Dual antiplatelet therapy is associated with prolonged survival after lower extremity revascularization

Background: Dual antiplatelet therapy (DAPT) after coronary stenting prolongs survival by preventing both in-stent thrombosis and other cardiovascular atherothrombotic events. Patients with peripheral artery disease (PAD) typically have a heavy burden of unrevascularized coronary artery disease and also stand to benefit from increased atherothrombotic protection with DAPT. The potential benefit of DAPT compared with aspirin alone in patients with PAD is not well described. Methods: We identified all patients undergoing an initial elective lower extremity revascularization (bypass or endovascular) from 2003 to 2016 in the Vascular Quality Initiative registry discharged on aspirin or aspirin plus a thienopyridine antiplatelet agent (DAPT). We first estimated models predicting the likelihood of receiving DAPT and then used inverse probability weighting to account for baseline differences in the likelihood of receiving DAPT and compared late survival. For sensitivity analysis, we also performed Cox proportion hazard modeling on the unweighted cohorts and generated adjusted survival curves. Results: We identified 57,041 patients undergoing lower extremity revascularization (28% bypass). Of 15,985 bypasses (69% for critical limb ischemia [CLI]), 38% were discharged on DAPT. Of 41,056 endovascular interventions (39% for CLI), 69% were discharged on DAPT. Analyses using inverse probability weighting demonstrated a small survival benefit to DAPT at 1 year for bypass (93% vs 92% [P = .001]) and endovascular interventions (93% vs 92% [P = .005]) that was sustained through 5 years of follow-up (bypass, 80% vs 78% [P = .004]; endovascular, 76% vs 73%[P = .002]). When stratified by severity of PAD, DAPT had a survival benefit for patients with CLI undergoing bypass (5 years, 70% vs 66% [P = .04]) and endovascular intervention (5 years, 71% vs 67% [P = .01]) but not for patients with claudication (bypass, 89% vs 88% [P = .36]; endovascular, 87% vs 85% [P = .46]). The protective effect of DAPT was similar when using Cox proportional hazard models after bypass (hazard ratio, 0.81 [95% confidence interval, 0.72-0.90]) and endovascular intervention (hazard ratio, 0.89 [95% confidence interval, 0.83-0.95]). Conclusions: DAPT at time of discharge was associated with prolonged survival for patients with CLI undergoing lower extremity revascularization but not for those with claudication. Further research is needed to quantify the risks associated with DAPT and to identify subgroups at increased risk of thrombotic and bleeding complications to guide medical management of patients with PAD.