To determine if prophylactic administration of amiodarone for 72 hours in critically ill patients admitted after an OHCA with shockable rhythm, with a confirmed or a presumed cardiac cause, decreases the incidence of a composite endpoint of 30-day (starting from inclusion) all-cause mortality and/or severe in-hospital ventricular arrhythmia recurrence (ventricular fibrillation and/or ventricular tachycardia requiring intervention including re-arrest)

Inclusion Criteria:

1. Patient aged ≥ 18 years
2. Admitted in intensive care unit
3. Out-of-hospital cardiac arrest with initial shockable rhythm
4. Presumed cardiac or unknown cause
5. Delay between ROSC and screening for randomisation < 6 hours
6. Informed consent from the patient or a surrogate or deferred consent
7. Affiliated to or benefiting from a social insurance

Exclusion Criteria:

1. Cardiac arrest secondary to an extra-cardiac cause (suspected or confirmed)
2. Indication for amiodarone decided by the physician at ICU admission
3. No central venous catheter available for continuous infusion of amidoarone
4. Thyroid disease under treatment
5. History of cardiac conduction disorders, not treated by permanent pacemaker
6. Any contra indication to amiodarone treatment
7. Refractory ventricular arrhythmia or electrical storm
8. Need for veno-arterial extracorporeal membrane oxygenation (VA-ECMO) at admission
9. Known limitations in therapy and Do Not Resuscitate-order
10. Moribund patient due to pre-arrest history (estimated life expectancy < 3 months)
11. Pregnant or breastfeeding women
12. Patient needing a nadolol treatment due to QT long syndrome or catecholaminergic polymorphic ventricular tachycardia
13. Patient with known pulmonary fibrosis
14. Patient with known interstitial lung disease