Observations on the Efficacy and Safety of FRED Jr Flow Diverter for the Treatment of Intracranial Unruptured Distal Aneurysms: A Single-Center Experience.

BACKGROUND AND PURPOSE: Large-scale data on FRED Jr flow diversion for aneurysms in distal M2/M3 MCA and A2/A3 anterior cerebral artery (ACA) segments are limited. This study assessed the safety and efficacy of FRED Jr for these unruptured aneurysms, focusing on outcomes of covered vessels and identifying predictors of incomplete occlusion.

MATERIALS AND METHODS: We retrospectively reviewed 56 consecutive patients with 56 unruptured distal MCA/ACA aneurysms (mean size 3.60 mm) treated with FRED Jr. End points included aneurysm occlusion (O'Kelly-Marotta scale), clinical outcomes (mRS), and in-stent stenosis. Multivariable logistic regression was used to identify predictors of incomplete occlusion.

RESULTS: Device deployment was 100% successful, with optimal immediate apposition in 82.1%. Intraprocedural thrombosis occurred in 3 patients (5.4%), all resolving without neurologic deficits. At follow-up, 10 patients (17.8%) experienced asymptomatic (mRS = 0) adverse imaging findings, including mild-moderate in-stent stenosis (n=7) and jailed branches occlusion (n=3). Complete/near-complete occlusion rates were 73.2% at 6 months and 85.7% at 12 months. Independent predictors of incomplete occlusion were jailed branches crossing the aneurysm neck (OR = 5.5; 95% CI, 1.4-54.3; P = .02) and incomplete stent apposition (ISA; OR = 9.6; 95% CI, 2.5-60.8; P = .002).

CONCLUSIONS: FRED Jr for distal MCA/ACA, aneurysms demonstrates high technical success and favorable occlusion rates with an acceptable safety profile. However, asymptomatic in-stent stenosis or branch occlusion occurred in 17.8% of cases. ISA and the presence of jailed branches at the aneurysm neck are substantial independent risk factors for treatment failure, highlighting the need for meticulous procedural planning.