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Rhythmic and periodic electroencephalography (EEG) patterns, particularly generalized periodic discharges (GPDs), frequently occur in patients following return of spontaneous circulation (ROSC) after cardiac arrest. These patterns, particularly when associated with persistent myoclonus, suggest a much higher, although not certain, likelihood of poor prognosis. Antiseizure medications and anesthetics frequently are used in this setting, but whether suppressing GPDs, seizures, and other rhythmic patterns improves neurological outcome is unclear.
In this pragmatic, open-label trial conducted at 11 Dutch and Belgian intensive care units, 172 comatose survivors of cardiac arrest receiving targeted temperature management were enrolled. The 88 patients in the treatment arm received protocolized therapy with antiseizure and sedative medications titrated to completely suppress the EEG patterns, which was achieved for 24 hours postrandomization in 73%. Approximately 80% of patients had GPDs, 10% had electrographic seizures, and 62% experienced myoclonus. Sedation to suppress myoclonus was permitted in the control group. A poor neurological outcome occurred in a similarly high proportion of the two groups (92% of controls vs. 90% of treatment patients).
Ruijter BJ et al. Treating rhythmic and periodic EEG patterns in comatose survivors of cardiac arrest. N Engl J Med 2022 Feb 24; 386:724. (https://doi.org/10.1056/NEJMoa2115998)
Comment
This well-conducted trial suggests that attempted suppression of rhythmic and periodic EEG patterns does not improve neurological outcome in the study population. The high prevalence of clinical myoclonus and GPDs is consistent with enrolled patients having severe hypoxic-ischemic injury with a very high likelihood of poor prognosis. Consequently, clinicians should be cautious in generalizing these study results to the entire population of comatose survivors of cardiac arrest. An additional major limitation is the high incidence of withdrawal of life-sustaining treatment, which occurred in 77% in both groups; many had care withdrawn less than 72 hours after ROSC. Current guidelines strongly recommend a minimum 72-hour observation period to assess for neurological recovery (Circulation 2020; 142:Suppl 2:S337; and Intensive Care Med 2014; 40: 1816). Withdrawal of care and self-fulfilling prophecies may have played a role in patient outcomes.