Differential Diagnosis Myocarditis must be distinguished from other anomalies that present with signs and symptoms of acute cardiac failure early in life A variety of metabolic diseases may present with dilated cardiomyopathy in infancy, which should be excluded When the left coronary artery arises anomalously from the pulmonary trunk, the characteristic features are the electrocardiographic signs of an anterolateral myocardial infarction The diagnosis can be confirmed by echocardiography or by cardiac catheterization Enlargement of the heart and cardiac failure may also be caused by long-standing severe anemia Dilation of the heart may also occur as a secondary phenomenon in patients with systemic arteriovenous fistulas Autoimmune and Autoinflammatory Myocarditis Cardiac involvement in autoimmune and autoinflammatory diseases can comprise all components of the heart, including the pericardium, myocardium, endocardium, coronary arteries, and valves The clinical presentation of autoimmune myocarditis is similar to that of infectious myocarditis Evaluation for autoimmune conditions should be done in patients who present with otherwise unexplained myocarditis Systemic Lupus Erythematosus In systemic lupus erythematosus, the myocardial lesions consist mainly of fibrinoid changes in the connective tissue with a cellular reaction Similar changes may affect the valves, notably the mitral and aortic valves The lesions may heal, leaving fibrous scars Libman and Sacks31 described the distinctive type of valvar and mural endocarditis that occurs in this condition It is characterized by verrucous lesions along the line of closure of the valves as well as along the ventricular surface of the leaflets extending onto the mural endocardium The disease involves many systems including the heart Cardiac manifestations may be the presenting feature of the disease.32