The role of biopsy in the diagnosis of myocarditis.

Reference to the background of myocarditis since the early nineteenth century has been made to emphasize the problem of diagnosis of this condition which has been largely overcome by the introduction of the bioptome and morphological evaluation of the fresh endomyocardial biopsies obtained by these means. A definition and classification into active, healing and healed phases has been provided and constitutes a rational approach to therapy with corticosteroids and immunosuppressive agents. The observation that myocarditis is evident in biopsy tissue from patients suspected with dilated cardiomyopathy and additional virological and immunological investigations have shed light on a possible pathogenetic mechanism which in some patients with this condition is an infectious immunological process. In addition, when myocarditis in the active or early healing phases is found, it has been shown that therapy is beneficial to the patient. Myocarditis is also the initial morphological expression of endomyocardial disease associated with eosinophilia. The eosinophils are in addition morphologically abnormal in the form of degranulation. Examination of blood films and endomyocardial biopsies has defined the earliest form of this disease process and early treatment can also now be instituted. This up-to-date overview of our present state of knowledge has repeatedly demonstrated that biopsy examination in the diagnosis of myocarditis plays a vital role.