Methylprednisolone in chronic myocarditis

The aetiology of dilated cardiomyopathy is unknown. Recent clinical and experimental data have suggested a temporal relationship with viral myocarditis. The clinical diagnosis, however, is non-specific. The evaluation of endomyocardial biopsies by light microscopy and their histological classification according to the Dallas criteria is limited by the difficulty in differentiating and quantifying infiltrating inflammatory lymphocytes from non-inflammatory interstitial cells. Using immunohistological methods that allow better identification and quantification of infiltrating lymphocytes and that also provide evidence for an activated immunological process within the myocardium, myocarditis was diagnosed on endomyocardial biopsy in 48 of 130 patients (37%). On the basis of both haemodynamic and immunohistological findings, 31 of these patients were selected for immunosuppressive treatment. After a 6-month treatment period with 6-methylprednisolone, 23 patients showed an improvement according to the NYHA classification. Lymphocytic infiltrates were abolished in 24 patients. Left ventricular systolic function was improved in 20 patients (64%) as indicated by an increased ejection fraction and stroke volume with a concomitant decrease of left ventricular end diastolic pressure. The three patients with severely impaired left ventricular function did not improve either clinically or histologically, whilst in four patients the clinical findings remained unchanged in spite of histological resolution of the inflammatory infiltrate in the myocardium. Our study suggests that immunosuppressive treatment in a subgroup of patients with dilated cardiomyopathy who have a continuing active immunohistologically proven inflammatory process results in a clinical haemodynamic and immunohistological improvement in 60-70% of the patients.