Abstract 11761: Diffuse Myocardial Fibrosis in Hypertrophic Cardiomyopathy Can be Detected by Cardiac MRI and Correlates with Left Ventricular Filling Pressure
Purpose:In patients with hypertrophic cardiomyopathy (HCM) the extent of diffuse myocardial fibrosis and its relationship to diastolic function has not been described. We used a contrast-enhanced cardiac magnetic resonance (CMR) T1 mapping technique to non-invasively determine the extent and location of diffuse myocardial fibrosis in patients with HCM. Furthermore, we evaluated the relationship between diffuse myocardial fibrosis and diastolic function.
Methods:We performed CMR on 44 subjects - 30 with asymmetric septal hypertrophy due to HCM (70% male, mean age 49±13 years) and 14 control patients. Chamber dimensions, wall thickness, systolic function and patterns of regional myocardial fibrosis were evaluated with cine imaging and late gadolinium enhancement (LGE). A prototype T1 mapping sequence was used (excluding areas of regional LGE) to determine the post-contrast myocardial T1 time as an index of diffuse myocardial fibrosis at the basal, mid and apical levels of the left ventricle (LV). Diastolic function (including septal, lateral and mean E/e') was assessed by transthoracic echocardiography.
Results:Regional myocardial fibrosis was observed in 87% of the HCM group. Global post-contrast myocardial T1 times were significantly shorter in patients with HCM compared to controls, consistent with the presence of diffuse myocardial fibrosis (494 ± 92 ms vs. 563 ± 52 ms, p<0.01). This difference was most pronounced at the basal level (436 ± 82 ms vs. 530 ± 87 ms, p<0.01). In HCM patients, the global LV T1 time correlated with mean E/e' (r=-0.47, p=0.01).
Conclusions:Patients with HCM have shorter myocardial T1 times, particularly at the basal level of the LV, consistent with the presence of diffuse myocardial fibrosis. The extent of diffuse fibrosis correlates with LV filling pressure, suggesting a mechanistic link between diffuse myocardial fibrosis and abnormal diastolic relaxation in HCM.
- © 2011 by American Heart Association, Inc.