Moderate hypothermia for postarrest with nonshockable rhythm: HYPERION

  • Lascarrou JB & al.
  • N Engl J Med
  • 2 oct. 2019

  • de Jenny Blair, MD
  • Clinical Essentials
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  • Patients with cardiac arrest arising from nonshockable rhythms (asystole or pulseless electrical activity) might benefit from moderate therapeutic hypothermia (MTH).
  • This trial’s main result was marginally significant.

Why this matters

  • Hypothermia is recommended for patients in persistent coma after resuscitated out-of-hospital cardiac arrest. 
  • Several retrospective case series examining it for the subgroup with nonshockable rhythm have had variable conclusions.
  • Nonshockable rhythms are the most common type in patients with cardiac arrest and carry a poor prognosis.

Key results

  • MTH vs normothermia:
    • 90-day survival with favorable neurologic outcome:
      • 10.2% (29/284) vs 5.7% (17/297);
      • Difference, 4.5% (95% CI, 0.1-8.9; P=.04).
    • 90-day mortality:
      • 81.3% vs 83.2%;
      • Difference, −1.9% (95% CI, −8.0 to 4.4).
    • Similar rates of mechanical ventilation duration, ICU length of stay.
    • Similar adverse event rates. 

Study design

  • Open-label, multicenter, randomized controlled HYPERION trial (n=581).
  • Participants were adults experiencing coma after resuscitation from cardiac arrest because of nonshockable rhythm from any cause.
  • They were randomly assigned to undergo MTH (33ºC in the first 24 hours) vs normothermia.
  • Outcomes: 90-day survival with favorable neurologic outcome.
  • Funding: French Ministry of Health; Center Hospitalier Départemental Vendée; Laerdal Foundation.


  • Outcome change in 1 patient would render primary outcome difference insignificant.
  • Some hyperthermia occurred in control group.