Regional myocardial metabolism of high-energy phosphates in patients with coronary artery disease

To the Editor: Weiss et al. (Dec. 6 issue)¹ recently reported interesting changes in high-energy phosphate metabolism during exercise in patients with coronary artery disease, as measured by nuclear magnetic resonance (NMR) spectroscopy. A few critical remarks need to be added to their discussion and interpretation of results, however. The statement by the authors that “direct measurement of ischemia-induced metabolic change in human myocardium has been limited to invasive sampling of lactate and succinate in coronarysinus effluent” is incorrect. On the contrary, not only have intermediary metabolites been determined, but ATP catabolites, such as hypoxanthine, have also been directly sampled.