P-31 NMR-SPECTROSCOPY DETECTS METABOLIC ABNORMALITIES IN ASYMPTOMATICPATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

Background-Hypertrophic cardiomyopathy (HCM) often causes sudden, unex pected death in adolescents and young adults. Alterations in myocardia l metabolism are considered to be causes for contractile dysfunction. We examined the question of whether metabolic abnormalities antedate t he manifestation of symptoms in patients with HCM. Methods and Results -Proton-decoupled P-31 NMR spectroscopy of the anterior left ventricul ar wall of the heart of 14 young, asymptomatic patients with HCM was p erformed with a 1.5-T whole-body imager. Spectra of the phosphate meta bolites were compared with those of normal control subjects. The patie nts exhibited a significantly reduced (P<0.02) ratio of phosphocreatin e (PCr) to ATP of 1.98 +/- 0.37 (mean +/- SD), compared with 2.46 +/- 0.53 obtained in 11 normal control subjects. In addition, the group of patients with severe hypertrophy of the interventricular septum (n=8) showed a significantly increased (P<0.05) P-i-to-PCr ratio, with a P- i x 100/PCr of 20.0 +/- 8.3 versus 9.7 +/- 7.2 in control subjects. Bo th abnormalities are similar to those found in ischemic myocardium. Th is view is also supported by a significantly increased (P<0.01) phosph omonoester (PME)-to-PCr ratio, with a PME x 100/PCr of 20.7 +/- 11.2 c ompared with 8,4 +/- 6.7 in control subjects, indicating altered gluco se metabolism. Conclusions-P-31 NMR spectroscopy detects alterations o f myocardial metabolism in asymptomatic patients with HCM. These alter ations may contribute to the understanding of the pathophysiology and natural history of the disease.