Treatment of Unruptured Distal Anterior Circulation Aneurysms with Flow-Diverter Stents: A Meta-Analysis.

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The safety and efficacy of flow diversion among distal anterior circulation aneurysms must be proved. Our aim was to analyze the outcomes after flow diversion among MCA, anterior communicating artery, and distal anterior cerebral artery aneurysms. A systematic search of 3 databases was performed for studies published from 2005 to 2018. According to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we included studies reporting flow diversion of distal anterior circulation aneurysms. Random-effects meta-analysis was used to pool aneurysm occlusion and complication rates. From the individual patient data, univariate and multivariate analyses were used to test predictors of occlusion and complications. We included 27 studies (484 aneurysms). The long-term adequate occlusion rate (O'Kelly-Marotta scale, C-D) was 82.7% (295/364; 95% CI, 77.4%-87.9%; I2 = 52%). Treatment-related complications were 12.5% (63/410; 95% CI, 9%-16%%; I2 = 18.8%), with 5.4% (29/418; 95% CI, 3.2%-7.5%; I2 = 0%) morbidity. MCA location was an independent factor associated with lower occlusion (OR = 0.5, P = .03) and higher complication rates (OR = 1.8, P = .02), compared with anterior communicating artery and distal anterior cerebral artery aneurysms. The Pipeline Embolization Device (versus other stents) gave better occlusion rates (OR = 2.6, P = .002), whereas large/giant aneurysms were associated with higher odds of complications (OR = 2.2, P = .03). The rates of occlusion and narrowing of arteries covered by flow-diverter stents were 6.3% (29/283; 95% CI, 3.5%-9.1%; I2 = 4.2%) and 23.8% (69/283; 95% CI, 15.7%-32%; I2 = 80%), respectively. Symptoms related to occlusion and narrowing of the jailed arteries were 3.5% (6/269; 95% CI, 1.1%-5%; I2 = 0%) and 3% (6/245; 95% CI, 1%-4%; I2 = 0%), respectively. We reviewed small and retrospective series. Flow diversion among distal anterior circulation aneurysms is effective, leading to adequate aneurysm occlusion in 83% of cases. However, this strategy has some limitations among MCA and larger lesions, especially related to the higher rate of complications. Compared with the other devices, the Pipeline Embolization Device seems to be associated with a higher occlusion rate.