1156. Natural history of asymptomatic moyamoya in a North American adult cohort

Authors: Pui Man Rosalind Lai, MD; Rose Du, MD, PhD (Boston, MA)

Introduction: The natural progression of asymptomatic moyamoya disease (MMD) remains unclear and there is no clear guideline for treatment. The goal of this study is to characterize the natural history of asymptomatic MMD patients from North America and investigate risk factors associated with radiographic progression. Methods: We retrospectively reviewed medical records of consecutive adult asymptomatic MMD patients between 1984-2018 at two tertiary teaching hospitals in Boston, Massachusetts. Cox proportional hazards regression model was used to assess risk factors associated with development of radiographic events, with surgical treatment as a time-dependent covariate to adjust for treatment effects. Outcome was defined as hemorrhage or infarction . Variables analyzed included age at presentation, age at time of diagnosis, sex, radiographic Suzuki score at diagnosis, hypertension, hyperlipidemia, the presence of an intracranial aneurysm, family history, and baseline statin, anti-hypertensive medication and aspirin use. Results: A total of 62 patients and 73 hemispheres with incidental asymptomatic MMD was included, with an average6.7±6 years follow up. 21 hemispheres underwent surgery.Cox proportional hazards regression model showed increased age (HR1.1 95%CI 1.0-1.1, p=0.034) and baseline statin use (HR16 95%CI 1.8-136, p=0.012) to be associated with hemorrhage and infarction, but no other risk factors were significant. The annual risk for stroke in the overall cohort was 1.5%/person-year, with 2.7% and 1.2%/person-year in the surgical and medical cohorts, respectively. All events in the surgical cohort occurred within 1 year, while events in the medical cohort persisted until last follow up at 24 years. Conclusion: We present the largest North American cohort of asymptomatic MMD patients and found baseline use of statin to be associated with subsequent development of infarction and hemorrhage. Surgical treatment appears to pose an initial risk but with delayed long-term benefits, while non-surgical patients had long-term progression of disease.