Epicardial fat can mimic pericardial effusion on transoesophageal echocardiogram

A 71-year-old woman with paroxysmal atrial fibrillation underwent transoesophageal echocardiography for evaluation of thrombus prior to atrial fibrillation ablation therapy. Transoesophageal echocardiographic images showed no thrombus but demonstrated an echo-free space adjacent to the right ventricle suggestive of a small pericardial effusion (Figure 1A; see Supplementary data online, Movie S1). Real-time three-dimensional transoesophageal echocardiographic images of the right ventricle were also suggestive of pericardial effusion (Figure 1B; see Supplementary data online, Movie S2). However, when the image gains were increased, the echo-free space showed increased texture (Figure 1C; see Supplementary data online, Movie S3) more consistent with epicardial fat than with pericardial effusion. Additional transthoracic echocardiographic images and a retrospective review of the patient's chest computed tomogram with contrast confirmed the presence of epicardial fat. No pericardial effusion was observed on the chest computed tomogram. Specifically, the chest computed tomogram showed attenuation values of −116 HU in the area adjacent to the right ventricle (Figure 1D), which was compatible with epicardial fat rather than pericardial effusion.