DECREASED CONCENTRATION OF MYOFIBRILS AND MYOFIBER HYPERTROPHY ARE STRUCTURAL DETERMINANTS OF IMPAIRED LEFT-VENTRICULAR FUNCTION IN PATIENTS WITH CHRONIC HEART-DISEASES - A MULTIPLE LOGISTIC-REGRESSION ANALYSIS

Objectives. The aim of this study was to perform a multiple logistic regression analysis to identify independent structural determinants of impaired left ventricular function. Background. The association between contractile failure and structural alterations of the myocardium has been demonstrated in several studies, and multiple interactions between myocardial structure and cardiac performance are likely. Methods. Morphometric data assessed from 130 left ventricular biopsy specimens were analyzed. The endomyocardial specimens were obtained from 57 patients with normal coronary arteries (17 with normal left ventricular ejection fraction and 40 with impaired left ventricular function [dilated cardiomyopathy]), 15 patients with hypertrophic cardiomyopathy and 32 patients with aortic valve disease. Transmural biopsy specimens were assessed in 6 donor hearts before heart transplantation and in 20 patients with left anterior descending coronary artery disease whose specimens were obtained from the left ventricular anterior wall during aortocoronary bypass surgery. Global or regional left ventricular function was evaluated from left cineventriculograms. The volume fraction of cardiac fibrous tissue, intracellular volume fraction of myofibrils, volume fraction of myofibrils related to myocardial tissue (including fibrosis) and myofiber diameters were determined from semithin sections of the biopsy specimens with the use of tight microscopic morphometry. Results. Multiple logistic regression analysis revealed decreased volume fraction of myofibrils (p < 0.005) and increased fiber diameter (p < 0.002) as independent determinants of impaired left ventricular function. Conclusions. These data indicate that, independent of the underlying heart disease, both decreased concentration of contractile proteins and myocyte hypertrophy are independently associated with impaired left ventricular function.