Primary restrictive cardiomyopathy: clinical and pathologic characteristics.

Twenty-four patients with restrictive cardiomyopathy were identified at St. Thomas' Hospital during a 17-year period. All had endomyocardial biopsy, but in two patients the biopsy specimens were small and nondiagnostic. Seven patients had amyloidosis and five had other specific heart muscle diseases. The remaining 10 patients with primary restrictive cardiomyopathy had myocyte hypertrophy or interstitial fibrosis, or both. Patients with primary restrictive cardiomyopathy presented earlier but survived longer after presentation than did those with amyloidosis. In each group, survival after cardiac catheterization was related to cardiac index but not to filling pressures. Primary restrictive cardiomyopathy was associated with complete heart block in four patients, two of whom had skeletal myopathy. One had a family history of dominantly inherited skeletal myopathy. Primary restrictive cardiomyopathy was present in a mother and daughter. Two other patients had a family history of heart failure, sudden death or complete heart block, alone or in combination, at a young age. Restrictive hemodynamics and complete heart block were present in patients even in the absence of significant fibrosis. The data suggest that primary restrictive cardiomyopathy may be a distinct myopathy with dominant inheritance and incomplete penetrance that is expressed morphologically as myocyte hypertrophy and interstitial fibrosis. Skeletal myopathy may be associated with the cardiomyopathy.