) underwent CTCA, calcium scoring, and invasive coronary angiography and were grouped according to their Framingham 10-year risk for hard coronary events into low (20%) risk categories. Significant stenoses (luminal diameter narrowing ≥50%) were assessed on an intention-to-diagnose-basis; no coronary segment was excluded and nonevaluative segments were rated false positive. To determine differences between groups, Kruskal-Wallis tests were performed for individually determined values of diagnostic performance. Results Per-patient sensitivity, specificity, negative predictive, and positive predictive values were 90.0%, 79.2%, 95.0%, and 64.3%, respectively, with low (n = 34), 87.5%, 92.3%, 85.7%, and 93.3%, respecitively, with intermediate (n = 29), and 100%, 75.0%, 100%, and 89.5%, respectively, with high risk (n = 25), with a trend toward higher positive predictive value ( P = .07). Per-segment negative predictive value was lower with high pretest probability ( P < .01). Mean calcium-score units were 90, 220, and 312 ( P = .23), and the prevalence of CAD was 29.4%, 55.2%, and 68.0% ( P < .01) with low, intermediate, and high risk. Conclusion Sensitivity and specificity of CTCA are not influenced by the prevalence of CAD, whereas the negative predictive value is lower and the positive predictive value tends to be higher in patients with a high prevalence of CAD.