Inclusion Criteria:  Age ≥18 years OHCA of presumed cardiac cause Sustained ROSC Unconsciousness (Glasgow coma scale <8) after sustained ROSC  Exclusion Criteria:  Conscious patients (obeying verbal commands) Females of childbearing potential (unless a negative HCG test can rule out pregnancy within the inclusion window) In-hospital cardiac arrest OHCA of presumed non-cardiac cause e.g. after trauma or dissection/rupture of major artery or cardiac arrest caused by initial hypoxia (i.e. drowning, suffocation, hanging). Known bleeding diathesis (medically induced coagulopathy (e.g. warfarin, NOAC, clopidogrel) does not exclude the patient) Suspected or confirmed acute intracranial bleeding Suspected or confirmed acute stroke Unwitnessed asystole Known limitations in therapy and Do Not Resuscitate-order Known disease making 180 days survival unlikely Known pre-arrest cerebral performance category 3 or 4 >4 hours (240 minutes) from ROSC to screening Systolic blood pressure <80 mmHg in spite of fluid loading/vasopressor and/or inotropic medication/intra-aortic balloon pump/axial flow device Temperature on admission <30°C