[Immunosuppressive therapy of myocarditis?].

Clinical and experimental data suggest that autoimmunological mechanisms may play an important role in the pathogenesis of postmyocardial cardiomyopathy. This may be due to the viral infection itself, or may be induced by persistence of the virus. On this basis immunosuppressive therapy aimed at preventing the progression of myocarditis to dilated cardiomyopathy is discussed. Apart from the clinical signs of myocarditis, which are usually not specific, the diagnosis of acute myocarditis should be enabled by the histological examination of endomyocardial biopsies. In accordance with the Dallas criteria the histological diagnosis of acute myocarditis is defined by the presence of inflammatory cells in the myocardium associated with myocyte necrosis and degeneration of adjacent myocytes. This morphology, however, is only seen within the first seven to ten days of the acute stage of the disease. Later, most cases of clinically suspected acute myocarditis are histopathologically consistent with the diagnosis of "borderline myocarditis" 1 h according to the Dallas classification. Although endomyocardial biopsies have markedly improved diagnostic possibilities, the diagnosis of myocarditis by light microscopy has its limitations. Thus, interobserver variability in the interpretation of biopsy samples remains high, and divergent frequencies of reported positive biopsies have continued to be published. Mainly the differentiation of infiltrating mononuclear cells from interstitial fibroblasts or pericytes is visually difficult. New immunohistochemical methods were therefore introduced to improve the specificity and sensitivity of the histological diagnosis. Using monoclonal antibodies against cell surface markers from lymphocytes (CD3, CD4, CD8) the identification, characterization and quantification of lymphocytic infiltrates in the myocardium was improved very significantly. Furthermore, the use of monoclonal antibodies against MHC-class-I and class-II-antigens provides further information about the immunological status of the myocardium. In conclusion, the use of these new immunohistological methods offers the possibility of establishing immunological criteria in addition to histological parameters permit a more accurate diagnosis and a better understanding of immune mechanisms possibly involved in the pathogenesis of myocarditis and dilated cardiomyopathy. Since the introduction of endomyocardial biopsies in the diagnosis of myocarditis several papers have reported trials of immunosuppressive therapy in histologically-proven myocarditis. However, none of these studies were randomised, and only a limited number of patients were treated. Neither the primary diagnosis of myocarditis nor the histology, evaluating the course of the disease was well defined, and therefore different from one study to another. Moreover, the regimens so far used for immunosuppressive therapy were not standardized, making it impossible to compare the various studies.(ABSTRACT TRUNCATED AT 400 WORDS)