Utility of Coronary CT Angiography and stress SPECT Myocardial Perfusion Imaging for graft disease assessment in symptomatic patients after coronary artery bypass graft surgery.

Background: Graft occlusions are commonly present in symptomatic patients after coronary artery bypass surgery (CABG). The aim of this study was to evaluate the diagnostic accuracy of coronary computed tomography angiography (CCTA) and stress single photon emission computed tomographic (SPECT) myocardial perfusion imaging (MPI) for detecting graft disease in symptomatic post-CABG patients. Methods: This was a prospective, single centre study of 100 symptomatic post-CABG patients with native coronary artery/graft occlusions on invasive angiography (CAG). Grafts were evaluated for degree of stenosis qualitatively on CCTA. Reversible perfusion defects were graded using summed difference score (SDS) on MPI. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of CCTA and MPI were evaluated against CAG. Results: CCTA identified 17/31 (55%), 30/43 (70%) and 18/19 (95%) patients with ≥50% stenosis of arterial, venous and both grafts respectively with specificity and PPV of 100%. Reversible perfusion defects were present in 81% of the patients with a mean SDS score of 5.4 ± 3.39 and sensitivity of 84%. Accuracy of CCTA and MPI for detection of graft occlusions were 99% and 84% respectively. 63/65 (97%) patients with ≥50% stenosis of grafts had ≥ 5 SDS score (moderate to severe grade ischemia) and 64% patients were revascularized. Conclusion: CCTA has a comparable diagnostic accuracy to CAG and can be used as an initial investigation in symptomatic post-CABG patients. Reversible perfusion defects on stress MPI help to risk stratify symptomatic post-CABG patients and guide further treatment. Hemodynamically significant occlusions may benefit from revascularization. [ABSTRACT FROM AUTHOR]