Flow diversion for posterior circulation intracranial aneurysms: A systematic review and meta-analysis

Background: Posterior circulation (PC) aneurysms are associated with a higher risk of rupture. Flow diverters (FDs) are widely used for carotid intracranial aneurysms, but their role in PC aneurysms is less established. This meta-analysis examines the available literature on the safety and effectiveness of FDs for PC aneurysms. Method: We conducted a systematic search from database inception until October 2024. The primary effectiveness outcome was complete occlusion rate defined by the Raymond-Roy and/or O'Kelly-Marotta scales. Primary safety outcomes included thromboembolic event rates following implantation. Secondary outcomes included procedure-related mortality, good functional outcome (GFO), and retreatment. Pool estimates were calculated using a random-effect model. Subgroup analysis based on morphology and study design was also conducted. Results: A total of 42 studies met our inclusion criteria. A total of 1698 patients were treated with FDs for 1760 PC aneurysms. Among these cases, 47.6% were in the vertebral artery. Our pooled overall analysis of complete occlusion rates was 72.73% (P<0.0001; I²=67.2%), and the pooled thromboembolic events rate following implantation was 11.70% (P<0.0046; I²=70.5%). Additionally, the pooled mortality rate was 8.07% (P<0.0001; I²=61.5%), the retreatment rate was 6.59% (P<0.4260; I²=1%), and the pooled GFO rate was 83.99% (P<0.0001; I²=76%). Subgroup analysis revealed that fusiform-dolichoectatic had a complete occlusion rate of 48.29% (P<0.3223; I²=11.7%). Conclusion: FDs for PC aneurysms achieve generally adequate occlusion rates, except in dolichoectatic-fusiform subtypes. Despite achieving adequate occlusion rates, FD use was associated with higher thromboembolic events, mortality, and retreatment rates, which necessitates careful patient selection.