Highly accurate coronary angiography with submillimetre, 16 slice computed tomography

Objective: To assess submillimetre coronary computed tomographic angiography ( CTA) in comparison with invasive quantitative coronary angiography as the gold standard and to examine the effect of significant coronary artery calcification ( CAC), which is known to impede lumen visualisation, on the accuracy of the examination. Methods: After invasive coronary angiography, 58 patients underwent coronary imaging with a GE Lightspeed 16 computed tomography ( CT) system. CAC was quantified after an ECG triggered acquisition with a low tube current. Coronary CTA was performed with retrospective ECG gating and a 16 60.63 mm collimation and was reconstructed with an effective 65 - 250 ms temporal resolution. All 13 major coronary artery segments were evaluated for the presence of greater than or equal to 50% stenosis, and compared with the gold standard. Results: One patient moved and could not be evaluated. All segments ( except occluded segments) were evaluated for 57 patients. Overall the accuracy of coronary CTA for detection of greater than or equal to 50% stenosis was: sensitivity 83%, specificity 97%, positive predictive value 80%, and negative predictive value 97%. The number of diseased coronary arteries was correctly diagnosed in 34 of 38 ( 89%) patients overall. Altogether 21 of 57 ( 37%) patients had a CAC score greater than or equal to 400, which was predefined as representing significant CAC. Excluding these patients from the analysis improved the accuracy of coronary CTA to a sensitivity of 89%, specificity 98%, positive predictive value 79%, and negative predictive value 99%. Conclusions: Non- invasive coronary angiography with submillimetre CT is reliable and accurate. It appears that a subgroup of patients may be selected based on CAC score in whom the investigation has even higher accuracy. Coronary CTA has reached the stage where it should be considered for a clinical role. Further research is required to define this role.