Objective: We evaluated recurrent intracerebral hemorrhage (ICH) risk in ICH survivors, stratified by the presence, distribution and number of cerebral microbleeds (CMBs) on MRI (i.e. the presumed causal underlying small vessel disease, and its severity).
Methods: Meta-analysis of prospective cohorts following ICH, with blood-sensitive brain MRI soon after ICH. We estimated annualized recurrent symptomatic ICH rates for each study and compared pooled odds ratios of recurrent ICH by CMB presence/absence, presumed etiology based on CMBs distribution (strictly lobart CMBs related to probable or possible cerebral amyloid angiopathy [CAA] vs. non-CAA), and burden (1, 2-4, 5-10 and >10 CMBs), using random effects models.
Results: We pooled data from ten studies including 1306 patients: 325 with CAA-related and 981 CAA-unrelated ICH. The annual recurrent ICH risk was higher in CAA-related ICH vs. CAA-unrelated ICH (7.4%, 95%CI 3.2-12.6 vs. 1.1%, 95%CI 0.5-1.7 per year, respectively; p=0.01). In CAA-related ICH, multiple baseline CMBs (versus none) were associated with ICH recurrence during follow-up (range 1-3 years): OR 3.1 (95%CI 1.4-6.8; p=0.006), 4.3 (95%CI 1.8-10.3; p=0.001) and 3.4 (95%CI 1.4-8.3; p=0.007) for 2-4, 5-10 and >10 CMBs respectively. In CAA-unrelated ICH, only >10 CMBs (versus none) were associated with recurrent ICH (OR 5.6, 95%CI 2.1-15; p=0.001). The presence of one CMB (versus none) was not associated with recurrent ICH in CAA-related or CAA-unrelated cohorts.
Conclusions: CMB burden and distribution on MRI identify sub-groups of ICH survivors with higher ICH recurrence risk, which may help to predict ICH prognosis with relevance for clinical practice and treatment trials.