Abstract DP035: White Matter Hyperintensities Are Associated with Worse Outcomes but Not Greater Cerebral Edema or Hemorrhagic Transformation After Large Vessel Occlusion Stroke

Introduction: White Mattery Hyperintensities (WMH) are key radiographic biomarkers of cerebral small vessel disease (CSVD). WMH has been associated with worse outcomes after stroke but factors mediating this association are not fully known. Since CSVD may be associated with blood-brain barrier disruption, we hypothesized that WMH would be associated with more severe cerebral edema and hemorrhagic transformation. Methods: We included patients from four international stroke cohorts if they presented within 24 hours of anterior circulation large vessel occlusion (LVO) stroke and received at least one follow-up CT scan between 12-48 hours after stroke onset. WMH presence was rated on baseline CTs using the previously adapted Fazekas-derived grading system. We applied automated image analysis to measure CSF displacement (ΔCSF) and ratio of lesional versus contralateral hemispheric CSF volumes (CSF-ratio) as quantitative measures of edema severity. Good recovery was defined as an mRS of 0-2. Univariate and multivariable linear regressions were used to evaluate associations between WMH and edema severity along with logistic regressions of HT and mRS, adjusting for key clinical and imaging covariates, with subgroup analyses in patients undergoing thrombectomy and in those with successful reperfusion. Results: Of the 1,290 patients in the four cohorts, 782 underwent successful imaging analysis. Of these, 18% had WMH on CT. Patients with WMH were older, more likely female, and had higher presenting systolic blood pressure and serum glucose. WMH was significantly associated with worse functional outcome, adjusting for age, NIHSS, glucose, and other covariates OR 1.84 (1.06, 3.22), p = 0.04 but with lower risk of any HT OR 0.48 (0.25-0.88), p=0.03. However, WMH presence was not associated with greater edema (whether ΔCSF, CSF-ratio, midline shift, or net water uptake), in the whole population or any subgroups. Reperfusion after thrombectomy was associated with both lower edema severity and improved recovery. Conclusions: We demonstrated that the presence of WMH, assessed on admission CT, is associated with lower odds of good outcome after LVO stroke, independent of age and other factors. However, this risk does not appear to be mediated through increased risk of HT or greater cerebral edema formation.