Intracranial Aneurysms Treated with Pipeline Embolization Device with Incomplete Occlusion at One Year: Strategies to Enhance Delayed Occlusion?

Introduction: The Pipeline embolization device (PED) has become widely accepted as a safe and efficacious treatment of intracranial aneurysms with high rates of complete occlusion at one year follow up. For aneurysms that are not completely occluded at one-year, further treatment decision making is varied. The aim of this study was to analyze aneurysms treated with PED with incomplete occlusion at one year and determine treatment paradigms that lead to complete occlusion beyond one year.

Methods: This study is a retrospective review of prospective data for intracranial aneurysms treated with PED at a single institution from 2013-2022. Aneurysms with near-complete or incomplete occlusion at one year follow up were included in the statistical analysis.

Results: There were 457 total aneurysms treated with PED with incomplete occlusion at one year follow up in 59 aneurysms (12.9%). Of the 59 aneurysms that were non occluded at one year, 23 aneurysms (39.0%) went on to occlude at final follow up for final complete occlusion of 94.96%. Time to final imaging follow up was 35.7 months (IQR 26.6 – 48.5) Antiplatelet change to Aspirin 81mg was the most commonly used antiplatelet regimen in 24 patients, (40.7%). Retreatment with a second flow diverter was used in 16 aneurysms (27.1%). No aneurysms that were incompletely occluded at one year had delayed rupture. Older patient age was statistically significant for incomplete occlusion at one year follow up (p=0.04).

Conclusion : Intracranial aneurysms treated with the Pipeline embolization device that do not occlude at one year may go on to complete occlusion over subsequent follow up. Delayed aneurysmal rupture was not seen in patients with incomplete occlusion.