Prognostic significance of intraoperative graft flow on long-term patency of below knee popliteal and tibial bypasses with autologous vein in patients with chronic limb-threatening ischemia.

Abstract

Intraoperative graft flow (GF) is a quick, composite measure of bypass graft status, encompassing adequacy of conduit, technique as well as inflow/outflow. The aim of this study was to evaluate the prognostic significance of GF on long-term patency of below-knee (BKPB) popliteal and tibial (TB) bypasses performed with autogenous vein conduit in patients with chronic limb-threatening ischemia (CLTI). Data from consecutive patients who underwent BKPB or TB for CLTI using autologous vein between July 2003 and July 2023 and had intraoperative GF measurement (Optima Flow-QC transit-time ultrasound) were retrospectively reviewed. Primary endpoints were primary patency (PP), primary assisted patency (PAP), secondary patency (SP), and major limb amputation. Youden index was used to determine cutoff of GF. There were 177 bypasses in 163 patients (68.9% males; median age, 71 years), 68.4% with Rutherford IV ischemia and 31.6% with Rutherford V/VI ischemia. Comorbidities included hypertension (84.2%), diabetes mellitus (49.2%), coronary artery disease (59.3%), and end-stage renal disease (6.8%), and 26% were active smokers. Outflow targets included BKP or TP trunk in 36.2% and tibial in 63.8%. Venous conduits used were single-segment great saphenous vein (57.6%), arm vein (3.4%), and composite vein (39.0%). Median GF was 132 mL/min (BKPB vs TB; 150 vs 120 mL/min; P = .054). Median clinical follow-up was 47 months (interquartile range, 18-98 months). PP, freedom from major amputation, and overall survival at 1 year following BKPB and TB were 57.6%, 100%, and 86.9% and 40.3%, 86.8%, and 88.2%, respectively. On multivariate analysis, Rutherford VI (hazard ratio [HR], 3.2), GF <110 mL/min (HR, 1.7), and composite vein conduit (HR, 1.7) were associated with loss of patency. On Kaplan-Meier analysis, in grafts with GF >110 mL/min, PP, PAP and SP at 1 year (54%, 77%, and 85%) and 5 years (37%, 68%, and 70%) were significantly higher than those with GF <110 mL/min (1 year: 31%, 48%, and 66%; 5 years: 16%, 34%, and 50%; P < .01). In addition to nonmodifiable factors such as outflow target and composite vein conduit, intraoperative GF flow is an independent predictor of loss of patency of distal bypass grafts with vein conduit in patients with CTLI. This information can be used to modify the surveillance protocol and consider anticoagulation.