Efficacy and Safety of Flow Diversion for Distal Anterior Cerebral Aneurysms: A Systematic Review and Proportional Meta-Analysis

Flow diverters (FDs) are increasingly used off-label for the treatment of distal anterior cerebral artery aneurysms (DACAAs), located at or beyond the A2 segment of the anterior cerebral artery (ACA). However, data on safety and efficacy remain limited. To evaluate the safety and efficacy of FDs for the treatment of DACAAs through a systematic review and meta-analysis. PubMed, Scopus, and Web of Science were systematically searched according to PRISMA guidelines. Studies were eligible if they reported on ≥5 patients treated with FDs for DACAAs and provided angiographic and clinical outcome data. Efficacy outcomes included adequate and complete aneurysm occlusion rates and retreatment rates. Safety outcomes included good functional outcome (mRS 0-2), procedure-related morbidity and mortality, procedure-related complications, in-stent stenosis, and covered branch occlusion. Pooled estimates with 95% confidence intervals (CIs) were calculated using a random-effects model. Eleven retrospective studies comprising 326 patients (71% female; mean age, 59.4 ± 4.4 years) with 328 DACAAs were included. Most aneurysms were unruptured (95.7%) and located in the A2 or A2-A3 segments (89%). Adequate and complete occlusion at last follow-up were 89% (95% CI, 82-96) and 77% (95% CI, 69-85), respectively. The retreatment rate was 1% (95% CI, 0- 3). Good functional outcome was reported in 97% (95% CI, 95-100). Procedure-related complications occurred in 7% (95% CI, 1-12), resulting in 1% morbidity (95% CI, 0-3) and no procedure-related deaths. In-stent stenosis and covered branch occlusion were observed in 4% (95% CI, 0-10) and 10% (95% CI, 6-13), respectively. Clinically symptomatic covered branch occlusion was rare (1.1%), possibly reflecting the adequacy of collateral circulation in distal ACA territory. The analysis is based on retrospective studies that lacked centralized adjudication of angiographic outcomes, potentially introducing methodological biases intrinsic to such study designs, including selection bias, confounding, and publication bias. FDs appear to be a safe and effective treatment option for DACAAs, with high rates of occlusion and favorable clinical outcomes, and low rates of retreatment and procedure-related complications. ACA＝ anterior cerebral artery; DACAAs＝ distal anterior cerebral artery aneurysms; FDs＝ flow diverters.