RESTRICTIVE CARDIOMYOPATHY, ATRIOVENTRICULAR-BLOCK AND MILD TO SUBCLINICAL MYOPATHY IN PATIENTS WITH DESMIN-IMMUNOREACTIVE MATERIAL DEPOSITS

Objectives. We present clinical data and heart and skeletal muscle bio psy findings from a series of patients with ultrastructural accumulati ons of granulofilamentous material identified as desmin. Background. D esmin cardiomyopathy is a poorly understood disease characterized by a bnormal desmin deposits in cardiac and skeletal muscle. Methods. Clini cal evaluation, endomyocardial and skeletal muscle biopsy, light and e lectron microscopy and immunohistochemistry were used to establish the presence of desmin cardiomyopathy. Results. Six hundred thirty-one pa tients with primary cardiomyopathy underwent endomyocardial biopsy (EM B). Ultrastructural accumulations of granulofilamentous material were found in 5 of 12 biopsy samples from patients with idiopathic restrict ive cardiomyopathy and demonstrated specific immunoreactivity with ant i-desmin antibodies by immunoelectron microscopy. Immunohistochemical findings on light microscopy were nonspecific because of a diffuse int racellular distribution of desmin. All five patients had atrioventricu lar (AV) block and mild or subclinical myopathy. Granulofilamentous ma terial was present in skeletal muscle biopsy samples in all five patie nts, and unlike the heart biopsy samples, light microscopic immunohist ochemical analysis demonstrated characteristic subsarcolemmal desmin d eposits. Two patients were first degree relatives (mother and son); an other son with first-degree AV block but without myopathy or cardiomyo pathy demonstrated similar light and ultrastructural findings in skele tal muscle. Electrophoretic studies demonstrated two isoforms of desmi n-one of normal and another of lower molecular weight-in cardiac and s keletal muscle of the familial cases. Conclusions. Desmin cardiomyopat hy must be considered in the differential diagnosis of restrictive car diomyopathy, especially in patients with AV block and myopathy. Diagno sis depends on ultrastructural examination of EMB samples or light mic roscopic immunohistochemical studies of skeletal muscle biopsy samples . Familial desminopathy may manifest as subclinical disease and may be associated with abnormal isoforms of desmin. (C) 1998 by the American College of Cardiology.