PROTON-DECOUPLED MYOCARDIAL P-31 NMR-SPECTROSCOPY REVEALS DECREASED PCR P-I IN PATIENTS WITH SEVERE HYPERTROPHIC CARDIOMYOPATHY/

Disturbed myocardial energy metabolism may occur in patients with prim ary hypertrophic cardiomyopathy (HCM). A noninvasive way to gain insig ht into cardiac energy metabolism is provided by in vivo P-31 nuclear magnetic resonance (NMR) spectroscopy. P-31 NMR spectroscopy with prot on decoupling was performed in 13 patients aged 13-36 years with HCM o n a 1.5 T Magnetom with a double resonant surface coil. A 2D chemical shift imaging (CSI) sequence in combination with slice selective excit ation was used to acquire spectra of the anteroseptal region of the le ft ventricle (volume element: 38 mL). The chemical shifts of the phosp horus metabolites, intracellular pH(i), and coupling constants J(alpha beta) and J(gamma beta) were calculated, Peak areas of 2,3-diphosphog lycerate (DPG), P-i, and adenosine triphosphate (ATP) were determined and corrected for blood contamination, saturation, and differences in nuclear Overhauser enhancements (NOE). The maximum thickness of the in terventricular septum (IVSmax) was determined from tomographic long-ax is images and expressed as number of standard deviations above the mea n of the normal population (Z score). The patients were then divided i nto 2 groups: 6 patients with moderate HCM (HCMm, Z score less than or equal to 5) and 7 patients with severe HCM (HCMs, Z score > 5). No di fferences between both groups and a control group of healthy volunteer s (n = 16) were found with respect to phosphocreatine (PCr)/gamma-ATP ratio, pH(i), or the coupling constants. Only the PCr/P-i ratio differ ed significantly from the control group (HCMall, alpha < 0.05, HCMs, a lpha < 0.02, 2-sided U test). The decrease of the PCr/Pi ratio in pati ents with HCM is probably caused by ischemically decreased oxygen supp ly in the severely hypertrophied myocardium. (C) 1997 by Excerpta Medi ca, Inc.