Improved noninvasive assessment of coronary artery bypass grafts with 64-slice computed tomographic angiography in an unselected patient population

Abstract

Objectives: In this prospective evaluation we investigated the accuracy of 64-slice computed tomography angiography (CTA) in an unselected but symptomatic patient population for detection of stenoses in bypass grafts when compared with invasive angiography.

Background: The assessment of significant stenosis in bypass grafts is important for patients with recurrent angina symptoms after bypass surgery.

Methods: High-resolution 64-slice computed tomography (0.6 mm collimation, 330 ms gantry rotation time) and invasive angiography were performed in 138 consecutive patients with a total of 418 bypass grafts. Relevant stenosis was defined as diameter reduction > or =50%. During CTA, arrhythmias were present in 42 (30%) patients who were not excluded from the analysis.

Results: The assessment of stenosis or occlusion of bypass grafts resulted in a sensitivity of 97%, specificity of 97%, and positive and negative predictive values of 93% and of 99%, respectively. The diagnostic accuracy for the detection of graft occlusion or stenosis did not differ between arterial and venous grafts. The evaluability of bypass grafts was significantly lower in patients with arrhythmias or with heart rates > or =65 beats/min during scanning. However, in the assessment of evaluable bypass grafts, no significant differences were detected in the diagnostic accuracy in these subgroups.

Conclusions: This large prospective study demonstrates that 64-slice CTA is a reliable method for the assessment of bypass graft patency and stenoses even in an unselected "real-world" patient population.