Usefulness of Delayed Enhancement Magnetic Resonance Imaging to Differentiate Dilated Phase of Hypertrophic Cardiomyopathy and Dilated Cardiomyopathy

Abstract Background The dilated phase of hypertrophic cardiomyopathy (HCM) has a poor prognosis. For correct recognition of such patients, we compared the findings in cardiac delayed enhancement (DE)-magnetic resonance imaging (MRI) between HCM and dilated cardiomyopathy (DCM) patients. Methods and Results Sixty-five patients (HCM 39, DCM 26) underwent gadolinium-DTPA–enhanced MRI. The HCM patients were divided into those with preserved (HCM-P, n = 30) and those with impaired systolic function (HCM-I, n = 9). DE-MRI demonstrated focal or diffuse DE at the left ventricular (LV) wall in 60% of HCM-P and 100% of HCM-I, but in only 12% of DCM. The DE distributed mainly septal to the anterior wall of LV, but the DE volume against whole LV muscle volume was much larger in HCM-I than in HCM-P and DCM (4.1 ± 6.1% in HCM-P, 14.6 ± 11.9% in HCM-I, and 0.8 ± 2.4% in DCM, means ± SD, P < .05). In HCM, there were weak but significant correlations between DE volume, and LV end-diastolic volume and LV end-systolic volume. In HCM-P, the percent of length shortening in the segments with DE was lower than that without DE. Conclusions The HCM patients had more DE than the DCM patients, and DE volume correlated to lower global and local LV function. DE-MRI may be useful to evaluate myocardial damage in HCM patients, and to differentiate the dilated phase of HCM from DCM.