Long-term stroke risk in Moyamoya disease

Background: Moyamoya disease (MMD) is considered a progressive disease with an ongoing risk of recurrent stroke. However, there is a lack of long-term observational data to quantify the extent of the stroke risk. Methods: This study aimed to provide insight into the long-term stroke risk in MMD and explore possible risk factors for stroke. Records from all patients diagnosed with MMD in 13 clinical departments from 6 different Danish hospitals between 1994 and 2017 were retrospectively reviewed until 2021. Results: The cohort comprised 50 patients (33 females and 17 males). Patients were followed up for a median of 9.4 years, with more than 10 years of follow-up for 24 patients. Ten patients had 11 new stroke events—6 ischemic strokes and 5 brain hemorrhages. Events occurred at a median of 7 years and up to 25 years after diagnosis. The overall Kaplan-Meier 5-year stroke risk was 10%. Patients with bypass performed had significantly fewer events than conservatively treated patients (HR 0.25, 95% confidence interval (CI) 0.07–0.91, p < 0.05). All but one event occurred in females, a difference that reached statistical significance. Conclusions: The study provides data on the extent of the risk of recurrent stroke in MMD. Bypass surgery patients had fewer stroke events than those treated conservatively. There was a trend toward a higher stroke risk in females. Data access statement: The data supporting this study’s findings are available from the corresponding author upon reasonable request.