Introduction | Purpose Flow diversion (FD) has changed the landscape for minimally invasive treatment of intracranial aneurysms. The technology is supported by several clinical studies demonstrating high rates of occlusion and low rates of complications. However, safety and efficacy of these devices with extensive follow-up and in a ‘real-world’ setting is sparse. Intracranial hemorrhage (ICH) and thromboembolic events (TE) are among the most feared complications of flow diversion. The purpose of this study is to determine the incidence of these complications and to identify modifiable factors that may contribute to that risk.

Methods This retrospective review of 200 individuals across 7 institutions who received flow diverting stents between January 2015-January 2020 was conducted to perform descriptive analyses and statistical comparison (α= 0.05) of demographics, aneurysms, procedures, and complications. Data from follow-up appointments that occurred through January 2023 were included. Clinical endpoints were measured by incidence of ICH or TE, modified Rankin Scale (mRS), the National Institutes of Health Stroke Scale score (NIHSS), and World Federation of Neurosurgical Societies (WFNS) score.

Results 200 individuals underwent 210 stent placements for treatment of 234 aneurysms. Of these, 7 (3.5%) had ICH and 12 (6.0%) had TE. Within the ICH group, 3 required surgical evacuation, 4 had midline shift, 6 were subarachnoid, 1 was intraparenchymal, 5 occurred within 30 days of stent placement and none occurred in patients with a documented family history of SAH. Among patients with ICH only 1 death was associated with the procedure. Among patients with TE, 10 occurred within 30 days of procedure and none died. Table 1 shows factors we consider significant to understanding this population and their complications including: device diameter, hypertension, and need for retreatment among ICH patients as well as, pre-treatment NIHSS scores ≥ 1, and the use of aspirin with ticagrelor before or after device placement for TE patients. Complete occlusion rates were similar across all groups with a 83.9% at last follow-up (median 27.7 months).

Conclusion Complication rates in our study are comparable to previous reports, and our findings further support the general safety and efficacy of flow diversion. Despite a relatively large population, the low number of ICH and TE complications limit statistical significance. Further study of complications in more robust samples are needed. However, the descriptive understanding of these complications can help direction future investigations.

Disclosures R. Meister: None. A. Lesko: None. H. Marginean: None. V. Deshmukh: None.