HYPERION: Moderate Therapeutic Hypothermia Shows Survival Benefit in Some

Moderate therapeutic hypothermia at a slightly colder temperature for 24 hours was linked with a higher survival rate in patients with coma resuscitated from nonshockable cardiac arrest, a new study indicates.

“Moderate therapeutic hypothermia is currently recommended to improve neurologic outcomes in adults with persistent coma after resuscitated out-of-hospital cardiac arrest,” the researchers wrote in their study abstract. “However, the effectiveness of moderate therapeutic hypothermia in patients with nonshockable rhythms (asystole or pulseless electrical activity) is debated.”

Researchers for the Therapeutic Hypothermia After Cardiac Arrest on Nonshockable Rhythm (HYPERION) study, an open-label, randomized, controlled study, sought to evaluate the efficacy of moderate therapeutic hypothermia in patients with nonshockable rhythms (defined as asystole or pulseless electrical activity). A total of 584 patients were randomized to either moderate therapeutic hypothermia (33°C during the first 24 hours) or targeted normothermia (37°C). All patients had comas, were admitted to the ICU after resuscitation from cardiac arrest with nonshockable rhythm. Three patients withdrew consent, leaving a total of 581 patients included in the final analysis). The study results were published in the New England Journal of Medicine.

According to the results, on day 90, a total of 29 of 284 patients (10.2%) in the intervention hypothermia group remained alive with a Cerebral Performance Score (CPC; score of 1 to 5, with higher value meaning greater disability) of 1 or 2, compared to 17 of 297 (5.7%) of patients in the normothermia group (difference, 4.5%; 95% CI, 0.1 to 8.9; P=0.04). The researchers also reported that mortality did not significantly differ between study groups at 90 days. The incidence of prespecified adverse events also did not differ between study groups.

“Among patients with coma who had been resuscitated from cardiac arrest with nonshockable rhythm, moderate therapeutic hypothermia at 33°C for 24 hours led to a higher percentage of patients who survived with a favorable neurologic outcome at day 90 than was observed with targeted normothermia,” the authors wrote in the abstract.