Predicting early graft patency using transit-time flow measurement in internal thoracic artery-based composite coronary artery bypass grafting.

OBJECTIVE: Intraoperative graft assessment is essential for early graft patency after coronary artery bypass grafting (CABG); however, interpretation of transit-time flow measurement (TTFM) parameters in internal thoracic artery (ITA)-based composite CABG remains unclear. This study evaluated whether intraoperative TTFM parameters predict early graft patency after composite CABG. METHODS: We evaluated 274 patients who underwent isolated CABG using an in situ ITA-based composite graft and early postoperative angiography. TTFM parameters-mean graft flow (MGF), pulsatility index (PI), diastolic filling percentage (DF%), and percentage of backward flow (%BF) -were obtained for each distal anastomosis. Angiographic findings were classified as perfectly patent, bidirectionally competitive, unidirectionally competitive, or occluded. Receiver operating characteristic curve analyses determined optimal cutoff values and area under the curve (AUCs) for predicting competitive graft flow on early angiography. RESULTS: Among 894 distal anastomoses (median 3 [3.0, 4.0] per patient), 724 (81.0%) were perfectly patent, 88 (9.8%) bidirectionally competitive, 79 (8.8%) unidirectionally competitive, and 3 (0.3%) occluded. MGF, PI, DF%, and %BF differed significantly across graft-flow categories (all P < .001). Optimal cutoff values for predicting competitive graft flow were MGF 10 mL/min (AUC, 0.725), PI 3.1 (AUC, 0.699), DF% 60.0% (AUC, 0.635), and %BF 5.0% (AUC, 0.707) (all P < .001). Simultaneous fulfillment of all 4 thresholds yielded positive predictive values of 91.8% for perfectly patent grafts and 97.3% for functionally patent (perfectly patent or bidirectionally competitive) grafts. Optimal cutoff values for MGF, DF%, and %BF did not differ between left and right coronary territories (P = .265, P = .673, and P = .321, respectively). CONCLUSIONS: Intraoperative TTFM demonstrated good predictive performance for early postoperative competitive graft flow in patients undergoing CABG using an in situ ITA-based composite graft.