Midterm Outcomes and Predictors of Failure of Lower Extremity Bypass to Paramalleolar and Pedal Targets

Objectives The frequency of distal lower extremity bypass (LEB) for infra-popliteal critical limb threatening ischemia (IP-CLTI) has significantly decreased. Our goal was to analyze the contemporary outcomes and factors associated with failure of LEB to para-malleolar and pedal targets. Methods We queried the VQI infra-inguinal database from 2003-2021 to identify LEB to para-malleolar or pedal/plantar targets. Primary outcomes were graft patency, major adverse limb events [vascular re-intervention, above ankle amputation] (MALE), and amputation-free survival at 2 years. Standard statistical methods were utilized. Results We identified 2331 LEB procedures (1265 anterior tibial at ankle/dorsalis pedis, 783 posterior tibial at ankle, 283 tarsal/plantar). The prevalence of LEB bypasses to distal targets has significantly decreased from 13.37% of all LEB procedures in 2003 to 3.51% in 2021 (p<0.001). The majority of cases presented with tissue loss (81.25. Common post-operative complications included major adverse cardiac events (8.9%) and surgical site infections (3.6%). Major amputations occurred in 16.8% of patients at 1 year. Post-operative mortality at 1 year was 10%.On unadjusted Kaplan-Meier survival analysis at 2 years, primary patency was 50.56%±3.6%, MALE was 63.49%±3.27%, and amputation-free survival was 71.71%±0.98%. In adjusted analyses [adjusted for comorbidities, indication, conduit type, urgency, prior vascular interventions, graft inflow vessel (femoral/popliteal), concomitant inflow procedures, surgeon and center volume] conduits other than GSV (p<0.001) were associated with loss of primary patency and increased MALE. High center volume (>5 procedures/year) was associated with improved primary patency (p=0.015), and lower MALE (p=0.021) at 2 years. Conclusions Despite decreased utilization, open surgical bypass to distal targets at the ankle remains a viable option for treatment of IP-CLTI with acceptable patency and amputation-free survival rates at 2 years. Bypasses to distal targets should be performed at high volume centers to optimize graft patency and limb salvage and minimize re-interventions.