Diagnosis and Classification of Primary Myocardial Disease with the Aid of Endomyocardial Biopsy

By utilizing the endomyocardial biopsy, such diseases as myocarditis, myocardial sarcoidosis or giant cell myocarditis, and glycogen storage disease could be excluded as secondary myocardial disease. Those cases of clinically diagnosed primary myocardial disease were classified into three major groups according to their histopathological patterns. They are 1)Myocardial hypertrophy, 2) Myocardial degeneration or fibrosis, and 3) Endocardial thickening. 2. Accordingly, 125 biopsied cases which were diagnosed as primary myocardial disease could be differentiated into our classification. A: I) Familial, II') Suspected familial, III) Nonfamilial B: I) Endocardial fibroelastosis, II) Idiopathic cardiomyopathy a. Myocardial hypertrophy. b. Myocardial degeneration or fibrosis. c. Endomyocardial disease. d. Undetermined. III) Postpartal heart disease. IV) Suspected secondary cardiomyopathy. 3. Studies in each groups disclosed the following results (a) In the hypertrophic group; high incidence (37.7%) of the proven and those of strongly suspective familial occurrence was noteworthy. In high percentage, electrocardiographic evidences of hypertrophy, ST.T change, and abnormal Q waves were also noted. The cases could be divided into obstructive and non-obstructive form according to their hemodynamic features. How-ever, 7 cases were considered to be intermediate form because of the variability of the hemodynamic and angiocardiographic findings. The biopsies from the obstructive and intermediate form often revealed abnormally hypertrophic myocardial fibers with abundant glycogen. It is considered that the obstructive cardiomyopathy is not a different disease but one of the extreme form of the hypertrophic type cardiomyopathy and cannot be clearly differentiated from those of non-obstructive form. It is suggested that the hypertrophic type is that of endogenous nature. (b) In cases of degenerative or fibrotic type; rather lower incidence (10.6%) of familial occurrance, and high incidence of electrocardiographic conduction disturbances and of ST.T changes were noteworthy. It is speculated that this group may be of exogenous nature. (c) In those cases in which endocardial thickening was pre-dominant, it was assumed that they are secondarily developed lesions to either hypertrophic or degenerative or fibrotic type cardiomyopathy. Clinical pictures were those of mixted type of the two. Infantile endocardial fibroelastosis was considered to be of different nature. It is concluded that the application of the endomyocardial biopsy will give a potential value in making a more detailed clinical diagnosis of primary myocardial disease as well as recognizing the disease process. This study was supported by Asahi Shinbun academic research grant (Asahi Gakuzyutsu Shourei-kin) in the year of 1969-1970.