The Atrial appendages are remnants of the original embryonic atrium formed during the third week of gestation.(1)Both the right and left appendages are trabeculated, with muscle bars largely running parallel to each other giving a comb-like appearance (hence termed pectinate muscles), but these are less pronounced on the left.(2) Left atrial appendage locatedon the lateral wall of heart close to the left circumflex artery, which is relevant for surgical occlusion.(2)Right atrial appendage is broad and triangular with a wide junction. (3) Atrial fibrillation (AF) itself and underlying heart diseases lead to changes in atrial function and structure. Often it is difficult to distinguish the contribution of AF to these multiple processes known as atrial remodeling.(4,5)Molecular research of structurally changed human atria has been preferably focused on various ion channels (6,7)and proteins involved in calcium homeostasis,(8,9) while the links between different pathways involved in the pathology of AF have so far not been investigated.(10)This has stimulated the search for novel approaches that could help to find the relationship between the underlying conditions.Nuclear receptors (NRs) are master regulators of a plethora of cellular and biological processes such as cell proliferation, migration, apoptosis, metabolism, and differentiation. Recently, NRs of the NR4A subfamily have emerged as key players in the pathophysiology of heart diseases