Defective myocardial carnitine metabolism in congestive heart failure secondary to dilated cardiomyopathy and to coronary, hypertensive and valvular heart diseases

Abstract

Reduced myocardial carnitine concentrations in the explanted heart and elevated plasma levels have been found in patients undergoing heart transplant for end-stage congestive heart failure (CHF). To evaluate a possible loss of myocardial carnitine in less severe stages of CHF, total myocardial carnitine levels were compared in right ventricular endomyocardial biopsies from 28 patients with mild, moderate and severe dilated cardiomyopathy, 8 patients with CHF of different origin and 13 normal control subjects. If possible, free myocardial carnitine and free and total plasma carnitine were also determined. For the first time, myocardial carnitine levels have been measured in endomyocardial biopsies from 13 normal human hearts (control values: 9.9 ± 0.8 nmol/mg noncollagen protein). In comparison with these control values, total myocardial carnitine was significantly reduced in patients with dilated cardiomyopathy (6.1 ± 0.5 nmol/mg non-collagen protein, p < 0.0001), and CHF of other origins (6.6 ± 1.1 nmol/mg noncollagen protein, p < 0.02). Free myocardial carnitine concentrations in dilated cardiomyopathy (4.6 ± 0.4 nmol/mg non-collagen protein) and CHF of different origin (4.4 ± 0.5 nmol/mg noncollagen protein) were also significantly different from control values (control values: 9.7 ± 0.7 nmol/mg noncollagen protein, p < 0.0001 and p < 0.005 for both groups). The loss of free and total myocardial carnitine was comparable in dilated cardiomyopathy and CHF due to other diseases. In contrast, plasma free and total carnitine levels in the CHF patients were significantly elevated (67 ± 5.5 μmol/liter, control values 41 ± 3.7 μmol/liter, p < 0.005). Alterations in myocardial carnitine metabolism represent nonspecific biochemical markers in CHF with yet unknown consequences for myocardial function.