Evaluate the Full Outline of Unresponsiveness (FOUR) and revised post-Cardiac Arrest Syndrome for Therapeutic hypothermia (rCAST) scores for predicting hypoxic ischemic brain injury (HIBI) on early head computed tomography (CT) following cardiac arrest (CA).

HIBI on early head CT is associated with poor neurologic outcome and brain death.

In this single-center, retrospective study of CA patients admitted between 2014-2022, early head CT was defined as within 6 hours of CA and HIBI was scored if early head CT radiology report documented 1) loss of gray-white matter differentiation, 2) sulcal effacement, 3) cerebral edema. Area under the receiver operating curve (AUC) was computed to assess rCAST and FOUR scores’ accuracy for predicting HIBI on early head CT.

Early head CT was performed in 55.5% (420/757) of patients; 108 (25.7%) had HIBI. Patients with HIBI were younger (mean (standard deviation) 50.7 (15.8) vs. 62.0 (16.7) years, p<0.001), healthier (median [interquartile range] Charlson Comorbidity Index 2 [0;4] vs. 4 [1;6], p <0.001), and presented with more severe post-CA syndrome (initial lactate 12.2 (4.6) vs. 8.5 (4.2), p<0.001; initial pH 7.23 (0.2) vs. 7.28 (0.2), p=0.011; rCAST 11.5 (3.7) vs. 8.3 (3.9), p<0.001; FOUR score 0.9 (1.5) vs. 3.6 (3.4), p <0.001). HIBI was associated with lower hospital survival (1.9% vs. 29.5%, p <0.001). The AUC of the rCAST and FOUR score for predicting HIBI were 0.735 [0.659; 0.811] and 0.762 [0.702; 0.826], respectively.

Just over half of our CA cohort underwent early head CT and one in four had HIBI, which was associated with high mortality. Available, valid scores (FOUR and rCAST) associated with CA outcome may be helpful in early head CT patient selection. These findings warrant validation in a larger prospective cohort not limited by early withdrawal of life-sustaining therapy.