ECG-gated CT Angiography for the Assessment of Coronary bypass Graft Patency: the Influence of Heart Rate, Type of bypass Graft, Target Vessel and Surgical Technique on the Diagnostic Accuracy

ABSTRACT

PURPOSE: We wanted to evaluate the accuracy of using ECG-gated CT angiography (CTA) for the assessment of coronary bypass graft patency. MATERIALS AND METHODS: This study included 48 patients who underwent both CTA and conventional angiography to evaluate coronary bypass graft patency. CTA was performed with a 16-detector row multislice CT scanner. We calculated the sensitivity and specificity of CTA to detect occlusion of bypass graft that was equal to or greater than 50% of the expected diameter. Conventional angiography served as a gold standard. A total 160 grafts were evaluated. The diagnostic accuracy was evaluated according to a variety of factors (heart rate, types of bypass graft, target vessel, and surgical techniques). RESULTS: The overall sensitivity, specificity and accuracy of CTA were 83.9%, 95.4% and 93.1%, respectively. There was no significant statistical difference for each factor according to Fisher's exact test. Although the grafts anastomosed to the left circumflex arterial branches and a high heart rate showed a statistically significant high risk of misdiagnosis on the simple logistic regression test, a high heart rate was the only significant factor on the multiple logistic regression test (odds, 5.9). CONCLUSION: CTA provides for good noninvasive evaluation of the coronary bypass graft patency. The heart rate and the anastomosed vessel are factors that can influence the accuracy.