Abstract 18: Diffusion Weighted Imaging Lesions in Patients With Acute Intracerebral Hemorrhage: A Pooled Analysis of Individual Patient Data From MISTIE-III, ATACH-II, I-DEF, and ERICH

Introduction: The etiology and significance of diffusion weighted imaging (DWI) lesions in patients with acute intracerebral hemorrhage (ICH) remain unclear. We evaluated which factors were associated with DWI lesions, whether associated factors differed by ICH location, and whether DWI lesions were associated with functional outcomes. Methods: We pooled individual patient data from the MISTIE III trial, the ATACH-II trial, the i-DEF trial, and the ERICH study. We included only patients who underwent protocolized magnetic resonance imaging (MRI) of the brain. A poor functional outcome was defined as a modified Rankin Scale (mRS) score of 4-6 at 3-6 months. We used mixed effects logistic regression with the study database as a random effect. Results: Among 1,775 ICH patients, there were 621 (35.6%) lobar, 978 (55.9%) deep, and 148 (8.5%) infratentorial ICHs. Median time to MRI scan was 1.5 days (IQR, 1-4). DWIHLs occurred in 559 (31.5%) patients, with 190 (34.3%) in lobar ICH and 320 (57.8%) in deep ICHs. In mixed effects regression models, factors associated with DWIHLs included younger age factors associated with DWIHLs after acute ICH included younger age (OR, 0.98; 95% CI, 0.97-0.99), black race (OR, 1.59; 95% CI, 1.18-2.16), admission systolic blood pressure (SBP per 10 mm Hg, OR, 1.13; 95% CI, 1.05-1.22), cerebral microbleeds (OR, 1.71, 95% CI, 1.24-2.35), and leukoaraiosis (OR, 1.60; 95% CI, 1.14-2.25). Patients with DWIHLs had higher odds of mRS 4-6 (OR, 1.57; 95% CI, 1.24-1.99) compared to those without, after adjustment for demographics and ICH severity. In subgroup analyses, similar factors influenced DWIHLs in deep ICH. However, in lobar ICH, younger age, admission SBP, and leukoaraiosis were associated with DWIHLs. Presence of DWIHLs was independently associated with poor mRS in deep ICH but not in lobar ICH. There was no relationship between acute BP lowering and DWIHLs, regardless of location. Conclusions: In a large, heterogeneous cohort of ICH patients, our results are consistent with the hypothesis that DWIHLs represent the effects of chronic hypertensive vasculopathy and acute blood pressure elevation. Furthermore, DWIHLs portend poor prognosis after ICH, particularly in deep hemorrhages.