Cortical superficial siderosis and bleeding risk in cerebral amyloid angiopathy

Abstract

ObjectiveTo assess the association of cortical superficial siderosis (cSS) presence and extent with future bleeding risk in cerebral amyloid angiopathy (CAA).MethodsThis was a meta-analysis of clinical cohorts of symptomatic patients with CAA who had T2*-MRI at baseline and clinical follow-up for future intracerebral hemorrhage (ICH). We pooled data in a 2-stage meta-analysis using random effects models. Covariate-adjusted hazard ratios (adjHR) from multivariable Cox proportional hazard models were used.ResultsWe included data from 6 eligible studies (n = 1,239). cSS pooled prevalence was 34% (95% confidence interval [CI] 26%–41%; I2 87.94%; p < 0.001): focal cSS prevalence was 14% (95% CI 12%–16%; I2 6.75%; p = 0.37), and disseminated cSS prevalence was 20% (95% CI 13%–26%; I2 90.39%; p < 0.001). During a mean follow-up of 3.1 years (range 1–4 years), 162/1,239 patients experienced a symptomatic ICH-pooled incidence rate 6.9% per year (95% CI 3.9%–9.8% per year; I2 83%; p < 0.001). ICH incidence rates per year according to cSS status were 3.9% (95% CI 1.7%–6.1%; I2 70%; p = 0.018) for patients without cSS, 11.1% (95% CI 7%–15.2%; I2 56.8%; p = 0.074) for cSS presence, 9.1% (95% CI 5.5%–12.8%; I2 0%; p = 0.994) for focal cSS, and 12.5% (95% CI 5.3%–19.7%; I2 73.2%; p = 0.011) for disseminated cSS. In adjusted pooled analysis, any cSS presence was independently associated with increased future ICH risk (adjHR 2.14; 95% CI 1.19–3.85; p < 0.0001). Focal cSS was linked with ICH risk (adjHR 2.11; 95% CI 1.31–2.41; p = 0.002), while disseminated cSS conferred the strongest bleeding risk (adjHR 4.28; 95% CI 2.91–6.30; p < 0.0001).ConclusionIn patients with CAA, cSS presence and extent are the most important MRI prognostic risk factors for future ICH, likely useful in treatment planning.Classification of evidenceThis study provides Class III evidence that in symptomatic CAA survivors with baseline T2*-MRI, cSS (particularly if disseminated, i.e., affecting >3 sulci) increases the risk of future ICH.