Updates on epicardial adipose tissue mechanisms on atrial fibrillation

Abstract

Summary Obesity is a well‐known risk factor for atrial fibrillation (AF). Local epi‐myocardial or intra‐myocardial adiposity caused by aging, obesity, or cardiovascular disease (CVD) is considered to be a better predictor of the risk of AF than general adiposity. Some of the described mechanisms suggest that epicardial adipose tissue (EAT) participates in structural remodeling owing to its endocrine activity or its infiltration between cardiomyocytes. Epicardial fat also wraps up the ganglionated plexi that reach the myocardium. Although the increment of volume/thickness and activity of EAT might modify autonomic activity, autonomic system dysfunction might also change the endocrine activity of epicardial fat in a feedback response. As a result, new preventive therapeutic strategies are focused on reducing adiposity and weight loss before AF ablation or inhibiting autonomic neurotransmitter secretion on fat pads during open‐heart surgery to reduce the recurrence or postoperative risk of AF. In this manuscript, we review some of the novel findings regarding the pathophysiology and associated risk factors of AF, with special emphasis on the role of EAT in the electrical, structural, and molecular mechanisms of AF initiation and maintenance. In addition, we have included a brief note provided on epicardial fat preclinical models that could be useful for identifying new therapeutic targets.

Sex Differences in Epicardial Adipose Tissue: Association With Atrial Fibrillation Ablation Outcomes

“…Reasons for the differences may comprise sex-specific atrial electrophysiologic properties, atrial remodeling, and mechanisms of atrial fibrosis ( 23 ). Obesity-related AF has been gradually increased, and obesity has been considered a crucial and modifiable risk factor for AF development ( 11 , 24 , 25 ). However, obesity can be an attribute of general adiposity with variable degrees of cardiovascular and metabolic presentations.…”

“…Over the past few years, epicardial adipose tissue (EAT) has aroused increasing attention as it has been reported to play a role in the development and maintenance of AF and has a stronger relationship to AF presence and severity compared with other adiposity markers [e.g., waist circumference, waist/hip ratio, and body mass index (BMI)] ( 11 – 13 ). EAT, as the metabolically active visceral adipose depot closest to the myocardium, exhibits cell-to-cell contact or infiltration and shares the same blood supply as the myocardium, thus contributing to crosstalk with cardiomyocytes through direct paracrine and vasocrine pathways ( 11 , 14 ).…”

“…Over the past few years, epicardial adipose tissue (EAT) has aroused increasing attention as it has been reported to play a role in the development and maintenance of AF and has a stronger relationship to AF presence and severity compared with other adiposity markers [e.g., waist circumference, waist/hip ratio, and body mass index (BMI)] ( 11 – 13 ). EAT, as the metabolically active visceral adipose depot closest to the myocardium, exhibits cell-to-cell contact or infiltration and shares the same blood supply as the myocardium, thus contributing to crosstalk with cardiomyocytes through direct paracrine and vasocrine pathways ( 11 , 14 ). Some existing studies have suggested that when compared with total EAT, left atrial EAT is more significantly correlated with markers of atrial fibrillation (e.g., atrial structural remodeling and vulnerability), likely because the secretion of pro-inflammatory and anti-inflammatory adipokines by EAT around the left atrium could directly affect the left atrial wall and interact with cardiac autonomic nervous system ( 15 – 17 ).…”

Evaluation of Patients with Angiographically-Confirmed Coronary Artery Disease to Investigate the Association Between Epicardial Fat Thickness and Atrial Fibrillation

“…They suggested that BUN and Cr levels were predictors of postoperative atrial fibrillation after off-pump cardiopulmonary bypass grafting surgery. However, they did not investigate the relationship between LA diameter and BUN and Cr levels [ 44 ]. Moreover, in the present study, Pearson correlation coefficient analysis indicated that BNP, Cr, and BUN were all positively correlated with each other and positively correlated with LA diameter, but were negatively correlated with LVEF.…”

Left Ventricular Summit—Concept, Anatomical Structure and Clinical Significance

“…This distance might impact ventricular potential amplitude recorded from the great cardiac vein if the epicardial adipose tissue is sufficiently thick. Moreover, the thick adipose tissue layer may have a pro-arrhythmogenic activity and negatively influence the success rate of electrophysiological procedures performed within the LVS [40][41][42].…”