No Delayed Ruptures on Long-Term Follow-Up of a Case Series of Persistently Filling Saccular Internal Carotid Artery Aneurysms After Flow Diversion With the Pipeline Embolization Device

BACKGROUND AND OBJECTIVES: Flow diversion of intracranial aneurysms results in high occlusion rates. However, 10% to 20% remain persistently filling at 1 year. Often, these are retreated, but benefits of retreatment are not well established. A better understanding of the long-term rupture risk of persistently filling aneurysms after flow diversion is needed. METHODS: Our institutional database of 974 flow diversion cases was queried for persistently filling saccular aneurysms of the clinoidal, ophthalmic, and communicating segments of the internal carotid artery treated with the pipeline embolization device (PED, Medtronic). Persistent filling was defined as continued flow into the aneurysm on 1 year catheter angiogram. The clinical record was queried for retreatments and delayed ruptures. Clinical follow-up was required for at least 2 years. RESULTS: Ninety-four persistent aneurysms were identified. The average untreated aneurysm size was 5.6 mm. A branch vessel originated separately in 55% of cases from the body of the aneurysm in 10.6% of cases and from the neck in 34% of cases. Eighteen percent of aneurysms demonstrated >95% filling at 1 year, and 61% were filling 5% to 95% of their original size. The mean follow-up time was 4.9 years, including 41 cases with >5 years. No retreatment was undertaken in 91.5% of aneurysms. There were no cases of delayed subarachnoid hemorrhage. CONCLUSION: Among saccular internal carotid artery aneurysms treated with PED that demonstrated persistent aneurysm filling at 1 year, there were no instances of delayed rupture on long-term follow-up. These data suggest that observation may be appropriate for continued aneurysm filling at least in the first several years after PED placement.