Endovascular Repair of an Abdominal Aortic Aneurysm with an S-Shaped and Severely Tortuous Proximal Neck: A Case Report.

Background: Endovascular aneurysm repair (EVAR) is a minimally invasive treatment for abdominal aortic aneurysm (AAA). However, severely angulated or S-shaped "hostile" proximal necks remain challenging, increasing the risk of type IA endoleak and early procedural failure. Morphological indices such as neck angles, tortuosity index (TI), and angle-length index (ALI) have been proposed to predict EVAR outcomes. However, their measurement in clinical practice remains limited, particularly in highly deformed necks, and they do not assess axial torsion. Case Presentation: We report a 65-year-old male with a 73 mm infrarenal AAA and a 39 mm S-shaped proximal neck (suprarenal angle 105°, infrarenal angle 111°, TI ≈1.42), outside the recommended IFU thresholds. EVAR was performed using the Endurant™ II system (Medtronic). An in-traoperative type IA endoleak occurred and was successfully treated with an addi-tional proximal cuff and ballooning, achieving complete sealing. The patient recovered uneventfully and was discharged in stable condition. Follow-up CTA at 24 months demonstrated a stable stent graft, no endoleak, and unchanged aneurysm diameter. Conclusion: This case report demonstrates that durable outcomes can be achieved with EVAR even in the setting of a "hostile neck" with severe S-shaped morphology and torsion. Experience from this case suggests that comprehensive morphological assess-ment-including novel indices for torsion-combined with timely intraoperative management of type IA endoleak using a proximal cuff is critical for long-term success. This underscores the importance of improving current risk models to more accurately incorporate complex 3D deformities in preoperative planning.