Effects Of Dual Antiplatelet Therapy On Graft Patency After Lower Extremity Bypass

Abstract [from journal]

Objective: Current guidelines recommend single agent antiplatelet therapy for patients with symptomatic peripheral arterial disease and for consideration of dual antiplatelet therapy (DAPT) after surgical revascularization. The objective of this study was both to explore prescribing patterns of single versus dual antiplatelet therapy after lower extremity bypass surgery, and to investigate the effects of antiplatelet therapy on bypass graft patency.

Methods: A retrospective analysis of prospectively collected non-emergent infrainguinal lower extremity bypass operations entered in the national Vascular Quality Initiative (2003-2018) with captured long-term follow-up was performed. Patients discharged on aspirin monotherapy or DAPT were identified. Linear regression investigated temporal trends in antiplatelet utilization. Multivariable Cox regression investigated predictors of primary, primary-assisted, and secondary patency.

Results: Of the 13,020 patients investigated, 52.2% were discharged on aspirin monotherapy, and 47.8% on DAPT. The proportion of patients discharged on DAPT increased from 10.6% in 2003 to 60.6% in 2018 (P<0.001). The DAPT cohort was younger, had higher rates of medical (HTN, diabetes, CHF, COPD) and atherosclerotic comorbidities (CAD, prior CABG or PCI, prior lower extremity intervention), and had higher risk bypass procedures (more distal targets, prior inflow bypass procedure, prosthetic conduit utilization). Multivariable cox regression analysis did not show any difference between the DAPT and aspirin cohorts in primary patency (HR 0.98, 95% CI 0.88-1.10, P=0.78), primary assisted patency (HR 0.93, 95% CI 0.80-1.07, P=0.30) or secondary patency (HR 0.88, 95% CI 0.74-1.06, P=0.18). On subgroup analysis based on bypass conduit, DAPT was found to have a protective effect on patency only in the prosthetic bypass cohort: primary patency (HR 0.81, 95% CI 0.66-1.00, P=0.05), primary assisted patency (HR 0.74, 95% CI 0.58-0.94, P=0.01), and secondary patency (HR 0.60, 95% CI 0.44-0.82, P<.001). No patency differences were observed on adjusted subgroup analysis for the other bypass conduits.

Conclusions: A significant and increasing proportion of patients are discharged on dual antiplatelet therapy after lower extremity bypass revascularization. These patients represent a higher risk cohort with more medical comorbidities and higher risk bypass features. After controlling for these differences, DAPT therapy had no beneficial effect on overall bypass graft patency or major adverse limb events. However, on subgroup analysis, DAPT was associated with improved bypass graft patency in patients receiving prosthetic bypass conduits. Further study is warranted to investigate optimal duration of DAPT therapy and its possible bleeding complications in prosthetic bypass patients.