We aimed to investigate cortical superficial siderosis as an MRI predictor of lobar intracerebral hemorrhage (ICH) recurrence risk in cerebral amyloid angiopathy (CAA), in a large prospective MRI cohort and a systematic review.

We analyzed a single-center MRI prospective cohort of consecutive CAA-related ICH survivors. Using Kaplan–Meier and Cox regression analyses, we investigated cortical superficial siderosis and ICH risk, adjusting for known confounders. We pooled data with eligible published cohorts in a two-stage meta-analysis using random effects models. Covariate-adjusted hazard rations (adj-HR) from pre-specified multivariable Cox proportional hazard models were used.

The cohort included 240 CAA-ICH survivors (cortical superficial siderosis prevalence: 36%). During a median follow-up of 2.6 years (IQR: 0.9–5.1 years) recurrent ICH occurred in 58 patients (24%). In prespecified multivariable Cox regression models, cortical superficial siderosis presence and disseminated cortical superficial siderosis were independent predictors of increased symptomatic ICH risk at follow-up (HR: 2.26; 95% CI: 1.31–3.87, p = 0.003 and HR: 3.59; 95% CI: 1.96–6.57, p < 0.0001, respectively). Three cohorts including 443 CAA-ICH patients in total were eligible for meta-analysis. During a mean follow-up of 2.5 years (range: 2–3 years) 92 patients experienced recurrent ICH (pooled risk ratio: 6.9% per year, 95% CI: 4.2%–9.7% per year). In adjusted pooled analysis, any cortical superficial siderosis and disseminated cortical superficial siderosis were the only independent predictors associated with increased lobar ICH recurrence risk (adj-HR: 2.4; 95% CI: 1.5–3.7; p < 0.0001, and adj-HR: 4.4; 95% CI: 2–9.9; p < 0.0001, respectively).

In CAA-ICH patients, cortical superficial siderosis presence and extent are the most important MRI prognostic risk factors for lobar ICH recurrence. These results can help guide clinical decision making in patients with CAA.