Cardiac arrest is at present a major cause of mortality as well as a cause of disability for the surviving victims.In Europe, every year counts as 300,000 cardiac arrests responsible for 250,000 deaths. Thus, less than 20 % of patients discharged home with impaired quality of life associated with symptoms of tiredness, stress, anxiety. The prognosis is related to the initial cardiac rhythm present during the initiation of resuscitation. Recent progress in the improvement of mortality and neurological outcome has been achieved over the last decade thanks to the systematic implementation of a period of targeted temperature control between 32 and 34 ° C in patients who benefited from the realization of at least one electrical external shock.

There are theoretical and clinical arguments to think that achieving the same way a period of targeted temperature control between 32 and 34 ° C in patients treated for cardiac arrest with a non- shockable rhythm on arrival can also benefit from this procedure. However other arguments are against this hypothesis including an increase in the risk of infection , worsening of the patient's hemodynamic status with no benefit to him. To answer this question, we conduce a randomized multicenter study testing the potential improvement of neurological outcome through this procedure targeted temperature control between 32.5 and 33.5 ° C in these patients.

NSE-Ancillary Study of HYPERION Trial will determine impact on neurospecific enolase (brain biomarker) of two temperature target for targeted temperature management (33°C or 37°C) after cardiac arrest in non-shockable rhythm.

Inclusion Criteria:

• Cardiac arrest in nonshockable rhythm and
• Glasgow Coma Scale score ≤8. In patients receiving sedative therapy at ICU admission, the Glasgow Coma Scale score assessed by the emergency physician just before sedative therapy initiation is used.
• Patient must be randomized in a center which participate in the ancillary study.

Exclusion Criteria:

• No-flow time >10 min (time from collapse to initiation of external cardiac massage);
• Low-flow time >60 min (time from initiation of external cardiac massage to return of spontaneous circulation).
• Major hemodynamic instability (defined as a continuous epinephrine or norepinephrine infusion at a flow rate >1 μg/Kg/min)
• Time from cardiac arrest to study inclusion >300 min
• Moribund patient
• Child C cirrhosis of the liver
• Age <18 years
• Pregnant or breastfeeding woman
• Correctional facility inmate
• Previous inclusion in another randomized clinical trial on cardiac arrest with day-90 neurological outcome as the primary endpoint
• Patient without health insurance
• Decision by the patient or next of kin to refuse the study