Imaging cardiac metabolism in heart failure: the potential of NMR spectroscopy in the era of metabolism revisited.

Nuclear magnetic resonance (NMR) spectroscopy remains an extremely powerful technique for investigating abnormalities in the failing heart. The nondestructive nature of the technique allows the response to physiological, pathophysiological and pharmacological interventions to be studied within the same heart. Phosphorus-31 NMR has provided a gold standard over the past two decades for assessing the myocardial energy status both in vitro and in vivo. Carbon-13 isotopomer analysis is emerging as a direct way to monitor metabolic pathways and, in particular, investigate adaptations in energy provision in pathophysiological conditions. Using models of cardiac hypertrophy and heart failure, we investigated the sequences of changes in substrate oxidation in relation to function using 13C methods. The changes in metabolism modify the balance between energy provision and utilisation, and thus play a deleterious role in the progression towards decompensated heart failure. The application of NMR spectroscopy (phosphorus-31 and carbon-13) to the study of integrated metabolism is an area of research which is now coming into its own. Together with other new technologies, NMR will contribute to our improved understanding of cardiac metabolism in situ, leading to more rapid advances in targeting new therapeutic end points.