Histopathology of endomyocardial biopsies from patients with idiopathic cardiomyopathy; quantitative evaluation based on multivariate statistical analysis.

In order to evaluate the histological changes in endomyocardial biopsies from 121 patients with idiopathic cardiomyopathy, quantitation of histological findings was performed and analysed by univariate and multivariate statistical analysis. Several findings, i.e. (1) disarray of myofibers, (2) hypertrophy of myofibers, (3) scarcity of myofibrils, (4) nuclear changes, (5) vacuolization, (6) proliferation of collagen fibers, (7) endocardial thickening, (8) interstitial edema, (9) cell infiltration, (10) fatty infiltration and (11) basophile degeneration, were graded in five degrees (- to 4+) or two 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 and CCM pts, except for nuclear changes, which appeared to be more prevalent in CCM (p less than 0.05). In the categorical principal component analysis of the first six histological findings listed above, three principal components could be extracted. The first principal component was characterized by all six histological findings, the second by vacuolization and proliferation of collagen fibers, and the third by hypertrophy of myofibers. The mean values of the first principal scores indicated that, in either LVB or RVB histological changes were more severe in CCM than in HCM, and in fatal cases than in survivors. The second 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 less than 0.05) with those in LVB obtained from the same heart, but some differences were noted, myofiber hypertrophy and vacuolization being more prominent in LVB than in RVB.