Abstract 9499: Clinical Outcomes With Initial Thoracic Endovascular Aortic Repair versus Initial Medical Therapy for Acute Uncomplicated Type B Aortic Dissection in the United States

Introduction: Thoracic endovascular aortic repair (TEVAR) has increasingly been used for uncomplicated type B aortic dissection (uTBAD) despite limited supporting data. We compared outcomes after a strategy of initial TEVAR vs. initial medical therapy in patients with uTBAD. Methods: Index acute uTBAD admissions from 2011-2018 were identified using 100% Medicare inpatient claims. Initial TEVAR was defined as TEVAR within 30 days of admission. Complicated and non-acute TBAD were excluded. Outcomes included survival, cardiovascular hospitalizations, aorta-related and repeat aorta-related hospitalizations, and aortic interventions. Propensity score inverse probability weighting (IPW) was used to reduce the effects of treatment selection bias in the data. The primary analyses were landmarked at 30 days to avoid survival time bias; a sensitivity analysis used TEVAR status as a time-dependent variable to account for deaths in the first 30 days. Results: Of 7,105 patients with eligible index admissions for acute uTBAD, 1,140 (16.0%) underwent initial TEVAR. Receipt of initial TEVAR was significant associated with geographic region, non-Medicaid dual eligibility, and institutional TEVAR volume as well as certain comorbidities. After IPW, mortality was similar for the two strategies out to 5 years (HR 0.95, 95% CI 0.85 to 1.06), while aorta related hospitalizations were modestly increased with the TEVAR strategy (HR 1.12, 95% CI 0.99 to 1.27). In the sensitivity analysis including deaths within the first 30 days, initial TEVAR was associated with lower mortality over a period of 1 year (aHR 0.86, 95%CI 0.74-0.997, p=.045), 2 years (aHR 0.85, 95%CI 0.75-0.96, p=.01), and 5 years (aHR 0.87, 95%CI 0.79-0.97, p=.008). Conclusions: We found that a significant minority of uTBAD patients undergo initial TEVAR, which may be associated with lower risk of mortality when deaths within the first 30 days are included. These outcomes, and the reasons why some patients receive initial TEVAR while others do not, remain incompletely characterized. These findings, along with factors related to anatomy, peri-procedural complications, adequacy of medical therapy, patient preferences, and cost effectiveness, need to be assessed in a prospective trial in the US population.