HISTOPATHOLOGY OF ENDOMYOCARDIAL BIOPSIES FROM PATIENTS WITH IDIOPATHIC CARDIOMYOPATHY; QUANTITATIVE EVALUATION BASED ON MULTIVARIATE STATISTICAL ANALYSIS
To evaluate the histological changes in endomyocardial biopsies from 121 patients with idiopathic cardiomyopathy, quantitation of histological findings was performed and analyzed by univariate and multivariate statistical analysis. Disarray of myofibers, myofiber hypertrophy, scarcity of myofibrils, nuclear changes, vacuolization, proliferation of collagen fibers, endocardial thickening, interstitial edema, cell infiltration, fatty infiltration and basophil degeneration were graded in 5 degrees (- to 4+) or 2 degrees (- or +) depending upon the severity and the extent of each finding. The univariate analysis of the graded histological findings revealed no remarkable difference between the biopsies from HCM [hypertrophic cardiomyopathy] and CCM [congestive cardiomyopathy] patients, except for nuclear changes, which were more prevalent in CCM (P < 0.05). In the categorical principal component analysis of the first 6 histological findings, 3 principal components were extracted. The 1st principal component was characterized by all 6 histological findings, the 2nd by vacuolization and proliferation of collagen fibers and the 3rd by hypertrophy of myofibers. The mean values of the 1st principal scores indicated that, in LVB [left ventricular biopsy] or R[right]VB histological changes were more severe in CCM than in HCM, and in fatal cases than in survivors. The 2nd principal scores indicated that fatal cases had more collagenosis but less severe vacuolization than survivors. The histological findings in RVB appeared to be significantly correlated (r = 0.41, P < 0.05) with those in LVB obtained from the same heart, but some differences were noted; myofiber hypertrophy and vacuolization were prominent in LVB than in RVB.