Introduction and Objective: Lobar cerebral microbleed (CMB) is frequently found in patients with spontaneous intracerebral hemorrhage (ICH) and is closely linked to cerebral amyloid angiopathy (CAA) and risk of recurrent ICH. Lobar CMB could be further topographically categorized into intracortical type or subcortical white matter (WM) type, and our previous study showed that CAA is more related to the intracortical lobar CMB. The current study aimed to determine if the types of lobar CMB can predict risks ofrecurrent ICH and long-term vascular outcomes in patients with spontaneous ICH. Methods: A total of 587 patients with spontaneous ICH were included. Clinical data, neuroimaging markers, and 2-year follow-up outcomes (recurrent ICH, incident ischemic stroke, vascular mortality and composite outcome) were collected. We categorized patients into 4 different groups based on their lobar CMB types: Type 1 (strictly intracortical type, n=52), Type 2 (strictly subcortical WM type, n=127), Type 3 (mixed intracortical and subcortical WM type, n=86), and Type 4 (no lobar CMB, n=277). The associations between lobar CMB type and follow-up outcomes were assessed using multivariable Cox regression models with adjustment of age, sex, hypertension, diabetes mellitus and hyperlipidemia. We also examined the dose-relationship between intracortical lobar CMB number and ICH recurrence risk. Results: Compared to patients without lobar CMB (Type 4), patients with strictly intracortical lobar CMB type (Type 1) had higher ICH recurrence rate (HR 3.90[1.30-11.75], p=0.015) and composite outcomes (HR 2.55[1.26-5.17], p=0.009], p<0.001), while patients with strictly subcortical WM lobar CMB type (Type 2) was associated with high risk of composite outcomes (HR 2.22[1.31-3.79], p=0.003) and a trend toward risk of incident ischemic stroke (HR 2.12 (0.89-5.05), p=0.091) but not ICH (HR 1.66 [0.66-4.19], p=0.282). Mixed type (Type 3) was not associated with follow-up vascular events. For patients with at least one lobar CMB, three or more intracortical CMBs significantly elevated ICH recurrence risk (HR 2.85 [1.18-6.88], p=0.020). Conclusions: Topographical type of lobar CMB may have clinical significance in predicting ICH recurrence risks and vascular outcomes in ICH survivors. Patients with lobar CMBs restricted in the intracortical region, or with multiple number of intracortical lobar CMBs, are predisposed to higher ICH recurrence rate.
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