Autoimmune myocarditis: a clinical entity.

In a case of myocarditis electron microscopic and immunoflourescent studies of a transmural myocardial biopsy specimen indicated an autoimmune process. Extensive inflammatory cell infiltration, immunoglobulin and complement deposition along the sarcolemma and in the interstitium, and capillary endothelial injury were found. After a short course of immunosuppressive therapy the inflammatory process was replaced by collagenous scarring and lymphocytic depletion; the blood vessels were then normal. Earlier therapy in such cases may be lifesaving.