Rhythmic and periodic electroencephalographic (EEG) patterns that may reflect electrographic seizures have been reported in 10 to 35% of comatose patients after cardiac arrest. It has been suggested that the effects of antiseizure medication depend on the specific EEG pattern being treated. However, a recent study suggests that comatose survivors of cardiac arrest didn't benefit from intense treatment of seizure-alike activity on continuous electroencephalographic (EEG) monitoring.

The study findings were published in The New England Journal of Medicine on February 24, 2022.
Whether rhythmic and periodic EEG patterns should be treated with antiseizure medications to improve the neurologic outcome is unclear. Therefore, Dr Barry J. Ruijter and his team hypothesized that the use of antiseizure medication would reduce the incidence of a poor neurologic outcome at 3 months.
In the TELSTAR open-label trial, the researchers analyzed data from 172 comatose survivors of cardiac survivors and randomized them to stepwise antiseizure treatment (n=88) or standard care (n=84), with both groups receiving targeted temperature management. The major outcome assessed was the outcome was neurologic outcome according to the score on the Cerebral Performance Category (CPC) scale at 3 months, dichotomized as a good outcome (CPC score indicating no, mild, or moderate disability) or a poor outcome (CPC score indicating severe disability, coma, or death). They also assessed the mortality, length of stay in the intensive care unit (ICU), and duration of mechanical ventilation.
Key findings of the study:
Rhythmic or periodic EEG activity was detected in a median of 35 hours after cardiac arrest, in which the researchers observed 98 of 157 patients (62%) had myoclonus.
Upon analysis, they found that complete suppression of rhythmic and periodic EEG activity for 48 consecutive hours occurred in 49 of 88 patients (56%) in the antiseizure-treatment group and in 2 of 83 patients (2%) in the control group.
At 3 months, they noted that 79 of 88 patients (90%) in the antiseizure-treatment group and 77 of 84 patients (92%) in the control group had a poor outcome.
They observed that the mortality at 3 months was 80% in the antiseizure-treatment group and 82% in the control group.
However, they noted that the mean length of stay in the ICU and mean duration of mechanical ventilation were slightly longer in the antiseizure-treatment group than in the control group.
The author concluded, "In comatose survivors of cardiac arrest, the incidence of a poor neurologic outcome at 3 months did not differ significantly between a strategy of suppressing rhythmic and periodic EEG activity with the use of antiseizure medication for at least 48 hours plus standard care and standard care alone."
For further information:
DOI: 10.1056/NEJMoa2115998