Functional and histopathologic correlation in patients with dilated cardiomyopathy: an integrated evaluation by multivariate analysis.

To correlate left ventricular function and histologic features in patients with dilated cardiomyopathy, precise indexes of hemodynamics and semiquantitative histologic data were combined for multivariate analysis. Right endomyocardial biopsy was performed at the time of cardiac catheterization. Five hemodynamic indexes were used for functional assessment: ejection fraction, ratio of end-systolic stress to volume index, end-diastolic stress, time constant (T) of left ventricular pressure fall, and end-systolic stress. Six histologic findings (disarray of myofibers, hypertrophy of myofibers, scarcity of myofibrils, nuclear changes of myofibers, vacuolization of myofibers and proliferation of collagen fibers) were graded from (-) to (4+). Each finding was assigned to category (-) or (+) according to the absence or presence of significant abnormality. Ordinary statistical analysis revealed that, although ejection fraction was lower in category (+) for proliferation of collagen fibers, ratio of end-systolic to volume index was reduced for category (+) of hypertrophy of myofibers. A significant correlation was present between hypertrophy of myofibers and proliferation of collagen fibers by Spearman rank correlation. When principal component analysis was applied to the hemodynamic data, two principal components could be extracted. Fisher's discriminant analysis could clearly differentiate two categories (-) and (+) in the semiquantitative histologic finding of proliferation of collagen fibers. The analysis indicated that contractility was reduced with elevated afterload in that category (+). Thus, proliferation of collagen fibers may play a pivotal role in deteriorating contractility in patients with dilated cardiomyopathy.