Direct oral anticoagulants over warfarin at discharge associated with improved survival and patency in infra-geniculate bypasses with prosthetic conduits

Abstract

Objective: There is no consensus on the optimal anticoagulant regimen following lower extremity bypass. Historically, warfarin has been utilized for prosthetic or compromised vein bypasses. Direct-acting oral anticoagulants (DOACs) are increasingly replacing warfarin in this context, but their efficacy in bypass preservation has not been well-studied. Recent studies have shown that DOACs may improve outcomes following bypasses; however, it is unclear if this is dependent upon type of bypass conduit. The goal of this study was to evaluate whether a difference exists between vein and prosthetic infra-geniculate bypasses outcomes based on the anticoagulant utilized on discharge, warfarin or DOAC.

Methods: The Vascular Quality Initiative infra-inguinal bypass database was queried for all patients who underwent an infra-geniculate bypass and were anticoagulation-naive at baseline but were discharged on either warfarin or DOACs. A survival analysis was performed for patients up to 1 year to determine whether the choice of discharge anticoagulation was associated with differences between those with vein vs prosthetic conduits in overall survival, primary patency, risk of amputation, or risk of major adverse limb events (MALE). A multivariable Cox proportional hazards analysis was performed to control for differences in baseline demographic factors between the groups.

Results: During the study period (2003-2020), 57,887 patients underwent infra-geniculate bypass. Of these, 3230 (5.5%) were anticoagulated on discharge. There was a similar distribution of anticoagulation between vein (n = 1659; 51.4%) and prosthetic conduits (n = 1571; 48.6%). Thirty-two percent were discharged on DOACs, and 68.0% were discharged on warfarin. For prosthetic conduits, being discharged on a DOAC was associated with improved outcomes on univariate and multivariable analyses revealing lower risk of overall mortality (hazard ratio [HR], 0.61; 95% confidence interval [CI], 0.41-0.93; P = .021), loss of primary patency (HR, 0.70; 95% CI, 0.55-0.89; P = .003), risk of amputation (HR, 0.71; 95% CI, 0.54-0.93; P = .013), and risk of MALE (HR, 0.80; 95% CI, 0.64-1.00; P = .048). Patients with a vein bypass had improved univariate outcomes for survival and primary patency; however, with multivariable analysis, there were no significant differences in outcomes between DOAC and warfarin.

Conclusions: Anticoagulation-naive patients who underwent an infra-geniculate prosthetic bypass had higher rates of overall survival, bypass patency, amputation-free survival, and freedom from MALE when discharged on a DOAC compared with warfarin. Those with vein bypasses had similar outcomes regardless of the choice of anticoagulation.

Keywords: Anticoagulation; Direct-acting oral anticoagulants; Lower extremity; Peripheral arterial disease; Prosthetic bypass; Vein bypass; Warfarin.