Effects of Dual Antiplatelet Therapy on Graft Patency After Lower Extremity Bypass

Abstract

The objective of this study was to explore prescribing patterns of single vs dual antiplatelet therapy (DAPT) after lower extremity bypass surgery and to investigate the effects of antiplatelet therapy on bypass graft patency. A retrospective review of nonemergent infrainguinal lower extremity bypass operations entered in the national Vascular Quality Initiative (2003-2018) was performed. Patients discharged on aspirin monotherapy or DAPT were identified. Multivariable Cox regression investigated predictors of primary, primary assisted, and secondary patency. 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 < .001). The DAPT cohort was younger, had higher rates of medical (hypertension, diabetes, congestive heart failure, chronic obstructive pulmonary disease) and atherosclerotic (coronary artery disease, prior coronary artery bypass graft, prior lower extremity intervention) comorbidities, and had higher risk bypass procedures (more distal targets, prior inflow bypass procedure, prosthetic conduit use). Multivariable Cox regression analysis did not show any difference between the DAPT and aspirin cohorts in primary patency (hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.88-1.10; P = .78), primary assisted patency (HR, 0.93; 95% CI, 0.80-1.07; P = .30), or secondary patency (HR, 0.88; 95% CI, 0.74-1.06; P = .18). On subgroup analysis delineated by 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 = .05), primary assisted patency (HR, 0.74; 95% CI, 0.58-0.94; P = .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 conduits (Fig). A significant and increasing proportion of patients are discharged on DAPT 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.