Abstract Number: Esoc2026a1924 Long-Term Outcomes of Conservatively Managed Unruptured Brain Arteriovenous Malformations: A Single-Center Retrospective Cohort Study

Abstract Background and aims Unruptured brain arteriovenous malformations (bAVMs) are traditionally associated with an annual haemorrhage risk of 2–4%. ARUBA trial on the management of unruptured bAVM reported superior outcomes with conservative management. This study aimed to assess long-term clinical outcomes and risk factors for intracranial haemorrhage (ICH) in conservatively managed unruptured bAVMs. Methods In this single-centre retrospective cohort study, patients with unruptured bAVMs were initially managed conservatively. The primary outcome was de novo ICH during follow-up. Secondary outcomes included mortality, new neurological symptoms, need for intervention, and functional status. Results A total of 126 patients (mean age 44.8 years) were included, with 700 person-years of follow-up. AVM diameter was 3 cm in 77 (61%), 3–6 cm in 46 (37%), and 6 cm in 3 (2%) patients. Twelve first ICH events occurred, yielding an incidence rate of 1.71 per 100 person-years (95% confidence interval CI, 0.75–2.68). Seven patients (5.6%) died, six due to ICH. In univariable Cox analyses, flow-related aneurysms (hazard ratio HR 9.49, 95% CI 2.86–31.44) and AVM diameter ≥6 cm (HR 10.42, 95% CI 1.18–91.82) were associated with increased ICH risk. Most patients remained clinically and functionally stable; eight patients (6.3%) required intervention during follow-up, including four after ICH. Conclusions In this real-world cohort of conservatively managed unruptured bAVMs, long-term ICH risk was low. Large AVM diameter and flow-related aneurysms were potential risk factors, supporting conservative management in line with the ARUBA trail, while highlighting the need for individualized risk stratification. Conflict of interest Danae Kingma: nothing to disclose