andated when the risk of rupture is low and interventional treatment is offered to patients at high risk of rupture. Rupture risk is driven by aneurysm diameter and growth rate. Aneurysms with diameter greater than 55 mm and/or growth rate greater than 1 cm per year are at high risk of rupture. Open surgery and endovascular treatment are the two types of interventions. Open repair consists in replacing the aneurysmal part of the aorta using a synthetic fabric prosthesis after the abdomen has been opened and the aorta clamped. This invasive procedure is associated with a 3-10% post-operative mortality. Endovascular repair (EVAR) consists in excluding the aneurysm sac by inserting a self-expanding prosthesis (called stent-graft) through very small groin incisions, without abdominal opening nor aortic clamping. This minimally invasive procedure is associated with a significantly reduced post-operative mortality (around 1%) . However, hostile proximal neck anatomy including high angulation is associated with higher rates of type IA endoleak, reintervention and long-term mortality . For this reason, a conformable design of the Excluder stent-graft has been engineered with initial satisfactory results in patients with highly angulated or short necks . However, these satisfactory results have been obtained in carefully selected patients from experienced centers and a tool demonstrating adequate apposition of the Gore ACS is lacking. Study Device Description Numerical simulation has been used successfully to predict stent-graft behavior during FEVAR . Preliminary studies have also demonstrated to applicability of the technology to standard infrarenal devices , including in the setting of very tortuous anatomies9 . The potential of numerical simulation to predict stent-graft apposition of Gore ACS in highly angulated necks appears very promising to enhance patient selection.

Inclusion Criteria:

The patient:

1. Is age ≥18 at the time of inclusion.
2. Underwent EVAR with ACS Gore Excluder
3. AAA proximal neck angulation superior to 60 degrees
4. Pre-op CT and post-operative/follow-up CT available

Exclusion Criteria:

1. Slice thickness of Pre-op or post-op / follow-up CT superior to 2mm.
2. Non-injected or poorly injected pre-operative CT-scan precluding technical feasibility of the aortic digital twin
3. Absence of post-operative or follow-up CT-scan
4. Patient refusal of his personal information/medical data to be used in the context of the study

Patients who underwent EVAR with ACS Gore excluder. Only patients with proximal neck angulation superior to 60 degrees will be considered.