Geometrical Analysis of Target Vessel Instability After FEVAR With Anaconda Stent-Graft System.

Introduction
Fenestrated endovascular aneurysm repair (FEVAR) has emerged as a standard treatment for complex abdominal and thoracoabdominal aortic aneurysms (CAAAs/TAAAs), yet target vessel instability (TVI) remains a concern. This study evaluates mid-term outcomes and anatomical predictors of TVI following FEVAR using the Anaconda custom-made fenestrated stent-graft system (Terumo Aortic, Inchinnan, Scotland, UK).Methods
A retrospective single-center study included all consecutive patients treated with FEVAR using Anaconda stent-graft between September 2013 and December 2023. Preoperative and postoperative vessel geometry was assessed using Aquarius iNtuition software (TeraRecon, Foster City, CA). Primary endpoints were TVI (occlusion, stenosis, type I/III endoleak, or re-intervention) and freedom from re-intervention at 12 months. Secondary endpoints were intraoperative technical success and 30-day major adverse events (MAEs) rate.Results
A total of 101 patients with 359 target vessels were analyzed. Technical success was 97%. The 30-day MAE rate was 21.7%, with no mortality. Target vessel instability occurred in 7.8% (4.5% type IIIc endoleak, 1.4% stenosis, and 1.9% type Ic endoleak) during a median follow-up of 36 months (interquartile range [IQR]=22-55 months). Multivariate analysis identified increased sealing length (odds ratio [OR]=1.080, 95% confidence interval [CI]: 1.002, 1.164, p=0.044) and intra-aortic stent protrusion≥7 mm (OR=1.406, 95% CI: 1.067, 1.852, p=0.015) as independent predictors of TVI in visceral vessels. In renal target vessels, protrusion ≥ 7 mm (OR=1.284, 95% CI: 1.019, 1.618, p=0.034) was significantly associated with occlusion. Cumulative incidence of TVI with death as competing risk was 3.1%, 3.6%%, and 5.9% at 1, 2, and 5 years, respectively.Conclusion
Fenestrated endovascular aneurysm repair using the Anaconda stent-graft system demonstrates high technical success and mid-term freedom from TVI. Extended intra-aortic stent protrusion and sealing length, significantly impact TVI adversely. Optimizing bridging stent geometry may reduce re-intervention rates and improve outcomes in complex aortic repairs.Clinical ImpactThis study demonstrates that fenestrated endovascular aneurysm repair using the Anaconda custom-made fenestrated stent-graft system provides high technical success and durable mid-term target vessel stability in complex aortic aneurysm repair. Importantly, it identifies modifiable anatomical predictors-excessive intra-aortic bridging stent protrusion and increased sealing length-as independent risk factors for target vessel instability. These findings shift attention from device selection alone to precise geometric optimization of bridging stents during procedural planning and deployment. For clinicians, careful control of protrusion length and sealing configuration may reduce endoleaks and re-interventions. The innovation lies in linking quantitative vessel geometry to clinical outcomes, offering actionable parameters to improve durability in FEVAR.