Multicenter Arteriovenous Malformation Research Study (MARS)

Brain arteriovenous malformations (bAVMs) are a leading cause of hemorrhagic stroke in younger people. Surgery and other invasive treatments pose risks that may outweigh its benefits, especially for patients who are diagnosed with an unruptured bAVM, which has not yet caused bleeding in the brain. Doctors still find it challenging as to whether or not they should treat an unruptured bAVM, carefully monitor their patients, or only treat those at higher risk of hemorrhage. The goal of this project was to conduct a large, multi-center study to estimate the long-term risk of hemorrhage in untreated and treated patients diagnosed with unruptured bAVMs to better inform clinical care and treatment decisions. 

For this project, we collected data from unruptured bAVM patients seen at 5 sites in the U.S. and 5 sites outside the U.S. (U.K., Finland, Australia, China, and Brazil). We collected clinical, imaging, treatment, and outcome data from medical records or surveys at diagnosis and during follow-up. Individual-level data were pooled together for analysis from 3,262 unruptured bAVM patients, with 12,044 person-years of follow-up time while untreated and 20,035 person-years of follow-up time after treatment.