Early consciousness recovery after cardiac arrest (CA) is one of the most explicit and self-evident prognostic factors for clinical outcomes. We aimed to evaluate the prognostic value of electroencephalography (EEG) phenotypes according to the American Clinical Neurophysiology Society’s Critical Care EEG classification for predicting early recovery after CA.

Consecutive patients admitted to the ICU after CA were enrolled. We analyzed Glasgow Coma Scale (GCS) score within 10 days after CA and evaluated mortality within 28 days according to EEG pattern subtype.

Among the total of 71 patients, 9 had periodic discharges (PDs) EEG pattern, 4 had rhythmic delta activity (RDA), 8 had spike-and-wave (SW), 22 had low voltage, 5 had burst suppression, and 23 had other EEG patterns. Initial GCS scores, GCS scores 3 days after CA (or 3 days after targeted temperature management [TTM]), and 10 days after CA (or 10 days after TTM) were significantly different among EEG subtypes (p < 0.001, respectively) (Table 2). GCS scores were significantly higher in RDA and the other EEG group compared to the PDs, SW, low voltage, and burst suppression groups (p < 0.001). Significant group × time interactions were observed for the follow-up period between EEG phenotypes (p < 0.001) demonstrating the most increase in the other EEG pattern group.

Consciousness states were significantly worse in the PDs, SW, burst suppression, and low-voltage groups compared to the RDA and the other EEG pattern within 10 days after CA. The degree of consciousness recovery differed significantly by EEG pattern subtype within 10 days.