Association of the combined stereotactic radiosurgery and embolization strategy and long-term outcomes in brain arteriovenous malformations with a volume > 10 ml: A nationwide multicenter observational prospective cohort study

Background: To assess the long-term outcome of large brain arteriovenous malformations (AVMs) (volume > 10 ml) underwent combined embolization and stereotactic radiosurgery (E+SRS) versus SRS alone. Methods: Patients were recruited from a nationwide multicenter prospective collaboration registry (MATCH study, August 2011-August 2021) and categorized into E+SRS and SRS alone cohorts. Propensity score-matched survival analysis was employed to control for potential confounding variables. The primary outcome was a composite event of non-fatal hemorrhagic stroke or death. Secondary outcomes were favorable patient outcomes, AVM obliteration, favorable neurological outcomes, seizure, worsened mRS score, radiation-induced changes (RIC), and embolization complications. Furthermore, the efficacy of distinct embolization strategies was evaluated. Hazard ratios (HRs) were computed utilizing Cox proportional hazard models. Results: Among 1063 AVMs who underwent SRS with or without prior embolization, 176 patients met the enrollment criteria. Following propensity score matching, the final analysis encompassed 98 patients (49 pairs). Median (interquartile range) follow-up duration for primary outcomes spanned 5.4 (2.7-8.4) years. Overall, the E+SRS strategy demonstrated a trend toward reduced incidence of primary outcomes compared to the SRS alone strategy (1.44 vs 2.37 per 100 patient-years; HR, 0.58 [95 % CI, 0.17-1.93]). Regardless of embolization degree or strategy, stratified analyses further consistently revealed a similar trend, albeit without achieving statistical significance. Secondary outcomes generally exhibited equivalence, but the combined approach showed potential superiority in most measures. Conclusions: This study suggests a trend toward lower long-term non-fatal hemorrhagic stroke or death risks with the E+SRS +SRS strategy when compared to SRS alone in large AVMs (volume > 10 ml).