To date, the effects of SARS-Cov-2 (Covid-19) on the myocardium and the role it plays in the evolution towards an acute myocarditis are badly understood. The current pandemic of this emerging virus is an opportunity to assess the proportion of acute myocarditis attributable to SARS-Cov-2(Covid-19) and to assess the clinical, biological and imaging presentations, by means of a national prospective multicentre hospital registry of cases of acute myocarditis.

Although research on the subject has only recently started developing, the links have already been described between SARS-Cov-2 infection, the severity of the clinical status, and the presence of risk factors or a history of cardiovascular disease (hypertension, diabetes, stroke, etc.). Additionally, depending on the series and definition used for cardiac injury (troponin elevation and/or natriuretic peptides), this concerns 7-29% of patients with a clear predominance in severe patients. The mechanisms behind these troponin elevations and cardiac injury are likely to be multiple and variable depending on clinical presentation,severity and patient history. A significant association was found between troponin elevation, and that of CRP and NtproBNP, suggesting an inflammatory part to this cardiac damage. As with other coronaviruses, SARS-Cov-2 infection can cause massive release of proinflammatory cytokines which can lead to inflammation of the vascular wall. This can be the cause of true instability or even rupture of plaque(type1 infarction) but can also be responsible for tissue hypoxia without rupture of plaque causing myocardial pain (infarction type 2). In addition, there may be areal myocardial inflammation causing acute myocarditis, secondary to the cytokine storm or direct damage to the myocardium by the virus itself. In case of acute coronary syndrome presentation, a coronary exploration should be realized to highlight or eliminate a type 1 infarction, but it is clearly difficult to distinguish between a type 2 suffering (no viral attack direct but suffering from hypotension or hypoxia for example) and inflammatory myocardial damage with or without direct viral myocardial damage (myocarditis). In the context of the viral pandemic at Covid19, although few data exist,it is legitimate to consider the possibility of true arrays of acute inflammatory myocarditis or by direct viral attack which could thus modify the natural history and the prognosis of patients, thus justifying a dedicated diagnosis and treatment. The primary objective was to assess the proportion of positive SARS-Cov-2 cases among the patients included (hospitalized for acute myocarditis). During the study period, this proportion will be assessed at regular intervals, for example every month, or more frequently if the number of patients included varies substantially from one week to another. This will make it possible to trace a development curve for the entire period of the pandemic.

The secondary objectives were (1) to describe the clinical, biological and imaging characteristics of the acute myocarditis among the positive and negative SARS-Cov-2 patients of the myocarditis cohort; (2) to assess the short-term (30 days) and long-term (1 year) prognosis of the acute myocarditis among the positive and negative SARS-Cov-2 patients of the myocarditis cohort and (3) to identify the factors associated with a 30-day and 1-year prognosis of cases of acute myocarditis.

Inclusion Criteria:

• Patients treated in ICCU or ICU (polyvalent, surgical or medical), in one of the participating hospitals, for symptoms of acute myocarditis confirmed by a myocardial MRI and/or a CT scan and/or a myocardial biopsy. It seems important to include elderly patients who may be under guardianship or curatorship since these patients seem to present the most severe forms. Additionally, the populations most affected by viral myocarditis are generally adolescents and young adults,which justifies including them in the study too. Pregnant women are a population at potentially greater risk, particularly during the third trimester because of the neuro-hormonal changes inherent in pregnancy. This justifies trying to implement the investigator's knowledge through this observational study.

Exclusion Criteria:

• Refusal to participate.

Patients treated in ICCU or ICU (polyvalent, surgical or medical), in one of the participating hospitals