Chronic inflammation in the myocardium of patients with clinically suspected dilated cardiomyopathy.

Dilated cardiomyopathy continues to be an etiologically unknown heart muscle disease. Recent clinical and experimental data have suggested a causal relation to viral myocarditis. The clinical diagnosis, however, is unspecific, and diagnostic yield of the histologic evaluation of endomyocardial biopsies by light microscopy according to the Dallas classification is poor. The authors analyzed the biopsy specimens of 120 patients with suspected dilated cardiomyopathy by immunohistologic methods to obtain a more sensitive and specific identification and quantification of infiltrating lymphocytes, indicating an activated immunologic process within the myocardium. Increased lymphocytic infiltrates and inflammatory endothelial activation were demonstrated in patients with clinically suspected dilated cardiomyopathy. These findings are associated with the often seen progression of ventricular dysfunction. Further studies are necessary to prove whether these immunohistologically positive patients will improve under immunosuppressive therapy.