1H- and 31P-myocardial magnetic resonance spectroscopy in non-obstructive hypertrophic cardiomyopathy patients and competitive athletes.

Abstract

The clinical differentiation between athlete's heart and mild forms of non-obstructive hypertrophic cardiomyopathy (HCM) is crucial. We hypothesized that differences do exist between the myocardial metabolism of patients with non-obstructive HCM and competitive athletes (CAs). Our aim was to evaluate myocardial metabolism with 31P-MRS and 1H-MRS in HCM patients and CAs. After Ethics Committee approval, 15 CAs and 7 HCM patients were prospectively enrolled. They underwent a 1.5-T cardiac MR including electrocardiographically triggered cine images, single-voxel 1H-MRS and multivoxel 31P-MRS. 1H-MRS was performed after imaging using standard coil with the patient in the supine position; thereafter, 31P-MRS was performed using a dedicated coil, in the prone position. Data were reported as median and interquartile range. Mann-Whitney U test was used. In CAs, left ventricular mass index was 72 (66-83)g/m2, septal thickness 10 (10-11)mm, end diastolic volume index 95 (85-102)ml/m2, end systolic volume index 30 (28-32)ml/m2 and ejection fraction 68% (65-69%); in HCM patients, 81 (76-111)g/m2 (P=0.052), 18 (15-21)mm (P=0.003), 73 (58-76)ml/m2 (P=0.029), 20 (16-34)ml/m2 (P=0.274) and 68% (55-73%) (P=1.000), respectively. At 1H-MRS, total lipids were 35 (0-183) arbitrary units (au) for CA and 763 (155-1994) au for HCM patients (P=0.046). At 31P-MRS, PCr/γATP was 5 (4-6) au for CA and 4 (2-5) au for HCM patients (P=0.230). Examination time was 20min for imaging only, 5min for 1H-MRS and 15min for 31P-MRS. We observed a significant increase of myocardial lipids, but a preserved PCr/γATP ratio in the metabolism of HCM patients compared with competitive CAs.