Ultrastructural morphometric analysis of endomyocardial biopsies. Idiopathic dilated cardiomyopathy, anthracycline cardiotoxicity, and normal myocardium.

Anthracycline cardiotoxicity has been regarded as a model of idiopathic dilated cardiomyopathy, and similar histopathologic changes have been described in both. Our purpose was to quantify these changes, using computer-assisted ultrastructural morphometry, and compare them with normal myocardium. Right ventricular endomyocardial biopsies were taken from 10 patients with anthracycline cardiotoxicity (AC), 10 patients with idiopathic dilated cardiomyopathy (CM), and 10 disease-free transplant donor heart controls (C). Mean myocyte width (corrected for sarcomere length) was significantly greater in CM (29.3 microns +/- 7.2) than in AC (19.2 +/- 3.2) or C (20.3 +/- 3.4). Mean nuclear area was significantly greater in CM (88.7 microns 2 +/- 27.1) than in AC (54.2 +/- 15.3) or C (45.0 +/- 9.2). Nuclear form factor (corrected for sarcomere length) was significantly lower (indicating a more irregular outline) in CM (0.28 +/- 0.09) than in AC (0.46 +/- 0.06) or C (0.36 +/- 0.04). Mean mitochondrial area was significantly smaller in CM (0.30 microns 2 +/- 0.05) than in C (0.35 +/- 0.05), but differences between AC (0.35 +/- 0.09) and the other groups were not significant. These results suggest that anthracycline cardiotoxicity is not, quantitatively, a faithful model of idiopathic dilated cardiomyopathy.