Intra-burst Theta During Burst-suppression Pattern in Comatose Postcardiac Arrest Patients Correlates with Outcome; a Prospective Study

Objective: To examine the association of intra-burst frequency during electroencephalographic burst-suppression pattern (BSP) with clinical outcomes in comatose post-cardiac arrest (CA) patients. Background: Mechanisms of neuronal recovery are not well characterized after CA. Recent studies proposed BSP as a general mechanism when low levels of adenosine triphosphate (ATP) are present leading to protection of membrane integrity in the setting of low metabolic substrate availability. In previous case series and a retrospective cohort analysis we found that theta-bursting (~4–7Hz) during BSP correlates with favorable outcomes after CA, indicating a recovery potential of the cortico-thalamic system. We aimed to validate our previous findings in an independent, prospective cohort. Design/Methods: We prospectively enrolled 53 comatose post-cardiac arrest patients and assessed key clinical variables and outcomes (CPC). In patients with BSP (n=17), additional quantitative EEG analyses were performed using multi-taper methods. Burst and suppression periods were analyzed separately using previously published methods. Statistical analysis was performed using Mann-Whitney U test (continuous data) and Fisher’s exact test (categorical data). Results: Patients with BSP (n=17) and without BSP (n=36) did not significantly differ in most assessed clinical variables. In all 3 patients with BSP and favorable outcomes (CPC of 2), a prominent intra-burst theta (~4–7 Hz) peak was persistently present during BSP and/or the peak intra-burst frequency increased over time. In 7/14 patients with unfavorable outcomes (CPC 3–5) and BSP had featureless, flat spectra concentrating in low frequencies ( Conclusions: Prominent and persistent theta (~4–7Hz) peak or increasing intra-burst spectral peak frequency after anoxic brain injury may index a recovery potential. In the context of previous studies, our results emphasize the importance of optimizing metabolic substrate availability and stimulating the cortico-thalamic system during recovery from post-CA coma. Disclosure: Dr. Sehgal has nothing to disclose. Dr. Qing has nothing to disclose. Dr. Schiff has nothing to disclose. Dr. Forgacs has nothing to disclose.