Early EEG and serum biomarkers for prognostication after cardiac arrest.

Rationale: Early electroencephalography (EEG), initiated within 12 h after cardiac arrest, allows reliable prognostication in approximately 50 % of comatose patients. Serum biomarkers may complement early EEG-based outcome prediction, particularly in indeterminate cases. We evaluated the potential additive prognostic value of the serum biomarkers neuron-specific enolase (NSE), neurofilament light chain (NfL), S100 calcium binding protein Methods: In this pilot study, we analysed serum biomarker concentrations at multiple time points (<12 h, 24 h, 72 h, 7 days) post-CA in comatose out-of-hospital CA patients included in the ghrelin in coma (GRECO) trial. EEG recordings were visually evaluated at 12 and 24 h post-arrest. Neurological outcomes were assessed using the Cerebral Performance Category (CPC) score at 6 months, dichotomised into good (CPC 1-2) or poor (CPC 3-5). Results: A total of 49 patients were included; 24 (49 %) had a poor neurological outcome at 6 months. Serum biomarker concentrations were significantly higher in poor-outcome patients within 24 h post-CA. NfL achieved an AUC of 0.90, followed by p-Tau181 (AUC 0.81), S100B (AUC 0.80) and NSE (AUC 0.76) for poor neurological outcome at 24 h post-CA. In 40 patients with EEG, NfL > 100 pg/mL reclassified indeterminate cases as likely poor outcome, with >128 pg/mL at any time achieving 100 % specificity, unlike other biomarkers. Significance: NfL demonstrated superior prognostic performance compared to other serum biomarkers. Our preliminary findings suggest added prognostic value of NfL when combined with early EEG (12-24 h), particularly in patients with indeterminate EEG findings.