IFT12 - Geometrical Analysis on Flared Section of Stainless-steel Bridging Stent-grafts for Fenestrated Endovascular Aneurysm Repair

Objectives: Our study aims to identify new predictive factors of target vessel instability (TVI) by performing a geometrical analysis on stainless-steel bridging stent-grafts (BSGs) employed in Fenestrated Endovascular Aortic Aneurysm Repair (FEVAR), focusing on their flared portion.

Methods: Data on patients undergoing FEVAR for thoraco-abdominal and complex abdominal aortic aneurysms between 2010 and 2021 at our Vascular and Endovascular unit were collected. A vessel-focused retrospective analysis was conducted on the preoperative computed tomography angiography (CTA) and the postoperative CTA performed at 30 days, excluding cases whose geometrical evaluation could not be performed because of non-adequate CTA, and cases with BSG not composed of stainless steel. Geometrical data included flaring angles "α and β" (measured respectively as the angles between the upper or the lower flared part of the BSG and the line perpendicular to the one passing through the upper and lower markers of the fenestration) and misalignment between fenestrations. Decision trees identified cut-off values of "α and β" angles based on TVI as the response variable. Primary endpoints were technical success, freedom from TVI, and freedom from reintervention. The role of geometrical data in influencing TVI was determined with Cox proportional hazard models.

Results: 38 patients (119 arteries) were included in the vessel-focused analysis. Technical success of interventions was 82%, with 93% assisted technical success. At 30-days, three occlusions (2.5%, all in the renal arteries subgroup) and eight type IIIc endoleaks occurred (6.7%, 3 visceral arteries and 5 renal arteries). Freedom from TVI was 90% both at 12 and 24 months. BSG-related freedom from reintervention at 12 and 24 months were 99% and 93%, respectively. Flaring angles ("β" < 25° associated with "α" < 16°; HR 4.97, 95% CI 1.42 - 17.32, p= .011) and BSG misalignment (HR 6.03, 95% CI 1.58 - 22.96, p= .008) were identified on multivariate models as independent predictive factors of TVI.

Conclusions: Based on our preliminary results, BSGs’ flared section angles and BSG misalignment could be predictive factors of target vessel instability. Therefore, an intraoperative and postoperative evaluation of the BSG flared portion could have a role in anticipating and thus preventing vessel-related complications after FEVAR. Further analyses on a larger number of patients and a longer follow-up are needed to draw firm conclusions.