DOINA BUTCOVAN, TEODOR OBOROCEANU, CIPRIAN CIMPEANU, AUREL MIRONESCU, RALUCA ECATERINA HALIGA, ALIN CONSTANTIN PINZARIU, RAOUL VASILE LUPUSORU, EUGENIA POPESCU, VERONICA MOCANU THE INVOLVEMENT OF EPICARDIAL ADIPOSITY AND INFLAMMATION IN POSTOPERATORY ATRIAL FIBRILATION - IMMUNOHISTOCHEMICAL QUALITATIVE AND QUANTITATIVE ASSESSMENT Postoperatory atrial fibrillation (AF) is a common complication after cardiac surgery. Among others cardiac structural changes, epicardial adiposity (EA) and inflammation could be associated with increased cardiovascular risk, including AF. Because there are not enough studies on the association between epicardial fat and inflammation in AF, this paper assesses the association between structural changes in human right atrial appendages (RAA) in patients with and without AF with focus on EA and inflammation. RAA specimens from 20 coronary patients (ages 60 ± 10 years) were divided in 2 groups including patients with and without postoperatory AF. Histological, immunohistochemical (IMH) and morphometrical methods were used for assessing EA, myocardial fatty infiltration, epicardial inflammatory foci, cardiomyocytes size and vacuolation and extent of interstitial fibrosis. Atrial changes were found in most patients from both groups, having higher proportions in postoperatory AF patients. EA extent and myocardial fatty infiltration were twofold to threefold higher in patients with postoperatory AF and associated epicardial mononuclear inflammation. RAA structural changes can indicate the susceptibility to develop postoperatory AF. Currently, EA and inflammation have recently emerged as new independent AF risk factors. So, we proposed to study RAA structural changes, including EA, epicardial inflammatory foci in relation with postoperatory AF frequency.