Association of epicardial adipose tissue and left atrial size on non-contrast CT with atrial fibrillation: The Heinz Nixdorf Recall Study

Important article by Mahabadi et al (1) reported total epicardial adipose tissue (EAT) volume measured in non-contrast CT with the prevalence of atrial fibrillation (AF). In this population-based cohort study EAT volume was~1.5-fold higher in subjects with AF at a baseline. Not surprisingly, stronger relationship was detected between left atrium size and AF prevalence. None of the traditional risk factors, such as age, gender, body mass index (BMI), and systolic blood pressure significantly diminished these correlations. Also stronger correlation of EAT with AF was found in women than in men. The authors postulated that the association between EAT and AF may be explained by the strong link of EAT with LA size, which itself is well established predictor of AF. On top of that the authors suggested that their results did not supported the hypothesis of long-term effect of EAT in the development of AF. We believe that paracrinally influence of EAT plays an important role in the development of coronary atherosclerosis, as well as on the prevalence of AF. We have previously published number of articles considering inflammatory cytokines released from EAT in the setting of coronary artery disease (2, 3). Recently we have also focused on inflammatory influence of EAT on the occurrence of AF (4). Local EAT inflammatory activity measured using FDG- PET/CT was higher in patients with the history of AF than in non-AF controls. Inflammatory activity of EAT adjacent to left atrium, atrioventricular groove, and left main artery was greater than in subcutaneous or visceral thoracic fat. In multivariate logistic regression analysis SUV near the roof of left atrium (odds ratio 116.80, 95% confidence interval 5.70 to 2394.14, p=0.002) was significant predictor of AF. In our opinion inflammatory pathways may influence the structural changes within the left atrium and represent a novel mechanism underlying the prevalence of AF. One of the proposed mechanisms linking EAT and AF might be the autonomic ganglionated plexi present in EAT taking part in the initiation and continuation of AF (5). Girerd et al. postulated that locally measured periatrial EAT rather than total EAT volume triggered substantial endothelial dysfunction within the LA and leads to the higher occurrence of AF (6). There was no association between measured biomarkers and total EAT, as well as BMI. This may partly explain the lack of association between total EAT volume and AF in follow up examination in The Heinz Nixdorf Recall Study. Also in a recent article by Iacobellis et al. EAT thickness measured locally over the right ventricle correlated with chronic AF, as compared to paroxysmal AF (7). Summarizing, we would like to postulate that local influence and inflammatory/paracrine activity of EAT rather than total EAT volume may affect the appearance of AF.

1. Mahabadi A, Lehmann N, K?lsch H, Bauer M, Dykun I, Kara K, Moebus S, J?ckel K-H, Erbel R, M?hlenkamp S. Association of epicardial adipose tissue and left atrial size on non-contrast CT with atrial fibrillation: The Heinz Nixdorf Recall Study. Eur Heart J Cardiovasc Imaging 2014 15:863 -869; doi:10.1093/ehjci/jeu006. 2. Mazurek T, Zhang L, Zalewski A, Mannion JD, Diehl JT, Arafat H, Sarov- Blat L, O'Brien S, Keiper EA, Johnson AG, Martin J, Goldstein BJ, Shi Y. Human epicardial adipose tissue is a source of inflammatory mediators. Circulation 2003;108:2460-2466. 3. Mazurek T. Proinflammatory capacity of adipose tissue - new insights in the pathophysiology of atherosclerosis. Polish Heart Journal. 2009;67:1119 -1124. 4. Mazurek T, Kiliszek M, Kobylecka M, Kochman J, Filipiak K, Kr?licki L, Skubisz-G?uchowska J, Opolski G. Proinflammatory activity of epicardial adipose tissue may affect the occurrence of atrial fibrillation. Am J Cardiol 2013;DOI:10.1016/j.amjcard.2014.02.005. 5. Karasoy D, Bo Jensen T, Hansen ML, Schmiegelow M, Lamberts M, Gislason GH, et al. Obesity is a risk factor for atrial fibrillation among fertile young women: a nationwide cohort study. Europace 2013; 15: 781-6. 6. Girerd N, Scridon A, Bessiere F, Chauveau S, Geloen A, Morel E, Chevalier P. Periatrial epicardial fat is associated with markers of endothelial dysfunction in patients with atrial fibrillation. PLoS ONE 8(10): e77167. doi:10.1371/journal.pone.0077167. 7. Iacobellis G, Zaki MC, Garcia D, Willens HJ. Epicardial fat in atrial fibrillation and heart failure. Horm Metab Res 2014; 46: 1-4.

Conflict of Interest:

None declared