Immune-mediated and autoimmune myocarditis: clinical presentation, diagnosis and management

According to the current WHO classification of cardiomyopathies, myocarditis is an inflammatory disease of the myocardium and is diagnosed by endomyocardial biopsy using established histological, immunological and immunohistochemical criteria; it may be idiopathic, infectious or autoimmune and may heal or lead to dilated cardiomyopathy (DCM). DCM is characterized by dilatation and impaired contraction of the left or both ventricles; it may be idiopathic, familial/genetic, viral and/or immune. The diagnosis of DCM requires exclusion of known, specific causes of heart failure, including coronary artery disease. On endomyocardial biopsy, there is myocyte loss, compensatory hypertrophy, fibrous tissue and immunohistochemical findings consistent with chronic inflammation (myocarditis) in 30-40 % of cases. In a patient subset, myocarditis and DCM represent the acute and chronic stages of an inflammatory disease of the myocardium, which can be viral, post-infectious immune or primarily organ-specific autoimmune. Here, we review the clinical presentation, etiopathogenetic diagnostic criteria, and management of immune-mediated and autoimmune myocarditis.