Prediction of graft patency during the year following coronary artery bypass grafting: Preoperative computed tomography-derived fractional flow reserve versus intraoperative transit-time flow measurement

Abstract

Background: Preoperative cardiac computed tomography-derived fractional flow reserve (CT-FFR) and intraoperative transit-time flow measurement (TTFM) values were compared with graft patency after coronary artery bypass grafting (CABG). Methods: One hundred and eight patients who underwent isolated CABG using an in situ internal thoracic artery (ITA)-based composite graft and whose CT-FFR values were obtained were included. TTFM values (mean graft flow [MGF; mL/min], pulsatility index [PI], and diastolic filling percentage [DF%]) were obtained for each anastomosis in all study patients. Early angiographies examined 342 anatomoses performed in all 108 patients, and 1-year angiographies examined 310 anastomoses performed in 97 patients (89.8%). Angiographic findings of graft flow were categorized as perfectly patent, bidirectionally competitive, unidirectionally competitive, and occluded. Receiver operating characteristic (ROC) curve analysis of CT-FFR and TTFM values for predicting angiographic findings was performed, and cutoff values and area under the ROC curve of CT-FFR and TTFM values were identified. Results: The early angiograms identified 281 (82.2%) perfectly patent grafts, 33 (9.6%) bidirectionally competitive grafts, 27 (7.9%) unidirectionally competitive grafts, and 1 (0.3%) occluded graft. These numbers were 278 (89.7%), 13 (4.2%), 8 (2.6%), and 11 (3.5%), respectively, on the 1-year angiograms. CT-FFR values in coronary arteries with perfectly patent, bidirectionally competitive, and unidirectionally competitive grafts were significantly different during the year (0.640, 0.807, and 0.816, respectively, in early angiograms [P < .001] vs 0.658, 0.841, and 0.857, respectively, in 1-year angiograms [P < .001]). Cutoff values of CT-FFR, MGF, PI, and DF% predicting competitive graft flow were 0.774, 11 mL/minute, 2.8, and 72%, respectively, in early angiograms and 0.767, 12 mL /minute, 2.8, and 58.0%, respectively, in 1-year angiograms. CT-FFR values better predicted the early and 1-year competitive graft flow compared to TTFM values (MGF, P < .001; PI, P < .001; DF%, P < .001). Conclusions: The diagnostic accuracy of CT-FFR values for predicting competitive graft flow during the year following CABG using an in situ ITA-based composite graft was high and superior to TTFM values. (J Thorac Cardiovasc Surg 2026;171:185-95)