Flow Diverter Stents for Recurrent Intracranial Aneurysms after Stent-Assisted Coil Embolization: Safety, Efficacy, and Technical Considerations-A Comprehensive Review.

Objective: Stent-assisted coil (SAC) embolization reduces intracranial aneurysm recurrence compared with coiling alone; however, post-SAC recanalization still occurs and presents a significant therapeutic challenge. This review evaluates SAC outcomes, predictors of recanalization, and the evidence for flow diverter stent (FDS) treatment of recurrent aneurysms following SAC. Methods: A systematic literature search was performed using PubMed/MEDLINE (January 2000-March 2026) with the terms "intracranial aneurysm," "stent-assisted coiling," "flow diverter," "recanalization," and "retreatment." Studies reporting quantitative angiographic or clinical outcomes were included. Case reports, non-English publications, and non-PubMed-indexed sources were excluded. Results: Coiling alone carries a recanalization rate of 20%-33% and retreatment rate of 10%-15%. SAC significantly reduces recurrence (recurrence risk 0.43; 95% confidence interval 0.33-0.53), albeit with a higher procedural hemorrhagic risk. Bifurcation aneurysm location (odds ratio [OR] 9.02; p = 0.001) and convex parent artery curvature (OR 3.68; p = 0.025) were the dominant independent predictors of SAC recanalization; packing density alone was not independently significant. For post-SAC recurrent aneurysms, FDS achieves complete occlusion in 38%-94% across published series, with progressive improvement over time. The largest multicenter study (N = 118, 22 institutions) demonstrated a technical success rate of 98.3%, complete occlusion of 62.5%, combined complete-or-near-complete occlusion of 87.5%, major complication rate of 3.4%, and favorable functional outcome (modified Rankin Scale 0-2) in 95.1%. Wider aneurysm neck diameter was the sole independent predictor of incomplete FDS occlusion (adjusted OR 1.23/mm; p = 0.044). Conclusion: Based on the available retrospective evidence, FDS treatment represents a technically feasible salvage option for post-SAC recurrent aneurysms with an acceptable complication profile in experienced centers; however, conclusions about superiority over alternative retreatment strategies and its role as the preferred modality are premature in the absence of prospective comparative data. Meticulous microwire navigation, appropriate FDS sizing, and rigorous dual antiplatelet therapy management may be essential for optimal outcomes.