The role of visceral fat is undeniable when it comes to cardiovascular diseases. Fatty tissue of the heart, also known as epicardial adipose tissue (EAT), is suspected to play an important role in patients with heart failure and could be a useful clinical marker. However, estimating the quantity of adipose tissue that lies adjacent to this vital organ is a very challenging task.
Currently, the gold-standard method to estimate the volume of EAT is cardiac magnetic resonance (CMR) imaging. CMR is a safe, non-invasive method to study the function and morphology of the heart. Despite these advantages, CMR is not available in the vast majority of medical centres, and it continues to be an expensive diagnostic and prognostic tool. On the other hand, there is transthoracic echocardiography, a safe, non-invasive, widely available and cheap imaging method, on which EAT can be measured as thickness.
In a recent publication, UMCG researchers Gijs van Woerden, Dirk J. van Veldhuisen and colleagues have compared EAT measurements of 117 patients with heart failure. CMR and echocardiography images from all patients were analysed by a senior and a junior observer.
(A) Typical example of epicardial adipose tissue (EAT) on cardiac magnetic resonance (CMR) imaging on long-axis 4 chamber-view and (B)short-axis view. (C) Typical example of echocardiographic EAT thickness on parasternal long-axis view and (D) short-axis view. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. To the right, schematic images of the heart (creater with BioRender) for anatomical reference.
They found a modest correlation between the volume (measured with CMR) and thickness (measured with echocardiography) of EAT. This is most likely because CMR provides a three-dimensional estimation, while echocardiography offers only two dimensions, and therefore shows less accuracy. Furthermore, echocardiography is a technique that relies greatly on the manual ability and expertise of the health professional conducting it. Thus, it is not a surprise that they also found a limited degree of agreement between the junior and senior observations.
They conclude that echocardiographic measurement of EAT is limited and, taking cost-effectiveness into account, CMR is preferred. However, the association was still significant, and it could be helpful in large cohorts when investigating cardiovascular pathologies.
‘The value of echocardiography in the assessment of epicardial adipose tissue is limited and should therefore be used with caution’ Gijs van Woerden.