External support of a polytetrafluoroethylene graft improves patency for bypass to below-knee arteries

Patency and limb salvage after synthetic bypass to the arteries below the knee are inferior to that which can be achieved with autologous vein. The use of external support of synthetic polytetrafluoroethylene (PTFE) grafts to the below-knee position has been suggested to improve patency and limb salvage, a problem analyzed in this randomized clinical trial. We examined whether external graft support improves patency and/or limb salvage in patients undergoing reconstruction with synthetic PTFE grafts to the below-knee arteries.

Three hundred thirty-four patients with critical limb ischemia undergoing PTFE bypass to below-knee arteries were randomly assigned to have an ordinary PTFE graft or one with external support. Follow-up was scheduled until amputation, death, or at most 5 years, whichever event occurred first.

Patients in both the femoropopliteal and femorodistal groups were randomized to have an externally supported PTFE graft (101/195 patients in the femoropopliteal group and 72/139 patients in the femorodistal group). Follow-up information was available for 329 of 334 randomized patients (99%). At 1 year postprocedure, primary patency for below-knee bypass was 0.55 (95% confidence interval [CI], 0.47-0.64) with and 0.42 (95% CI, 0.34-0.50) without externally supported PTFE grafts, and secondary patency was 0.58 (95% CI, 0.51-0.67) and 0.47 (95% CI, 0.39-0.56), respectively. The corresponding figures for limb salvage were 0.75 (95% CI, 0.68-0.82) and 0.69 (95% CI, 0.62-0.77), respectively. The log rank test revealed statistically significant differences between patients with or without externally supported grafts for patency (primary patency: χ2=4.2 [degrees of freedom=1; P=0.041]; secondary patency: χ2=4.3 [degrees of freedom=1; P=0.037]) but not for limb salvage (limb salvage: χ2=0.2 [degrees of freedom=1; P=0.657]).

External support to a PTFE graft used for bypass to below-knee arteries improves primary and secondary patency but not limb salvage.