[The clinical value of sixteen-detector row computed tomography angiography for the assessment of coronary artery bypass graft]

Abstract

Objective: The aim of this study was to evaluate the value of sixteen-detector row computed tomography angiography (CTA) for the assessment of coronary artery bypass graft (CABG).

Methods: Sixty-two consecutive patients undergoing coronary artery bypass grafting were recruited. Among them, 6 patients were excluded from the study due to unfavorable control of heart rate. A total of 56 patients with 152 coronary artery bypass grafts (internal mammary artery, n = 48; saphenous venous grafts, n = 104) were examined by computed tomography angiography (CTA) with sixteen-detector row CT and by conventional invasive coronary angiography (CAG). All CT procedures were performed with retrospective electrocardiogram gating method. The patients' mean heart rate was 58 +/- 6 beats/minute. 120 ml of Visipaque 320 were continuously injected with the rate of 4.0 ml/sec during the procedure. The patency and the stenosis of coronary artery bypass grafts were evaluated by two experienced readers.

Results: All the coronary artery bypass grafts were visualized by CTA, and all the proximal bypass anastomoses and 71% of the distal bypass anastomoses were also visualized by CTA. Furthermore, 29 occlusions and 13 significant stenoses of coronary artery bypass grafts were detected by CTA. The comparison of the results between CTA and CAG showed that among all the 42 occluded and stenosed coronary artery bypass grafts detected by CTA, 34 were confirmed by CAG; among all the 110 normal coronary artery bypass grafts detected by CTA, 108 were confirmed by CAG. There were 8 false positive and 2 false negative findings, resulting in a sensitivity of 94%, a specificity of 95%, a positive predictive value of 86%, and a negative predictive value of 99%.

Conclusion: Sixteen-detector row CTA technology may provide a reliable visualization and higher diagnostic accuracy of coronary artery bypass grafts lesions. This technique can be used as a noninvasive procedure for the diagnosis of suspected coronary artery bypass grafts dysfunction.