Apolipoprotein E Genotype Predicts Hematoma Expansion in Lobar Intracerebral Hemorrhage

Background and Purpose-Hematoma volume is the most potent predictor of outcome in spontaneous intracerebral hemorrhage (ICH), and hematoma expansion after hospital presentation occurs in up to 40% of individuals. Among patients with lobar ICH, the apolipoprotein E (APOE) epsilon 2 allele predicts larger hematoma volumes at presentation. We investigated whether the epsilon 2 allele also identifies individuals at increased risk of hematoma expansion. Methods-We analyzed 510 patients with primary ICH and genetic data available from an ongoing prospective cohort study. Baseline and follow-up CT scans were assessed for ICH location and volume using computer-assisted volumetric methods. Results-Individuals with lobar ICH who possessed APOE epsilon 2 were at increased risk for hematoma expansion (OR, 2.72; 95% CI, 1.19-6.23; P = 0.009). The highest odds of expansion were in patients who qualified for the diagnosis of cerebral amyloid angiopathy-related ICH and carried the APOE epsilon 2 allele (OR, 6.02; 95% CI, 1.60 -22.58; P = 0.008). There was no effect of epsilon 2 on hematoma expansion in deep ICH and APOE epsilon 4 had no effect on hematoma expansion in lobar or deep ICH. Conclusions-Possession of APOE epsilon 2 predisposes individuals with lobar ICH to hematoma expansion. This effect is even more pronounced in patients with amyloid angiopathy-related ICH, consistent with the epsilon 2 allele's role in vascular amyloid deposition and vessel fragility. (Stroke. 2012; 43: 1490-1495.)