Altered myocardial high-energy phosphate metabolites in patients with dilated cardiomyopathy.

Myocardial high-energy phosphate metabolism in patients with dilated cardiomyopathy (DCM) of ischemic or idiopathic etiology was assessed at rest by one-dimensional phase-encoded 31P-nuclear magnetic resonance (NMR) spectroscopy studies performed in conjunction with 1H imaging in 20 patients with DCM and in 12 normal volunteers. The measured values of anterior myocardial phosphocreatine/beta-adenosine triphosphate (PCr/beta-ATP), corrected for partial saturation and contamination of the spectra by blood metabolites, averaged 1.80 +/- 0.06 (mean +/- SE) in normal volunteers and 1.46 +/- 0.07 in the patients overall, a highly significant (p less than 0.001) decrease. In patients with DCM accompanied by coronary artery disease (n = 9), the PCr/beta-ATP ratio averaged 1.53 +/- 0.07, while in those with DCM alone it was 1.41 +/- 0.12 (n = 11), a value that was not significantly different. There was no significant correlation (r = 0.34) between myocardial PCr/ATP ratio and left ventricular ejection fraction in patients. These studies demonstrate that myocardial PCr/ATP ratios are reduced at rest in human ischemic and idiopathic dilated cardiomyopathy.