Epicardial fat measurements with both MRI and echocardiography in HFrEF and HFpEF
Epicardial fat in heart failure with reduced versus preserved ejection fraction
Introduction and methods
Epicardial adipose tissue (EAT) plays an important role in the regulation of myocardial function and may contribute to the maintenance of cardiac health via mechanical, metabolic, thermogenic, and paracrine functions. On the other hand, inflammation of EAT in obesity may lead to myocardial dysfunction in HF . However, data from multiple studies in the past have shown conflicting associations between EAT and HF [2-6]. Measuring EAT with either MRI or echocardiography may impact results and none of the previous studies used both methods for the measurement of EAT. MRI allows for whole heart EAT volume and mass measurements, while echocardiography only allows for measurements of EAT thickness over the free wall of the right ventricle.
This prospective, multicentered study compared EAT mass by MRI (EAT-MRI) and EAT thickness by echocardiography (EAT-echo) in patients with HFpEF (n=47) and HFrEF (n=204) and controls without HF (n=113). All individuals underwent cardiac MRI and echocardiography.
Cardiac volume, left ventricular mass (LVM), and global longitudinal strain (GLS) were determined by standard MRI methods. Myocardial T1 mapping of basal and mid short-axis slices were used to estimate extracellular volume (ECV). EAT-echo thickness was defined as the echo-free space between myocardium and pericardium layers in the parasternal long or short-axis view on two-dimensional transthoracic echocardiography.
- EAT-MRI mass was largest in in patients with HFrEF compared with those without HF (P<0.001), after adjustment for confounders. EAT-MRI mass was similar between patients with HFpEF and controls .
- In contrast, EAT-echo thickness was lowest in in patients with HFrEF compared tocontrols without HF (P<0.03). There was no significant difference in EAT-echo thickness between patients with HFpEF and controls.
- A larger heart would be expected to have a higher overall EAT-MRI mass. EAT-MRI mass was therefore corrected for LVM. the resulting EAT-MRI/LVM ratio was lower in HFrEF and HFpEF compared to controls (P<0.001 and P=0.0081, respectively).
- Greater EAT-MRI mass was associated with worse left ventricular GLS (β=-0.21, P<0.001) in patients with HF. The strongest association was found in patients with HFpEF (β=-0.48, P=0.003) compared to patients with HFrEF (β=-0.15, P=0.016).
- Larger EAT-MRI mass was only associated with higher cardiac ECV in HFpEF (β=-0.63, P=0.034), not in patients with HFrEF (Pinteraction<0.001).
This study showed that EAT-MRI mass was higher in patients with HFrEF compared to controls. However, EAT-MRI/LVM-MRI ratio was lower in HFrEF and HFpEF compared to controls without HF, and EAT-echo thickness was lower in patients with HFrEF compared to controls. Larger EAT-MRI mass was stronger associated with left ventricular dysfunction (increased GLS) and myocardial fibrosis (larger ECV) in patients with HFpEF than in those with HFrEF.