Cardiac Adiposity and Arrhythmias: The Role of Imaging

Abstract

Increased cardiac fat depots are metabolically active tissues that have a pronounced pro-inflammatory nature. Increasing evidence supports a potential role of cardiac adiposity as a determinant of the substrate of atrial fibrillation and ventricular arrhythmias. The underlying mechanism appears to be multifactorial with local inflammation, fibrosis, adipocyte infiltration, electrical remodeling, autonomic nervous system modulation, oxidative stress and gene expression playing interrelating roles. Current imaging modalities, such as echocardiography, computed tomography and cardiac magnetic resonance, have provided valuable insight into the relationship between cardiac adiposity and arrhythmogenesis, in order to better understand the pathophysiology and improve risk prediction of the patients, over the presence of obesity and traditional risk factors. However, at present, given the insufficient data for the additive value of imaging biomarkers on commonly used risk algorithms, the use of different screening modalities currently is indicated for personalized risk stratification and prognostication in this setting.

Keywords: adipose tissue; arrhythmogenesis; atrial fibrillation; cardiac fat; cardiac magnetic resonance; echocardiography.

Figure 1

Transthoracic echocardiographic view showing EAT and PAT as echo-lucent areas in front of the RV free wall. EAT is pointed by a white arrow and PAT by a red arrow. Ao: aorta; EAT: epicardial adipose tissue; LA: left atrium; LV: left ventricle; PAT: pericardial tissue; RV: right ventricle.

Figure 2

Cardiac Computed Tomography: EAT (depicted in blue) is located between the myocardium and visceral pericardium, PAT (depicted in green) is located adherent and external to the parietal pericardium. EAT: epicardial adipose tissue; PAT: pericardial tissue. de Wit-Verheggen VHW, et al. Cardiovasc Diabetol. 2020;19:129, under Creative Commons license 4.0.

Figure 3

CMR Dixon images. A: Fat only image. B: Fat only Image with the epicardial outlines (arrows). C: Segmented fat voxels with the transferred region of interest. CM: cardiac magnetic resonance. Kropidlowski C, et al. Int J Cardiol Heart Vasc. 2020;27:100477, under Creative Commons license 4.0.