Disease progression, transient ischemic attack, and de novo parenchymal lesions in asymptomatic moyamoya disease: Results of a 5-year interim analysis of the AMORE study

OBJECTIVE Recently, the authors have reported the 5-year risk of stroke in patients with asymptomatic moyamoya disease (MMD). In this report, the aim was to clarify patients' 5-year risk of disease progression, transient ischemic attack (TIA), and de novo parenchymal lesions and to identify their predictors. METHODS This multicenter, prospective cohort study (Asymptomatic Moyamoya Registry [AMORE]) in Japan is still ongoing. Participants were enrolled if they were 20-70 years of age, had bilateral or unilateral MMD, experienced no episodes suggestive of TIA and stroke, were functionally independent (modified Rankin Scale score of 0 or 1), and had been followed up for 10 years. Clinical and radiological data were obtained at enrollment and annually thereafter for 5 years. In this 5-year interim analysis, the authors defined disease progression, TIA, and de novo parenchymal lesions as the secondary endpoints. The predictors for these events were identified, using a stratification analysis method. RESULTS A total of 103 patients were enrolled and prospectively followed up for 5 years. On annual MRA examinations, disease progression occurred in 39 hemispheres in 26 patients. The incidence of disease progression was 5.9% per patient-year, and the predictors included younger age (OR 5.72, 95% CI 1.28-25.56; p = 0.0223) and hypercholesterolemia (OR 5.41, 95% CI 1.37-21.28; p = 0.0158). TIA occurred in 12 hemispheres in 10 patients, for an incidence of 2.3% per patient-year. The disease progression prior to TIA was a significant predictor for TIA (OR 5.00, 95% CI 1.31-19.0; p = 0.0184). De novo microbleeds were found in 11 hemispheres in 10 patients (2.3% per patient-year). The presence of microbleeds at enrollment was a significant predictor for de novo microbleeds (OR 5.53, 95% CI 1.17-26.13; p = 0.0309). CONCLUSIONS Patients with asymptomatic MMD may carry a significant risk of disease progression, TIA, and de novo microbleeds during the first 5 years after initial diagnosis. Practitioners should very carefully follow up with them to improve their outcome, using MRI and MRA at regular intervals.