Bridging Stent Graft Durability after Branched Endovascular Repair: Geometric Remodeling and Predictors of Target Vessel Instability

Background: Bridging stent graft (BSG) durability is a major determinant of success after branched endovascular aneurysm repair (BEVAR), yet longitudinal data describing time-dependent BSG geometric remodeling and its relationship with target vessel instability (TVI) remain limited. Methods: A single-center retrospective analysis was conducted of consecutive patients undergoing BEVAR for thoracoabdominal aneurysms (January 2018 to December 2024) in whom a self-expanding covered stent (Covera Plus) was used as BSG. The primary end point was freedom from TVI. Computed tomography angiography (CTA) measurements (branch total length [TL], branch vertical length, tortuosity index (TI), target-vessel sealing (TVS), endstent angle [ESA]) were analyzed for associations with TVI and for longitudinal trajectories; receiver operating characteristic analyses assessed percent-change thresholds between serial CTAs. Results: The cohort included 52 patients (mean age 74 years) and 208 target vessels; technical success was achieved in 200/208 target vessels (96.1%). Median follow-up was 34 months; 9 deaths occurred (17.3%), none aortic-related. Thirteen target-vessel reinterventions were performed (6.5%), predominantly in renal arteries; no BSG migration was detected. Freedom from TVI at 60 months was 93.5%. Greater BSG TL and higher tortuosity were associated with an increased risk of TVI, whereas longer TVS length was protective. Longitudinal analysis showed a progressive reduction in TVS and TI, along with an increase in ESA over time. These changes were more pronounced in renal arteries for TI (interaction P = 0.011) and ESA (interaction P = 0.004), whereas no significant difference was observed for TVS between vessel types (interaction P = 0.748). Percent-change thresholds between CTAs (mean interval 16.5 months) predicted TVI: target-vessel sealing decrease >= 9.3%, TI increase >= 10.1%, and end-stent angle increase >= 26.7%. Conclusion: In this single-center BEVAR using a uniform self-expanding bridging platform, midterm branch durability was favorable, with renal branches remaining the most vulnerable. Both postimplant geometry and its time-dependent evolution were associated with TVI, supporting surveillance strategies that incorporate standardized serial CTA-based geometric assessment and dynamic change thresholds to identify early unfavorable remodeling.