Abstract 67: Effects of Single vs Dual Antiplatelet Therapy on Long Term Stroke and Death After Carotid Endarterectomy

Introduction: Current evidence suggests that dual antiplatelet therapy (DAPT) reduces perioperative stroke, but increases bleeding after carotid endarterectomy (CEA). The long term effects of antiplatelet therapy after CEA have yet to be studied. Methods: A retrospective review of patients undergoing CEA in the national Vascular Quality Initiative database (2003-2018) was performed. Based on antiplatelet regimen at discharge, patients were propensity score matched on aspirin monotherapy vs. DAPT. Multivariable logistic regression and Kaplan-Meier analyses were used to investigate the long term effects of antiplatelet regimen on mortality and stroke/TIA. Results: Of the 72,122 patients undergoing CEA, 64.6% were discharged on aspirin, and 35.4% on DAPT. The DAPT group had higher frequencies of comorbidities (COPD, HTN, CHF, smoking, diabetes) as well as atherosclerotic diseases (PAD, CAD, prior PCI, prior CABG). After propensity score matching, two groups of 8,722 patients with comparable comorbidities were formed. While unmatched Kaplan-Meier analysis showed the DAPT cohort to have higher mortality (p=0.001), this difference dissipated after matching. The resultant matched DAPT cohort did not differ from the aspirin group in one year stroke/TIA (1.7% vs. 1.6%, p=0.70), or mortality (3.1% vs. 3.3%, p=0.55). At 5 years, however, patients treated with DAPT did exhibit a mortality benefit (6.4% vs. 7.3%, p=0.02) with multivariable logistic regression identifying DAPT as an independent predictor of reduced mortality (OR 0.94, 95% CI 0.88-0.99, p=0.04). Conclusions: Patients discharged on DAPT after CEA represent a significantly different cohort than those discharged on aspirin monotherapy. After propensity score matching, there was no difference at one year stroke/TIA or mortality outcomes, but DAPT was found to be protective against long-term mortality. Further study is warranted to investigate this finding.