Comparing Flow Diversion and Stent-Assisted Coiling in Unruptured Intracranial Aneurysms: A Meta-Analysis of Head-to-Head Studies

Background: The optimal endovascular strategy for unruptured intracranial aneurysms remains debated, especially with the emergence of flow diversion (FD) as an alternative to stent-assisted coiling (SAC). While immediate occlusion benefits are observed with SAC, FD facilitates gradual vessel reconstruction with potential for superior durability long-term. Prior meta-analyses have lacked head-to-head comparisons or occlusion assessment greater than 6 months. This study provides a comprehensive evaluation of the efficacy and safety of SAC versus FD, utilizing only direct comparative studies and assessing both 6-month and 12-month occlusion rates. Methods: A systematic review of MEDLINE and Embase was conducted per PRISMA guidelines. Included studies directly compared SAC and FD for unruptured aneurysms with reported clinical and angiographic outcomes. Pooled relative risk (RR) and odds ratios (OR) were calculated using random-effects models. Sensitivity analyses excluded aneurysms >10mm and non-SAC coiling cohorts. Heterogeneity was quantified using I 2 , and publication bias was assessed via funnel plots. Satisfactory aneurysm occlusion (SAO) rates were defined as Raymond Roy grades I and II. Results: Thirteen studies comprising 1,472 patients were analyzed with a mean follow-up duration of 20.1 months (6.5–30.5). SAC and FD demonstrated comparable 6-month and 12-month SAO rates. However, FD achieved a significantly higher eventual complete occlusion (Raymond-Roy grade I) rate (RR = 0.67, 95% CI: [0.51; 0.87], p = 0.003, I 2 = 86.2%) though this was not significant when aneurysms >10mm were excluded. Recurrence (OR = 14.87, 95% CI: [5.49; 40.32], p < 0.0001, I 2 = 9.2%) and retreatment rates (OR = 2.79, 95% CI: [1.38; 5.63], p = 0.004, I 2 = 39.2%) were significantly lower with FD. Intra and postoperative complications, total mortality, rerupture rates, and mortality from rupture did not differ significantly. Conclusion: SAC and FD demonstrate comparable short-term occlusion rates at 6 and 12 months; however, FD provides superior eventual complete occlusion, lower recurrence, and reduced retreatment rates with no significant increase in complications. FD may be favored for large or complex aneurysms, while SAC remains an effective alternative, particularly for