Diagnostic utility of transit time flow measurement for predicting early coronary bypass graft occlusion

The study objective was to evaluate the predictive value of intraoperative graft flow and pulsatility index for early in-hospital graft occlusion.

We prospectively included 634 patients undergoing isolated coronary bypass grafting surgery between 2020 and 2025. To assess bypass flow, intraoperative transit-time flow measurements were performed. Graft patency was determined in all patients by coronary computed tomography angiography or coronary angiography at discharge. Receiver operating characteristic analysis using the Youden index identified optimal intraoperative flow and pulsatility index thresholds for predicting in-hospital graft occlusion. A logistic regression-based nomogram using flow and pulsatility index was constructed to estimate occlusion risk, and multilevel mixed-effects models were applied to assess independent predictors of graft failure.

The incidence of early graft occlusion was 7.9% (n = 50) and associated with female sex, hypercholesterolemia, longer surgery, reoperations, and prolonged hospital stay. Venous grafts were associated with higher occlusion rates at the patient level (6.5% vs 3.0%, P = .004), with a similar trend observed at the graft level (3.1% vs 1.8%, P = .07). In conduit-specific analysis, every 10 mL/min increase in venous graft flow was associated with a 38% reduction in occlusion (odds ratio, 0.62; P < .001), whereas arterial grafts showed no such association with intraoperative flow or the pulsatility index. Optimal prognostic thresholds for venous grafts were identified at a mean flow less than 50 mL/min and a pulsatility index greater than 1.7.

The incidence of early graft occlusion is significantly higher in venous conduits. Occlusion is associated with intraoperative graft flow, whereas no statistically significant relationship with these parameters was detectable in arterial grafts in this cohort.