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Diagnostic Accuracy of Computed Tomography Angiography in Patients After Bypass Grafting

Comparison With Invasive Coronary Angiography

Annick C. Weustink, MD^_*,, Koen Nieman, MD, PhD^_*,, Fransesca Pugliese, MD^_*,, Nico R. Mollet, MD, PhD^_*,, Bob W. Meijboom, MD^_*,, Carlos van Mieghem, MD^_*,, Gert-Jan ten Kate, MD^_*,, Filippo Cademartiri, MD, PhD, Gabriel P. Krestin, MD, PhD, Pim J. de Feyter, MD, PhD^_*,,_*

^_* Department of Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands
Department of Radiology, Erasmus Medical Center, Rotterdam, the Netherlands

^_* Reprint requests and correspondence: Dr. Pim J. de Feyter, Professor, Department of Cardiology, Thoraxcenter, Erasmus Medical Center, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands (Email: p.j.defeyter{at}erasmusmc.nl).

Objectives: We sought to evaluate the contribution of noninvasive dual-source computed tomography angiography (CTA) in the comprehensive assessment of symptomatic patients after coronary artery bypass grafting (CABG).

Background: Assessment of bypass grafts and distal runoffs by invasive coronary angiography is cumbersome and often requires extra procedure time, contrast load, and radiation exposure.

Methods: Dual-source CTA was performed in 52 (41 men, mean age 66.6 ± 13.2 years) symptomatic post-CABG patients scheduled for invasive coronary angiography. No oral or intravenous beta blockers or sedation were administered before the scan. Mean interval between CABG surgery and CTA was 9.6 ± 7.2 (range 0 to 20) years. Mean heart rate during scanning was 64.5 ± 13.2 (range 48 to 92) beats/min. Seventy-five percent of patients had both arterial and venous grafts. A total of 152 graft segments and 142 distal runoffs vessels were analyzed. Native coronary segments were divided into nongrafted (n = 118) and grafted segments (n = 289). A significant stenosis was defined as 50% lumen diameter reduction, and quantitative coronary angiography served as reference standard.

Results: The diagnostic accuracy of CTA for the detection or exclusion of significant stenosis in arterial and venous grafts on a segment-by-segment analysis was 100%. Sensitivity, specificity, positive predictive value, and negative predictive value to detect significant stenosis were 95% (95% confidence interval [CI]: 73% to 100%), 100% (95% CI: 96% to 100%), 100% (95% CI: 79% to 100%), 99% (95% CI: 95% to 100%) in distal runoffs respectively; 100% (95% CI: 97% to 100%), 96% (95% CI: 90% to 98%), 97% (95% CI: 93% to 99%), 100% (95% CI: 95% to 100%) in grafted native coronary arteries respectively; and 97% (95% CI: 83% to 100%), 92% (95% CI: 83% to 96%), 83% (95% CI: 67% to 92%), 99% (95% CI: 92% to 100%) in nongrafted native coronary arteries, respectively.

Conclusions: Noninvasive CTA is successful for evaluating bypass grafts in symptomatic post-CABG patients, whereas invasive coronary angiography is still required for the assessment of significant stenosis in distal runoffs and native coronary arteries.

Key Words: dual-source • computed tomography • CABG • bypass • angiography

Abbreviations and Acronyms   CABG = coronary artery bypass grafting   CT = computed tomography   CTA = computed tomography angiography   E = effective dose   ECG = electrocardiography   ICA = invasive coronary angiography   QCA = quantitative coronary angiography