Figure 1. Representative CMR image and ³¹P MR spectra.

Representative axial MRI (right) of the chest of a 45-year-old woman (lying prone) who subsequently experienced an arrhythmic event. Yellow lines denote localized volumes from which ³¹P MRS spectra (left) were derived (arrows). The upper spectrum from the heart shows phosphocreatine (PCr), diphosphoglycerate (DPG), and the 3 phosphate resonances of ATP. The myocardial ATP was low (2.5 μmol/g wet wt) but PCr/ATP was normal (1.7) in this individual. The lower spectrum includes chest muscle and is shown for comparison but was not used in analysis.