Mild therapeutic hypothermia in the temperature range of 32º - 34ºC. improves survival in patients recovered from a ventricular fibrillation cardiac arrest. The same therapy is suggested with less evidence for asystole as first rhythm after cardiac arrest. The purpose of this study is to determine whether different temperature targets (32º vs 34º) may have different efficacy in the treatment of post-cardiac arrest patients. If successful, this pilot study will eventually form the basis for a larger, multicentric randomized clinical trial.

Patients admitted consecutively were potentially eligible for the study if they had a witnessed out-off hospital cardiac arrest (OHCA) apparently related to heart disease and an interval of <60 minutes from collapse to return of spontaneous circulation (ROSC). Additional inclusion criteria were:

1. Age >18 years.
2. Initial registered rhythm of a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia) or asystole.

Exclusion criteria were:

1. Known pregnancy
2. Glasgow Coma Scale score after ROSC >8.
3. Cardiogenic shock (a systolic blood pressure of <80 mm Hg despite inotrope infusion >30 minutes).
4. Other nonshockable rhythms (pulseless electric activity).
5. Terminal illness present before the OHCA.
6. Possible causes of coma other than cardiac arrest (drug overdose, head trauma, or cerebrovascular accident).

Inclusion Criteria:

• Age > 18
• Resuscitated patients from a cardiac arrest with first rhythm of ventricular fibrillation or asystole
• Witnessed cardiac arrest
• Estimated delay between cardiac arrest and advanced resuscitation < 20 min.
• Resuscitation time from first contact to recovery of spontaneous circulation < 60 min.
• Hemodynamic stability (Mean blood pressure [BP] >60 mmHg), with or without inotropic drugs, before randomization
• Glasgow coma score <9 without sedation before randomization

Exclusion Criteria:

• Pregnant women or suspected pregnancy or fertile women without a negative pregnancy test
• Suspected non-cardiac arrest caused coma
• Electrical instability (uncontrollable life-threatening arrhythmias)
• Hemodynamic instability (Mean BP ≤60 mmHg), refractory to volume infusion or inotropic drugs
• Refractory hypoxemia (saturation <85% with FiO2=100%)
• Previous known terminal illness
• Active bleeding or known coagulopathy
• Opposition from patient's family to enter the study