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. Clinical trial registration no.: UMIN000006640 ( https://www.umin.ac.jp ).