VESS01 - Midterm Outcomes and Predictors of Failure of Lower Extremity Bypass to Para-malleolar and Pedal Targets

Objectives: Studies suggest that the frequency of distal lower extremity bypass (LEB) for infra-popliteal critical limb threatening ischemia (IP-CLTI) has significantly decreased. We analyzed the contemporary outcomes and predictors of 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 (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, and 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). Cohort demographics and common comorbid conditions are summarized in Table 1. The majority of cases presented with Rutherford Class (RC) 5/6 ischemia (81.25%), with RC 4 (14.5%) and RC 1-3 (4.25%) comprising the remainder. 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% (Table I).On unadjusted Kaplan-Meier survival analysis primary patency was 50.56%±3.6%, primary assisted patency was 58.79%±4.03%, secondary patency was 60.48%±4.12%, MALE was 63.49%±3.27%, and amputation free survival was 71.71%±0.98% (Fig 1) at 2 years. In an adjusted cox regression model [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 and prior ipsilateral vascular interventions (open/endovascular) were predictors of loss of primary patency and increased MALE, while high center volume (>60 procedures/center over total time period) was associated with increased primary patency, and lower MALE at 2 years (Table I). Predictors of lower amputation free survival at 2 years included increasing age, dialysis dependence, and conduits other than GSV (Table I).

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. Choice of conduit and prior vascular interventions are the most important predictors of failure, while high center volume is associated with increased patency and lower MALE. Bypasses to distal targets should be performed at high volume centers and GSV should be utilized to optimize graft patency and limb salvage.