The P-31-NMR stress test: An approach for detecting myocardial ischemia

P-31-NMR spectroscopy has the potential to assess myocardial damage directl y and noninvasively by ascertaining the relative abundances of phosphorus-c ontaining compounds relevant to metabolism under stress conditions. Decreas e in the PCr/ATP ratio during exercise is an indicator of the level of stre ss to which the myocardium is subject. This ratio will remain constant unde r mild to moderate exercise conditions in a healthy subject, but may show a precipitous decrease even under mild exercise when regions of the myocardi um are ischemic. The studies examined here indicate that cardiac patients w ith some forms of ischemia showed a PCr/ATP ratio decrease even under Light exercise, while no decrease was observed in patients whose heart disease w as known to be nonischemic. Hypertension and nonstenotic chest pain in wome n can, in some cases, produce a decrease in PCr/ATP ratio. Only the hyperte nsive patients showed a significant difference in the prestress PCr/ATP rat io when compared with controls. These studies suggest that P-31-NMR spectro scopy before and during mild exercise in the bore of the magnet can be a us eful indicator of the presence or absence of an ischemic component to myoca rdial disorder. (C) 2000 Biomedical Engineering Society. [S0090-6964(00)016 08-8].