Association of monotherapy intervention with long-term outcomes in Spetzler-Martin grade I and II arteriovenous malformations: a nationwide multicenter observational prospective cohort study

OBJECTIVE: The aim of this study was to compare the long-term risk of hemorrhagic stroke and death between conservative management and monotherapy intervention in patients with Spetzler-Martin (SM) grade I and II brain arteriovenous malformations (AVMs). METHODS: The authors included AVMs that underwent conservative management and monotherapy intervention between August 2011 and December 2021 from a nationwide multicenter prospective collaboration registry. Patients were categorized into unruptured and ruptured cohorts for comparison of long-term outcomes, with hemorrhagic stroke and death defined as primary outcomes and neurological status as a secondary outcome. The efficacy of various intervention strategies, including resection, embolization, and stereotactic radiosurgery (SRS), was also evaluated. Stratified analyses based on intervention strategies and different SM grade subtypes were conducted. RESULTS: Of 4286 AVMs in the registry, 1013 patients were eligible for inclusion (387 with unruptured AVMs and 626 with ruptured AVMs). Overall, the intervention group showed a lower incidence of long-term hemorrhagic stroke and death compared with the conservative management group (0.43 vs 0.88 per 100 patient-years; adjusted HR [aHR] 0.61 [95% CI 0.24-1.52]), although this difference did not reach statistical significance. The results were similar in the two subgroups: aHR 0.95 (95% CI 0.28-3.18) for unruptured AVMs and aHR 0.29 (95% CI 0.06-1.32) for ruptured AVMs. Stratified analyses based on different intervention strategies and different SM grade subtypes showed that resection might benefit both unruptured (0.00 vs 0.79 per 100 patient-years, p = 0.006) and ruptured (aHR 0.12 [95% CI 0.03-0.53], p = 0.033) AVMs, while SRS might only benefit ruptured AVMs (aHR 0.04 [95% CI 0.01-0.34], p = 0.163). Embolization and SRS might not be beneficial for unruptured low-grade AVMs. CONCLUSIONS: In this observational prospective cohort study, intervention demonstrated benefit over conservative management in preventing long-term hemorrhagic stroke or death in patients with SM grade I or II AVMs. Among specific monotherapy interventions, resection proved favorable for both unruptured and ruptured SM grade I and II AVMs, while SRS might serve as a reasonable alternative in ruptured cases.