8mm Conduit Outperforms 6mm Conduit in Extra-anatomic Bypass

Extra-anatomic bypass is an important tool in relieving supra-inguinal occlusive disease. These bypasses are frequently conducted with prosthetic material, commonly available in 6-mm and 8-mm sizes. Previous studies have demonstrated infra-inguinal bypass has improved patency when graft size is 6 mm or greater. This study aimed to examine outcomes of 6-mm vs 8-mm prosthetic graft use in extra-anatomic bypasses. A retrospective analysis of the Vascular Quality Initiative supra-inguinal database (2010-2022) was conducted. Patients undergoing either axillary-femoral or femoral-femoral prosthetic bypass with available conduit size data were included. Primary endpoints included graft patency and major adverse limb events (MALE). A logistic regression analysis was performed of demographic and operative variables to determine if any factors contributed to the selection of graft size. Then, multivariable Cox regression analysis was conducted in groups based on prosthetic diameter (6 mm vs 8 mm), controlling for these factors. Seven mm was excluded from formal regression analysis due to small sample size but included in survival curves to demonstrate the stepwise impact of graft size. A total of 6463 patients were included for analysis; 2355 axillary-femoral bypasses and 4128 femoral-femoral bypasses. Of these, 1071 patients underwent bypass with 6-mm graft, and 5392 patients underwent bypass with 8-mm graft. Significant predictors (P < .05) of 8-mm graft use in both types of extra-anatomic bypass included male gender, body mass index (BMI) of 25-35 kg/m2, and common femoral as distal target when compared to profunda, superficial femoral artery, and other distal vessels. The most significant predictor (P < .001) of improved primary patency in both types of extra-anatomic bypass examined was larger conduit diameter (8 mm vs 6 mm axillary-femoral hazard ratio [HR], 0.5; femoral-femoral HR, 0.66). Cox regression curves by graft size were generated for both axillary-femoral and femoral-femoral bypasses (Figs 1 and 2), which demonstrated significantly higher primary patency in patients with 8-mm bypasses over time. Improved performance in 8-mm graft compared with 6-mm graft was additionally demonstrated in primary-assisted patency, secondary patency, and MALE regression curves with P < .001 for both axillary-femoral and femoral-femoral bypasses. In this retrospective analysis of extra-anatomic bypasses, 8-mm grafts had significantly improved patency rates and fewer MALE when compared with 6-mm grafts over time. Male sex and body mass index were associated with larger diameter bypass use; after controlling for these preoperative factors, 8-mm grafts still outperformed 6-mm grafts. Vascular surgeons should be cognizant of the potential implications in limb salvage when selecting prosthetic graft for extra-anatomic bypass.Fig 2Primary patency of axillary-femoral bypass over time by graft size.View Large Image Figure ViewerDownload Hi-res image Download (PPT)