Abstract 3272: Diagnostic Accuracy of Multidetector 64-Slice CT Coronary Angiography in Assessing Patency of Coronary Artery Bypass Grafts
Background: CT angiography (CTA) has been considered as an attractive alternative to the gold standard invasive coronary angiography in the evaluation of coronary artery disease.
Aim: To prospectively evaluate the diagnostic accuracy of the multidetector 64-slice CT in assessment of the patency of coronary artery bypass grafts compared to invasive coronary angiography.
Methods: 122 bypass grafts (84 venous grafts, 38 mammary artery grafts) were evaluated in 38 consecutive patients (34 men and 4 women, age 64±8years). A contrast-enhanced 64-slice CT (Sensation 64, Siemens, Germany) was performed and compared to the invasive angiogram, using a scan protocol with 64x0.5mm slice collimation, 0.33s gantry rotation time and simultaneous ECG registration. All patients with heart rate above 65bpm at baseline received 50mg metoprolol orally (mean heart rate was 59±6). Bypass graft patency and the presence of stenosis as well as the proximal and distal anastomoses were evaluated by two experienced blinded readers.
Results: Overall 118 out of 122 bypass grafts (97%) were detected by CTA. The four un-visualized grafts were occluded at the time of the invasive coronary angiogram. Of the grafts visualized, 28 were totally occluded, 84 were patent, and 6 had significant stenoses which were confirmed by invasive angiography. 84% (76/90) of the distal anastomoses could be visualized very well and the remaining 16% (14/90) were not visualized well, in part due to vascular clips. 97% (87/90) of the patent grafts demonstrated good run-off distal to anastomoses, without ability to accurately evaluate retrograde flow. Interestingly, two grafts were not demonstrated by invasive angiography but were accurately detected by CTA and were found to be widely patent; one of them was a right internal mammary artery grafted to the LAD, and the other was a Y-graft originating from the inferolateral part of the aortic arch and grafted to the RCA and an obtuse marginal branch.
Conclusions: Multidetector 64-slice CTA is a valuable tool for direct visualization of coronary bypass grafts and assessment of their patency. Dysfunctional bypass grafts can be detected with very high diagnostic accuracy. With further improvements, CTA may become the preferred method for bypass graft assessment.