Delayed deformation of the Neuroform Atlas Stent during follow-up: Observational findings and clinical implications

The Neuroform Atlas Stent (NAS) has become one of the most widely used stents for stent-assisted coil embolization of wide-necked intracranial aneurysms, owing to its low-profile design, flexible deliverability, and compatibility with 0.017-inch microcatheters. However, data on its long-term durability are limited. The purpose of this study is to evaluate the incidence, angiographic features, and clinical significance of NAS deformation or crumpling that occurs during the follow-up period.

We retrospectively reviewed 174 patients with unruptured intracranial aneurysms who underwent NAS-assisted coiling from March 2018 to December 2024, all of whom had follow-up digital subtraction angiography. Stent deformation or crumpling was defined as a noticeable change in the position or spacing of the stent markers on unsubtracted images between the immediate post-procedural and follow-up examinations.

Significant NAS deformation was observed in 7 of 174 patients (4.02 %). All aneurysms were located in the anterior circulation, with the most common site being the ophthalmic segment of the internal carotid artery. The mean aneurysm dome and neck sizes were 4.1 mm and 3.3 mm, respectively. Despite the marker changes, all aneurysms remained stable or showed progressive occlusion. In-stent stenosis of more than 30 % occurred in one patient. Antiplatelet response was adequate in almost all patients, with only one patient showing a high P2Y12 reaction unit value.

Stent deformation or crumpling of the NAS can occur as a rare, delayed finding. While this observational study found that this mechanical change did not compromise short-term aneurysm occlusion, its long-term clinical implications remain unclear. The thin profile of the NAS may contribute to a degree of vulnerability within the intracranial circulation until sufficient endothelialization is achieved. Long-term follow-up is necessary to clarify the clinical implications of this crumpling phenomenon.