Predictors of Amputation-Free Survival and Wound Healing After Infrainguinal Bypass with Alternative Conduits

OBJECTIVE:Inadequate vein quality or prior harvest precludes use of autologous single segment greater saphenous vein (ssGSV) in many patients with chronic limb threatening ischemia (CLTI). Predictors of patient outcome after infrainguinal bypass with alternative (non-ssGSV) conduits are not well understood. We explored whether limb presentation, bypass target, and conduit type were associated with amputation-free survival (AFS) after infrainguinal bypass using alternative conduits. METHODS:A single center retrospective study (2013-2020) was conducted of 139 infrainguinal bypasses performed for CLTI with cryopreserved ssGSV (cryovein) (n=71), PTFE (n=23), or arm/spliced vein grafts (n=45). Characteristics, WIfI stage, and outcomes were recorded. Multivariable cox proportional hazards and classification and regression tree analysis (CART) modeled predictors of AFS. RESULTS:Within 139 cases, the mean age was 71 years, 59% of cases were male, and 51% were non-elective. More subjects undergoing bypass with cryovein were WIfI stage 4 (41%) compared to PTFE (13%) or arm/spliced vein (27%) (P=0.04). Across groups, AFS at 2 years was 78% for spliced/arm, 79% for PTFE, and 53% for cryovein (adjusted hazard ratio [aHR] for cryovein: 2.5, P=0.02). Among cases using cryovein, CART showed that WIfI stage 3 or 4, age>70, and prior failed bypass were predictive of the lowest AFS at 2 years of 36% vs AFS of 58-76% among subgroups with <2 of these factors. While secondary patency at 2 years was worse in the cryovein group (26% vs 68% and 89% in arm/spliced and PTFE groups, P<0.01), in subjects with tissue loss there was no statistically significant difference in wound healing in the cryovein group (72%) compared to other bypass types (72% vs.87% respectively, P=0.12). CONCLUSIONS:In patients with CLTI lacking suitable ssGSV, bypass with autogenous arm/spliced vein or PTFE has superior AFS compared to cryovein, though data were limited with PTFE conduits for distal targets. Despite poor patency with cryovein, wound healing is achieved in a majority of cases, though it should be used with caution in older patients with high WIfI stage and prior failed bypass given the low rates of amputation free survival.