http://www.revistadechimie.ro REV.CHIM.(Bucharest)♦68♦No. 4 ♦2017 886 The Involvement of Epicardial Adiposity and Inflammation in Postoperatory Atrial Fibrilation - Immunohistochemical Qualitative and Quantitative Assessment DOINA BUTCOVAN 1 , TEODOR OBOROCEANU 2 *, CIPRIAN CIMPEANU 3 , AUREL MIRONESCU 3 , RALUCA ECATERINA HALIGA 2 , ALIN CONSTANTIN PINZARIU 2 , RAOUL VASILE LUPUSORU 2 , EUGENIA POPESCU 1 , VERONICA MOCANU 2 1 Grigore T. Popa University of Medicine and Pharmacy, Faculty of Medicine, Department of Morpho-Functional Sciences I, 16 Universitatii Str., 700115, Iasi, Romania 2 Grigore T. Popa University of Medicine and Pharmacy, Faculty of Medicine, Department of Morpho-Functional Sciences II, 16 Universitatii Str., 700115, Iasi, Romania 3 Transilvania University of Brasov, Faculty of Medicine, Department of Medical and Surgical Sciences, 29 Eroilor Blvd., 500036, Brasov, Romania 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. Keywords: epicardial inflammation, epicardial adiposity, atrial fibrillation, atrial fibrosis, cardiac surgery Atrial fibrillation (AF) is the most frequent cardiac arrhythmia in clinical practice and is often associated to profound structural alterations of the atrial myocardium. The atrial substrate refers to the various structural changes of the atrial wall, which result in disorganization and loss of homogeneity of the atrial myocardium and formation of re-entry circuits [1]. Increased interstitial fibrosis (IF) has been observed having a role in the formation of local conduction blocks [2]. In addition to the IF, myocytes tend to enlarge due to replacement of their contractile apparatus by accumulation of glycogen or by compensatory hypertrophy [3]. A large research effort has been dedicated to identify new biomarkers and therapeutic targets for cardiac arrhythmia. Recently, a relationship between the thickness of epicardial adipose tissue (EAT) and the incidence and severity of AF has been reported [4]. Adipose tissue is a biologically active organ releasing adipokines. It is also a major source of cytokines. There is no distinct barrier between the EAT and the adjacent myocardium, supporting the possibility of crosstalk between the two tissues [5]. EAT accumulation is often associated with fatty infiltration from the epicardial layer, which advances deep into the myocardium. This may contribute to myocardium functional disorganization and formation of local arrhythmogenic substrate [6]. The infiltration of adipocytes into the atrial myocardium could also disorganize the depolarization wave front favoring micro re-entry circuits and local conduction block. * email: teodor.oboroceanu@yahoo.com The discovery of a relationship between the abundance of atrial fatty deposits, epicardial inflammation and the risk and severity of AF, could open new research perspectives on the biology of the arrhythmogenic substrate. Experimental part Materials and methods Approval to conduct the research was obtained from the institution’s Board. The study included 20 patients hospitalized for coronary surgery in 2012, 14 men and 6 women aged between 36 and 74 years. All patients gave their consent to participate in the study prior to cardiopulmonary bypass surgery. We also had the Ethics Committee approval. All patients were monitored daily until discharge with continuous electrocardiographic recording with standard 12-lead electrocardiography. Only AF episodes lasting longer than 15 min were considered. Patients were considered to have postoperatory atrial fibrillation (PAF) if interventional therapy (drugs or electrical cardioversion) was required to restore sinus rhythm. The twenty coronary patients, 10 patients with PAF and 10 with postoperatory sinus rhythm (PSR), were selected by clinical criteria: absence of transitory PAF, no concomitant hyperthyroidism, and no valvular diseases. Tissue samples from the right atrial appendages (RAA) of the PAF group of patients were compared with samples from patients who remained in PSR.