Abstract WP213: Association Between Thoracic Aorta Surgery and Long Term Risk of Stroke in Adults

Introduction: Thoracic aorta surgery carries a risk of perioperative stroke, but the long-term incidence of stroke after the perioperative period in these patients remains unclear. We therefore assessed the long-term risk of stroke in patients who underwent thoracic aorta repair. Methods: We performed a retrospective cohort study using 2008-2015 claims data from a nationally representative 5% sample of Medicare beneficiaries. Our exposure of interest was thoracic aorta surgery, defined using ICD-9-CM hospital procedure codes for endovascular graft implantation (39.73) or surgical resection and replacement (38.45). Our primary outcome was ischemic stroke, defined using previously validated ICD-9-CM diagnosis codes. Patients with stroke during the index surgical hospitalization were excluded, since our focus was on long-term stroke risk after the perioperative period . Cox proportional hazards analysis was used to examine the association between thoracic aorta surgery and stroke risk after adjustment for demographics and vascular risk factors. Given a clear violation of the proportional hazards assumption, we calculated period-specific risk estimates. Results: Among 1,751,719 beneficiaries (mean age 73 ±8 years), 1,402 underwent thoracic aorta repair. During 4.6 ±2.2 years of follow-up, 62,702 patients were diagnosed with ischemic stroke. The incidence of stroke was 1.24% (95% CI, 0.93-1.66%) per year after thoracic aorta repair compared to 0.77% (95% CI, 0.76-0.78%) per year in patients without thoracic aorta surgery. In adjusted models, there was an increased risk of stroke in the first 120 days after discharge from thoracic aorta surgery (HR, 2.1; 95% CI, 1.2-3.7), but no heightened risk was seen beyond 120 days after discharge from surgery (HR, 0.7; 95% CI, 0.5-1.0). Conclusions: In a large sample of Medicare beneficiaries, thoracic aorta surgery was associated with an increased risk of ischemic stroke in the first 120 days after hospital discharge, but there was no excess risk beyond that time point.