Impaired left ventricular energy metabolism in patients with hypertrophic cardiomyopathy is related to the extension of fibrosis at gadolinium delayed enhanced MR imaging

OBJECTIVE: Areas of intramyocardial late enhancement (LE) at delayed enhanced magnetic resonance imaging (DE-MRI) and reduction of myocardial phosphocreatine (PCr)/ATP-ratio at phosphorous MR spectroscopy ((3)(1)P-MRS), are both reported in hypertrophic cardiomyopathy (HCM) and indicate areas of increased interstitial myocardial space with fibrosis and impairment of myocardial energy metabolism, respectively. We sought to ascertain whether in HCM patients the abnormal features of left ventricular (LV) interstitial space revealed by DE-MRI correlated with impaired LV energy metabolism shown at (3)(1)P-MRS. Design and PATIENTS: 19 patients with HCM proved by histological analysis of multiple endomyocardial biopsies and with normal coronary arteries, underwent cardiac Magnetic Resonance imaging including DE-MRI and (3)(1)P-MRS. DE-MRI for detection and quantification of Late Enahncement (LE) and (3)(1)P-MRS to assess the myocardial PCr/ATP-ratio were performed by means of a 1.5T magnet. 19 healthy subjects matched for gender and age were studied by (3)(1)P-MRS, as control group. RESULTS: LE areas in the LV wall were found in 17 out of 19 patients with an extension ranging from 0.8 to 19.5% of the LV-mass (mean value: 7.6 +/- 5.6%). The PCr/ATP-ratio was lower in HCM patients when compared to control subjects (2.18 +/- 0.41 vs 2.41 +/- 0.30; P<0.05). LE% and PCr/ATP-ratio were inversely related (R=-0.57; P<0.05) and LE% was the stronger predictor of PCr/ATP-ratio by multivariate analysis. CONCLUSIONS: This study demonstrated that the known alteration of PCr/ATP-ratio observed in HCM patients is correlated with the presence of fibrotic areas in the myocardium of left ventricle.