Early Prediction of Space-Occupying Hemispheric Infarction: Development and Validation of the Malignant Edema Risk Assessment Score: Results From the PREDICT-MMI Study.

BACKGROUND: Space-occupying hemispheric infarction is a severe complication after acute ischemic stroke due to large-vessel occlusion (LVO). Early identification of patients at risk is clinically crucial. In the PREDICT-MMI (Prospective Evaluation of Clinical Parameters and Initial Cerebral CT for the Prediction of Malignant Media Infarction) study, we developed and validated the Malignant Edema Risk Assessment score to predict the individual risk of space-occupying infarction after LVO. METHODS: Four predefined logistic models were assessed in a retrospective derivation cohort of patients with anterior-circulation LVO. Models sequentially included net water uptake (estimated from the first non-contrast-enhanced computed tomography; model 0) plus intracranial cerebrospinal fluid volume (model 1) plus clinical data (age, LVO localization, National Institutes of Health Stroke Scale score at admission, recanalization success; model 2) plus laboratory parameters reflecting fluid status (model 3). The best-performing model was prospectively validated in patients enrolled between September 2023 and February 2025. RESULTS: The derivation cohort included 155 patients, of whom 84 (54.2%) developed a space-occupying hemispheric infarction. Model 2 performed best (Malignant Edema Risk Assessment score ≥66.6%: sensitivity, 75.0%; specificity, 86.3%; area under the curve, 0.853 [95% CI, 0.801-0.918]). The validation cohort included 156 patients, of whom 28 (17.9%) developed a space-occupying hemispheric infarction. Applying the predefined Malignant Edema Risk Assessment cutoff yielded a sensitivity of 85.7%, specificity of 85.9%, positive predictive value of 57.1%, negative predictive value of 96.5%, and area under the curve of 0.942 (95% CI, 0.909-0.980). CONCLUSIONS: The Malignant Edema Risk Assessment score allows an early and accurate identification of patients at high risk of developing a space-occupying hemispheric infarction after acute ischemic stroke due to LVO. REGISTRATION: URL: https://drks.de/; Unique identifier: DRKS00033266.