Pulse Corticosteroids Or/and Immunoglobulins to Treat Fulminant Myocarditis

Inclusion Criteria: * 1\. Fulminant myocarditis defined by * the acute illness (\<1 month from symptom onset), * hemodynamic compromise due to cardiogenic shock (confirmed by echocardiography) or electrical storm, * elevated plasma cardiac troponin \> twice normal value * need for hemodynamic support (inotropes or temporary mechanical circulatory support) for less than 72 hours in the absence of an ischemic cause or other pre-existing cardiomyopathies Noticeably, a coronary angiogram should be performed in patients ≥40 years of age when myocarditis has not been proven histologically. Besides, an endomyocardial biopsy will not be mandatory to fulfill the definition of fulminant myocarditis. 2\. Signed informed consent from the patient, a close relative or surrogate or a family member or a legal representative for minor patient. * Adult : According to the specifications of emergency inclusion, randomization without the close relative/surrogate consent could be performed if the patientis unable to give his/her consent and when the close relative/surrogate/family member are absent. Close relative/surrogate/family member consent will be asked as soon as possible after randomization. The patient will be asked as soon as possible to give his/her consent for the continuation of the trial when his/her condition will allow. * Minor : According to the specifications of emergency inclusion, randomization could be performed when legal representative are absent. Legal representative consent will be asked as soon as possible after randomization 3. Social security registration (AME excluded) Exclusion Criteria: * 1\. Age \<15 2. Pregnancy or breastfeeding or baby delivery \<6 months 3. Initiation of inotropes or temporary mechanical circulatory support \>72 hours 4. Resuscitation \>20 minutes (cumulative low-flow time \> 20 minutes ) 5. Pre-existing ischemic or dilated cardiomyopathy or Tako-Tsubo evaluated by echocardiography. 6\. Known systemic autoimmune disorder or other conditions requiring immunosuppression 7. Patients with peripheral eosinophilia (≥1000 G/L) 8. Myocarditis associated with anti-cancer immune checkpoint inhibitor agents 9. Active severe bacterial or fungal infectious disease 10. Patient moribund on the day of randomization, SAPS II \>90 11. Contraindication or allergies to corticosteroids or immunoglobulins or any components of the formulations or their excipients 12. Patients already on corticosteroids or receiving IVIG 13. Participation in another interventional study or being in the exclusion period at the end of a previous study. 14\. Patients with an uncontrolled psychotic condition Patients with known anti-IgA antibodies in line with the contraindications of methylprednisolone IV and of IVIg based products respectively