Objective: To compare the early and midterm outcomes of left subclavian artery revascularization during thoracic endovascular aortic repair (TEVAR) following carotid subclavian bypass/transposition (CSB) vs. fenestrated repair when landing in zone 1/2. Propensity score matching (PSM) was applied to adjust for baseline differences.

Methods: DEbranching versus FENestrated Repair for Left SubClavian Artery REvascularisation (DEFENCE) was a retrospective, international multicentre observational study conducted between January 2019 and July 2023 on consecutive patients who underwent open debranching or fenestration of the left subclavian artery before TEVAR for various aortic arch and descending aortic pathologies. PSM (68 pairs) was performed using logistic regression. Primary endpoints included technical success and 30-day outcomes. Secondary endpoints included re-intervention, death, and aortic related complications at 12, 24, and 36 months.

Results: 275 patients were included (198 CSB-TEVAR and 77 FTEVAR). Before PSM, statistically significant differences existed in patient demographics and the distribution of aortic pathology. In the matched cohort, CSB-TEVAR demonstrated higher overall re-intervention rates (15% vs. 3%, p = .031) and aortic related re-intervention rates (15% vs. 3%, p = .031) compared with FTEVAR. No statistically significant differences were observed in overall mortality rates (7% vs. 13%, p = .40) or aortic related mortality rate (3% vs. 3%, p = 1.0). Kaplan-Meier analysis indicated a statistically significant trend towards increased late re-intervention in the CSB-TEVAR group (log rank p = .019). Cox regression revealed that carotid subclavian bypass was associated with a fivefold increased independent risk of overall and aortic related re-interventions (hazard ratio 5.185, 95% confidence interval 1.13 - 23.86, p = .035).

Conclusion: CSB-TEVAR and FTEVAR achieved high technical success, long term durability, and similar mortality rates. FTEVAR is a durable, low re-intervention alternative, while CSB-TEVAR remains a practical option in urgent cases despite its higher incidence of peri-operative and access related morbidity.