Background The Neuroform Atlas Stent System is an established treatment modality for unruptured anterior and posterior circulation intracranial aneurysms. Previous studies demonstrated high rates of successful aneurysm occlusion and a favorable safety profile. Location specific results are needed to guide treatment decision making. However, it is unclear whether there are specific differences in safety and efficacy outcomes between carotid and more distal anterior circulation aneurysms.

Methods The ATLAS IDE trial was a prospective, single arm, independently adjudicated, multicenter study that evaluated the safety and efficacy of the Neuroform Atlas Stent System. We compare differences in efficacy and safety outcomes of proximal internal carotid artery (ICA) versus distal and bifurcation anterior circulation aneurysms. Primary effectiveness endpoint: complete aneurysm occlusion without clinically significant stenosis or retreatment. Primary safety endpoint: rate of major ipsilateral stroke (increase in NIHSS score ≥4) or neurological death.

Results Of the 202 anterior circulation participants enrolled, 182 patients composed the modified intention to treat cohort and were included in the analysis. Proximal subgroup included 70 (38.5%) aneurysms located at the internal carotid artery (ICA) and 112 (61.5%) at the distal anterior circulation (including ICA terminus/bifurcation). Patients from proximal aneurysm subgroup were more likely to be younger (57.4 vs. 62.1, p=.03), female (85.7% vs. 65.2%, p=.006), and to have larger parent vessel diameters (p<.0001). At one-year follow-up, there were no significant differences in the primary efficacy endpoint (85.5% vs. 83.9%, p=0.78), complete aneurysm occlusion rates (88.7% vs. 87.9%, p=0.78), recanalization rates (6.5% vs. 5.4%, p=0.76), and incidence of retreatment (2.9% vs. 4.5%, p=.55) between proximal ICA aneurysms and distal aneurysms, respectively. While it appeared that the distal group had a higher complication rate, the result was not statistically significant (6.3% vs. 1.4%, p=0.14).

Conclusion Based on these findings of the ATLAS IDE trial, the Neuroform Atlas Stent System is a safe and efficacious treatment modality for unruptured anterior circulation intracranial aneurysms in both proximal and distal, bifurcation aneurysms. Additional, studies are needed to assess complication rates in larger populations. This may have important implications for the selection of treatment modalities for intracranial aneurysms.

Disclosures R. Hanel*: 1; C; NIH, Interline Endowment, Microvention, Stryker, NX. 2; C; Medtronic, Balt, Stryker, Q’Apel Medical, Inc, Codman Neuro (J&J), Cerenovus, Microvention, Imperative Care, Inc, Phenox, Inc, Rapid Medical. 4; C; InNeuroCo, Cerebrotech, eLum, Endostream, Three Rivers Medical, Inc, Scientia, RisT, Blink TBI, Corindus. G. M. Cortez*: None. B. T. Jankowitz: 2; C; Stryker, Medtronic. E. Sauvageau: 3; C; Stryker. A. Aghaebrahim: None. E. Lin: None. A. P. Jadhav: None. B. Gross: 2; C; Medtronic, Microvention. A. Khaldi: None. R. G. Gupta: 2; C; Cerenovus. D. Frei: 2; C; Stryker, Siemens, Penumbra, Philips, Genetech, Viz.AI. D. Loy: None. L. Lyn Price: 5; C; Stryker Neurovascular. S. W. Hetts: 2; C; Microvention Terumo. 6; C; Stryker. O. O. Zaidat: None.