Introduction: The fate of aneurysms that are not completely occluded after flow diversion is controversial. Rates of progression to complete occlusion are poorly understood. Some neuro-interventionists are aggressive about early re-treatment to expedite aneurysm obliteration.
Methods: Patients treated with PED from 2011-2017 at one institution were identified. DSA follow-up was performed at 6, 12, and 24 months post-embolization. Occlusion was graded according to the Raymond-Roy scale as (1)complete, (2)neck filling, and (3)dome filling. Clopidogrel was discontinued 6 months post-embolization and Aspirin was reduced to 81mg daily 12 months post-embolization.
Results: 435 aneurysms had DSA at 6 and 12-month post-embolization, among which 69% were grade 1 at 6 months, 15% grade 2, and 15% grade 3. For grade 2/3 aneurysms, 26% progressed to grade 1 at 12 months (39% of grade 2, 12% of grade 3). 186 aneurysms had DSA at 12 and 24 months post-embolization, among which 71% were grade 1 at 12 months, 16% grade 2, and 13% grade 3. For grade 2/3 aneurysms, 44% progressed to grade 1 at 24 months (53% of grade 2, 33% of grade 3). 181 aneurysms had DSA at 6 and 24 months post-embolization, among which 62% were completely occluded at 6 months, 19% grade 2, and 18% grade 3. For grade 2/3 aneurysms, 57% progressed to grade 1 at 24 months, (71% of grade 2, 42% of grade 3).
Conclusions: Aneurysms with dome filling at 6-month DSA following PED are less likely than those with neck filling to progress to complete occlusion. A majority of those with neck filling will progress to complete occlusion by 24-month DSA. This has implications for counseling patients whose aneurysms are not occluded at the initial follow-up DSA after PED and argues for a conservative strategy regarding re-treatment.
Patient Care: These are simple data that are particularly useful in communicating with patients about what they should expect regarding occlusion of their aneurysm in the event that it is still filling at the first follow-up angiogram after flow diversion. By showing that delayed occlusion is more common than not, it will hopefully also temper a trend toward early re-treatment of aneurysms that do not occlude by the first follow-up angiogram.
Learning Objectives: To better understand the efficacy of flow diversion, the timeline of aneurysm occlusion, and the inter-relationship with tapering of antiplatelet medications.