Abstract 170: Flow Diversion for Distal Aneurysms of the Posterior Circulation: A Multicenter Retrospective Study

Introduction Flow diversion (FD) has emerged as an effective treatment option for intracranial aneurysms (IAs). However, there is limited evidence regarding its safety and efficacy specifically for distal aneurysms of the posterior circulation including posterior inferior cerebellar artery (PICA), anterior inferior cerebellar artery (AICA), superior cerebellar artery (SCA), and the P2 and P3 segment of the posterior cerebral artery (PCA). This study aimed to investigate the outcomes of FD for these aneurysms. Methods A retrospective analysis of a multicentric observational registry was performed between 2014 and 2022. Patients harboring distal aneurysms of the posterior circulation including the PICA, AICA, SCA, and PCA P2‐3 treated with FD were included. Aneurysms characteristics and outcomes were calculated for the total series and a comparison was performed between fusiform/dissecting versus saccular aneurysms. The primary outcome was complete occlusion at last imaging follow up which was defined as per the Raymond Roy occlusion scale. Additional outcomes included the retreatment rate, and thromboembolic and hemorrhagic complications Results Overall, 36 patients with 36 aneurysms were treated with FD with a median age in years of 60.0 (interquartile range [IQR]: 52.8‐65.3 years). Of those, 13 were fusiform/dissecting while 23 were saccular IAs. Complete occlusion was achieved in 78.1% for all IAs at a median follow‐up of 14.0 months (IQR: 9.3‐48.6 months). There was no significant difference in rates of complete occlusion between fusiform/dissecting (91.7%) and saccular aneurysms (70%, p=0.151). Thromboembolic and hemorrhagic complications were observed in four cases (11.1%), and retreatment was required for four IAs (11.4%). There was no significant difference in rates of thromboembolic and hemorrhagic complications, or retreatment between fusiform/dissecting and saccular IAs Conclusion This study suggests the safety and efficacy of FD for distal aneurysms of the posterior circulation. Further larger‐scale studies are warranted to confirm these findings and to explore the long‐term safety and efficacy of FD in this specific aneurysm population.