64 slice computed tomography-a novel diagnostic method for evaluation of patients after coronary artery bypass grafts

Multislice computed tomography (CT) is widely used in analysing the native coronary arteries. The usefulness of 64 slice CT in patients with coronary artery bypass grafts (CABG) is analysed in the present study.

Sixty-five patients (59 [92%] males and 6 [8%] females with the mean age of 59 ± 9.1 years) underwent 64 slice CT and a total of 186 bypass grafts (62 arterial and 124 venous grafts) were analysed using 64 slice CT. Bypass grafts and native vessels with the diameter of >1.5 mm were evaluated for the presence of significant stenosis of >70%. In all patients invasive coronary angiogram was done.

On the whole 43 venous grafts and 3 arterial grafts were found to be occluded. Majority of the grafts were occluded at the ostium. It was observed that the 64 slice CT was 90% sensitive and 96% specific for the evaluation of bypass grafts. It had 95% positive predictive value and 93% negative predictive value for predicting the luminal narrowing of grafts. For the assessment of arterial graft, it was 80% sensitive, 100% specific with a positive predictive value of 100% and negative predictive value of 93%. For the evaluation of venous grafts, the sensitivity, specificity, positive, and negative predictive value were 94%, 94%, 93%, and 94%, respectively.

We conclude that the 64 slice CT is a highly reliable diagnostic tool with a very high negative predictive value for evaluating patients following CABG.