Angiographic Characteristics and Progression in A Comprehensive Nationwide European MOYAMOYA Cohort.

BACKGROUND: Distinct angiographic characteristics may explain clinical differences between European and East Asian MMD cohorts. This study aimed to investigate this hypothesis and explore angiographic risk factors for stroke within a Danish nationwide cohort. METHODS: We reviewed radiologic studies within a nationwide cohort of patients diagnosed with MMD from 13 clinical departments across six hospitals in Denmark between 1994 and 2017. We followed these patients until 2023, investigating angiographic progression and risk factors for stroke. RESULTS: The cohort comprised 50 patients (33 females and 17 males). Radiographic films were retrieved from 43 patients. Twenty patients were followed with DSA and 35 patients with MRA; the latter with a median interval of 4 years between the first and most recent investigations. Twelve (24%) and 38 (76%) patients had unilateral and bilateral MMD. In 90% of cases, the ICA was involved in the stenotic changes. 34% of cases showed angiographic progression, and one case progressed from unilateral to bilateral MMD (8%). Chronic ischaemic lesions were seen in 93% of patients. There was a trend towards a higher stroke risk in patients with angiographic progression (25% vs. 13%, p = 0.66), and no statistical difference in stroke risk between patients with uni- and bilateral MMD (HR 0.98, 95% CI 0.20-4.78). CONCLUSIONS: Our findings do not support the assertion of a distinct European MMD variety. Among the risk factors explored, there was a trend towards a higher stroke risk in patients with angiographic progression.