Cellular hypertrophy in cardiomyopathic patients is associated with lower creatine-stimulated mitochondrial respiration.

The mitochondrial respiration rate and morphometric indices in endomyocardial biopsy samples were measured in 43 patients with dilated cardiomyopathy selected in accordance to WHO criteria by endomyocardial biopsy studies after excluding of various forms of myocarditis, alcoholic cardiomyopathy and other specific diseases of the heart. A group of 13 patients with unusually high mean myocyte diameter, 30 +/- 4 microns, and nuclear size, 57 +/- 5 microns, was selected. The remainder of patients (n = 30) had significantly lower mean myocyte diameter and nuclear size, 23 +/- 3 and 42 +/- 6 microns, respectively, (p < 0.01). Creatine-stimulated elevation in mitochondrial respiration rate as measured in saponin-skinned fibers was found in the former group to be much lower (36 +/- 4%) as compared with the remainder (90 +/- 12%). Also, the former group of patients had higher left ventricular enddiastolic pressure and volume index with concomitantly decreased ejection fraction. The results indicate that marked nuclear and cellular hypertrophy is associated with lower creatine-stimulated mitochondrial respiration rate and more severe cardiac failure. They suggest that disorders in energy supply to myofibrils may be related to disturbances in cellular genetic apparatus.