Long-Term Outcomes and Natural Course of Giant Cerebral Arteriovenous Malformations (> 6 cm): Insights From a National Multicenter Propensity Score-Matched Cohort.

[OBJECTIVES] This study evaluated the natural history of giant cerebral arteriovenous malformations (AVMs) over 6 cm and compared long-term outcomes of interventional treatment versus conservative management.

[MATERIALS AND METHODS] Patients with AVMs > 6 cm were identified from a national multicenter prospective registry (MATCH). Rupture risk factors were analyzed with uni- and multivariate models. Propensity score matching balanced intervention and conservative groups. The primary outcome was long-term hemorrhagic stroke or death; secondary outcomes included obliteration rates and neurological status. Subgroup and sensitivity analyses assessed robustness.

[RESULTS] From August 2011 to December 2021, 380 patients with giant AVMs were enrolled. Annual rupture risk was 2.4% for unruptured lesions, 9.4% for previously ruptured, and 3.6% overall. Ventricular involvement (OR = 3.61) and draining vein stenosis (OR = 2.61) were independent hemorrhage risk factors. Over a mean follow-up of 7.3 years, intervention did not significantly reduce hemorrhagic stroke or death compared to conservative management but was associated with higher hemorrhagic stroke risk (HR = 2.04) and neurological deterioration, despite higher obliteration rates (39.1%). Stratified analysis suggested microsurgery and embolization alone were less favorable, while embolization plus radiosurgery more effectively reduced hemorrhagic stroke or death. Subgroup analysis indicated conservative management was preferable for higher S-M grades, unruptured AVMs, and eloquent brain regions.

[CONCLUSION] The annual rupture rate of giant AVMs (> 6 cm) is approximately 3.6%. Interventional treatment for giant AVMs is not superior to conservative management, and the risks of hemorrhagic stroke and neurological deterioration remain substantial-particularly for unruptured, high-grade, or eloquently located AVMs.