The development of a noninvasive, accurate imaging technique for assessing coronary artery bypass graft patency is of major clinical importance because increasing numbers of patients have undergone coronary artery bypass surgery. The electron beam tomography, by virtue of its rapid data acquisition time and good spatial resolution, may be useful in this regard. The purpose of this study is to determine the accuracy of three-dimensional coronary angiography by electron beam tomography (EBT) in the assessment of patency of coronary artery bypass grafts.

Twenty-five patients who had undergone coronary artery bypass graft surgery were included. All patients underwent EBT and conventional coronary angiography for the evaluation of the status of bypass grafts. Three dimensional reconstruction of the heart and bypass grafts were performed and compared with selective angiography of the bypass grafts.

Fifty-seven saphenous vein grafts (SVG) and 22 left internal mammary artery (LIMA) were evaluated for occlusion or patency. The sensitivity and specificity of EBT in the evaluation of LIMA patency were 80%, 82.4%, respectively. The sensitivity and specificity of EBT in the evaluation of SVG patency were 91.7% and 91.1%, respectively. The sensitivity and specificity of EBT in the evaluation of SVG according to the coronary territory were : 1) SVG to left anterior descending artery 100%, 100%:2) SVG to diagonal branch 100%, 100%:3) SVG to left circumflex artery 100%, 88.9%:4) SVG to right coronary artery 75%, 85.7%.

Three-dimensional coronary angiography by electron beam tomography is a promising, useful and relatively accurate diagnostic technique for the evaluation of graft patency in patients who had undergone coronary artery bypass graft surgery.