Accuracy of 64-Slice Multidetector Computed Tomography for Diseased Coronary Artery Graft Detection

Background: Sixty-four-slice multidetector computed tomography (64-MDCT) has been shown to be a feasible modality for diagnosing coronary artery disease. We studied the accuracy of 64-MDCT in the detection of diseased grafts and also evaluated its limitations. Methods: This study comprised 19 patients who underwent coronary artery bypass grafting and both invasive coronary angiography (ICA) and 64-MDCT. The 64-MDCT images were analyzed for bypass graft occlusion and significant stenosis (>50%) of the anastomosis, and the results were compared with those of ICA. Results: A total of 90 anastomoses, including 25 proximal anastomoses, were evaluated. Of 65 distal anastomoses, including 5 previously occluded grafts in redo cases, 12 distal anastomoses were identified by 64-MDCT as occluded. In comparison, only 10 grafts were identified as occluded by ICA. The sensitivity, specificity, positive predictive value, and negative predictive value for patency were 100% (10 of 10), 96.5% (55 of 57), 83.3% (10 of 12), and 100% (55 of 55), respectively. The ICA patent grafts were evaluated with respect to stenosis. Invasive coronary angiography identified significant stenosis at only 1 site, whereas 64-MDCT showed significant stenosis at 6 sites. The sensitivity, specificity, positive predictive value, and negative predictive value for stenoses were 100% (1 of 1), 93.1% (67 of 72), 16.7% (1 of 6), and 100% (67 of 67), respectively. Conclusions: Although 64-MDCT demonstrated diagnostic accuracy in evaluating bypass grafts, limitations of this method include false positive results in cases of competitive flow between the graft and the native coronary artery.