Abstract 287: Does Surface Modification Improve Outcomes? Predictors of Complete Aneurysm Occlusion at First Angiographic Follow‐Up After Flow Diversion: A Cox Regression Analysis

Introduction The true risk of aneurysm hemorrhage or rehemorrhage following flow diversion stems from the duration an aneurysm remains unoccluded after treatment. Most existing literature emphasize final occlusion as the primary efficacy metric, overlooking early angiographic outcomes at first follow‐up. Predictors of complete occlusion include neck width, absence of hypertension, adjunctive coiling, and immediate post‐deployment occlusion and longer follow‐up. However, the temporal dynamics of occlusion remain underexplored. Materials/Methods To identify antithrombotic, procedural, aneurysmal, and device‐related predictors of complete aneurysm occlusion—defined as Raymond‐Roy Occlusion Classification I or O’Kelly‐Marotta Grade D—at the first digital subtraction angiography (DSA) follow‐up after: (1) All Flow diversion, and (2) Surface modified flow diversion (PED Shield, PED Vantage, FRED X or Surpass Evolve). Cox regression analysis using a backward likelihood‐ratio method was performed on a prospectively maintained institutional database of 765 intracranial aneurysms treated with flow diversion from 2013 to 2024. Results All flow diversion Significant negative predictors of complete aneurysm occlusion included: older age (HR=0.989/year, p=0.005), long‐term ongoing single (HR=0.639, p=0.004) or dual (HR=0.393, p<0.001) antiplatelet therapy versus none, use of surface‐modified flow diverters (HR=0.491, p<0.001; Figure‐1), larger proximal arterial diameter (HR=0.775 per mm, p=0.006), and longer discharge antiplatelet duration (HR=0.999/day, p<0.001). Cox regression analysis specific to Pipeline Embolization Devices (PED) revealed similar patterns, with lower rates of complete aneurysm occlusion associated with the use of PED Shield (HR=0.51, p<0.001) or PED Vantage (HR=0.574, p=0.08) compared to PED Classic/PED Flex (Figure‐2). Surface modified flow diversion Significant predictors of complete aneurysm occlusion at first DSA follow‐up after SMFD included (Figure‐3): younger age (HR=0.97 per year, p=0.038), male sex (HR=0.31, p=0.042), Asian race (HR=0.05, p=0.001) or Hispanic/Native‐American race (HR=10.06, p=0.015) compared to White/Caucasian cohorts, former smoking status compared to current smoking (HR=3.00, p=0.008), family history of stroke (HR=0.35, p=0.029), recurrent aneurysms (HR=7.27, p=0.003), platelet reactivity unit <180 (HR=0.14, p=0.003), neck width (HR=0.69/mm, p=0.032), discharge on ticagrelor compared to clopidogrel (HR=0.30, p=0.002), and shorter duration of discharge antiplatelet medication (HR=0.996/day, p=0.035). Conclusion The study highlights the importance of optimizing discharge antiplatelet management to improve early aneurysm occlusion, especially in patients on chronic therapy for CAD, prior strokes, or PVD. Surface‐modified flow diverters, despite reducing intimal hyperplasia by mimicking endothelial components, were associated with delayed occlusion and incomplete neck coverage. Baseline coagulation status and discharge antithrombotic regimens also significantly influenced outcomes, underscoring opportunities to tailor therapy across diverse patient populations. image