Determination of Optimal and Safest Proximal Sealing Length During Thoracic Endovascular Aortic Repair.

Objective: To determine the optimal and safest proximal sealing length (PSL) during thoracic endovascular aortic repair (TEVAR), depending on anatomical aortic arch types and proximal landing zones (LZs).

Methods: This was a single centre retrospective observational study of consecutive TEVAR patients (2008-2020). All aortic pathologies requiring Ishimaru landing zone (LZ) 0 - 3 were included; results were stratified by aortic arch type. The PSL was measured as the length of complete aortic wall to endograft apposition at the level of the proximal neck. The primary endpoint was proximal failure (type 1A endoleak, endograft migration, or re-intervention requiring proximal graft extension). Freedom from proximal failure was estimated with Kaplan-Meier curves. An "optimal" sealing length (PSL cutoff maximising sensitivity + specificity for proximal failure) and "safest length" (PSL cutoff determining ≥ 90% sensitivity) were identified using receiver operating characteristic curve analysis.

Results: One hundred and forty patients received TEVAR; mean ± standard deviation PSL was 29 ± 9 mm. Freedom from proximal endograft failure at five years (median 31 months) was 82.4% (95% confidence interval [CI] 72 - 95); the shorter the PSL, the greater was the risk of failure (hazard ratio 0.90, 95% CI 0.84 - 0.97; p = .004). Overall optimal and safest PSL were 25 mm (sensitivity 78%, specificity 66%) and 30 mm (sensitivity 92%, specificity 30%), respectively. In type I arch, the optimal PSL was 22 mm (sensitivity 50%, specificity 87%). In type II, the optimal PSL was 25 mm (sensitivity 89%, specificity 59%) overall and 27 mm for type II/LZ 2 - 3 (sensitivity 31%, specificity 68%). For type III, the optimal PSL was 27 mm (sensitivity 80%, specificity 87%); the safest was 30 mm (sensitivity 100%, specificity 61%) In type III/LZ 2 - 3, the optimal PSL was 27 mm (sensitivity 31%, specificity 68%) and safest was 30 mm (sensitivity 100%, specificity 55%).

Conclusion: A 20 mm PSL may be acceptable only for type I arches. For types II/III, that represent the majority of cases, a 25 - 30 mm PSL may be required for a safe and durable TEVAR.