Inclusion Criteria:  Age >= 18 years  Septic shock since a maximum of 72 hours, defined by the association of the following criteria:  Documented or suspected infection, with initiation of antibiotic therapy Initiation of vasopressors (norepinephrine, epinephrine) for at least 1 hour and at most 72 hours  Invasive mechanical ventilation NOSVA with heart rate ≥ 110 bpm lasting 5 minutes or more Written informed consent (patient, next of skin or emergency situation) Affiliation to a social security system  Exclusion Criteria:  Exclusion Criteria :  Refractory shock defined by a dose of noradrenaline BASE or adrenaline BASE > 1.2 µg/kg/min Cardiac surgery or cardiac transplant in the previous month Aortic or mitral mechanical prosthesis, significant mitral stenosis (mitral surface < 1.5 cm2) Congenital heart disease other than bicuspid aortic valve, atrial defect or patent foramen ovale. History of supraventricular arrhythmia before septic shock NOSVA lasting at most 36 hrs (or 24 hrs with vasopressors) Electrical cardioversion or use of amiodarone, other antiarrhythmic, or drug inducing bradycardia (beta-blockers, bradycardic calcium channel blocker, digitalis, flécaïnamide) in the previous 6 hours before inclusion Contraindication to amiodarone: history of serious adverse event related to amiodarone, history of lung disease related to amiodarone, history of hyperthyroidism related to amiodarone, PR interval > 240 ms, severe sinus node dysfunction with no pacemaker, 2°/ 3° atrioventricular block with no pacemaker, QTc>480 ms, known or treated hyperthyroidism, hypersensitivity to iodine, amiodarone or to any of the excipients, severe hepatocellular insufficiency (prothrombin rate <20%), diffuse Interstitial Lung Disease. Kalemia < 3 mmol/L Pregnant or breast feeding women Moribund patient or death expected from underlying disease during the current admission; Patient deprived of liberty and persons subject to institutional psychiatric care Participation to another interventional trial on septic shock and/or arrhythmic disease