Early Aneurysm Occlusion Outcomes After Endovascular Treatment: A Descriptive Single-Center Cohort Evaluation

Background: Early residual or recurrent aneurysm filling remains an important limitation after endovascular treatment of intracranial aneurysms, particularly in large and complex lesions. This study descriptively evaluated 6-month early residual or recurrent filling after coil embolization, stent-assisted coiling, flow-diverting stents, and the Woven EndoBridge (WEB) device in a single-center cohort. Methods: We retrospectively analyzed 151 patients with 161 intracranial aneurysms treated between January 2019 and July 2023. Follow-up imaging at approximately 6 months was performed using computed tomography angiography or magnetic resonance angiography, with digital subtraction angiography when residual filling was suspected. Aneurysm occlusion was evaluated using the Raymond–Roy Occlusion Classification. Clinical, morphological, anatomical, and treatment-related variables associated with early residual or recurrent aneurysm filling were analyzed. Results: Complete occlusion was achieved in 149 aneurysms (92.5%), whereas early residual or recurrent filling occurred in 12 aneurysms (7.5%). Residual or recurrent filling was observed in 4/35 aneurysms treated with coil embolization (11.4%), 1/58 treated with flow-diverting stents (1.7%), 7/60 treated with the WEB device (11.7%), and none of the 8 aneurysms treated with stent-assisted coiling; overall rates did not differ significantly among treatment modalities (p = 0.104). Aneurysm height > 10 mm was significantly associated with early residual or recurrent filling (p = 0.005), and mean aneurysm height was greater in aneurysms with residual or recurrent filling than in completely occluded aneurysms (p = 0.048). In the ICA subgroup, residual or recurrent filling was more frequent after WEB treatment than after other endovascular modalities (p = 0.019). This subgroup signal was based on sparse observations. Conclusions: Aneurysm height > 10 mm was significantly associated with early residual or recurrent aneurysm filling. No statistically significant difference in early residual or recurrent filling was detected among treatment groups. Given the retrospective design, non-random treatment allocation, heterogeneous aneurysm phenotypes, and non-uniform imaging follow-up, these data should be interpreted as a descriptive institutional experience rather than evidence of comparative superiority or equivalence. The ICA subgroup finding is preliminary and hypothesis-generating.