Identification of non-obstructive coronary artery disease by coronary CT angiography in patients with normal coronary arteries in preceding invasive catheterization

Introduction: Invasive coronary catheterization reflects the current gold standard to identify coronary artery stenosis. All the same, the sensitivity to identify non-obstructive coronary artery disease is limited. Non-invasive coronary CT angiography is capable to detect coronary artery plaque. We performed coronary dualsource CT angiography to determine the incidence of non-obstructive coronary artery disease in patients with exclusion of coronary artery disease in preceding invasive catheterization. Methods: This is a retrospective analysis of 60 consecutive symptomatic patients (32 men, 28 women, age 61±11 years) with intermediate pretest-likelihood for coronary artery disease and absence of detectable coronary artery disease in invasive catheterization who subsequently underwent coronary DSCT angiography (predominantly prospectively triggered at 70% of RR-interval, body-weight adapted energy modulation between 100-120 kV and 320-440 mAs, 2x128x0,6 mm collimation, 60 ml contrast, flow rate 6 ml/s). Two independent observers evaluated the DSCT data sets with respect to the presence or absence of coronary calcified and non-calcified atherosclerotic plaque on a per-segment basis using the SCCT 18 segment model of the coronary artery system. Results: 45 of 60 patients (75%) with exclusion of coronary artery disease in preceding invasive catheterization showed non-obstructive disease in DSCT angiography. In vessel-based analysis, plaque was present in 14/60 (23%) left main coronary arteries, 41/60 left anterior descending arteries (68%) as well as 21/60 circumflex arteries (35%) and 24/60 right coronary arteries (40%). In a per segment analysis, 163 of 1080 coronary artery segments had detectable plaque. Interobserver agreement was 100% (kappa 1.0) on a per patient basis, 98% (kappa 0.98; [CI 0.96; 1.0]) on a per vessel basis and 84% (kappa 0.84; [CI 0.76; 0.92]) on a per segment basis. Patients with detectable plaque were older (p<0.005) and showed significant more likely hypertension (p<0.019) as compared to individuals without coronary atherosclerotic lesions in CT. Conclusion: In a significant number of patients with previous exclusion of coronary artery disease by invasive catheterization, DSCT angiography showed non-obstructive coronary plaques with a higher sensitivity. The detection of plaque may have an impact regarding the intensity of risk modifying therapy.