title: Protective effect of epicardial adiponectin on atrial fibrillation following cardiac surgery.
abstract: OBJECTIVE
  Inflammation has been implicated in the pathogenesis of postoperative atrial fibrillation (AF). Adipose tissue secretes both pro-inflammatory cytokines such as interleukin-6 (IL-6) and anti-inflammatory mediators such as adiponectin. We set out to examine the association of adiponectin and IL-6, both circulating and locally produced by the epicardial adipose tissue, with AF development after cardiac surgery.
  
  
  METHODS
  A total of 90 consecutive patients undergoing cardiac surgery were evaluated. Blood samples were collected before induction of anaesthesia. Epicardial fat was obtained upon commencement of cardiopulmonary bypass. IL-6 and adiponectin levels were determined in serum and supernatant of epicardial adipose tissue organ cultures with two-site enzyme-linked immunosorbent assay (ELISA). Heart rhythm was assessed with continuous tele-monitoring for 72 h postoperatively, and with 6-hourly clinical examinations and daily electrocardiograms (ECGs) thereafter.
  
  
  RESULTS
  A total of 36 patients developed postoperative AF (40%). Baseline-serum IL-6 and adiponectin were not associated with AF (p = 0.86 and 0.95, respectively). Epicardial adipose tissue IL-6 levels did not correlate with the development of the arrhythmia either (p = 0.37). However, epicardial adiponectin release was lower in patients who developed AF than in those who remained in sinus rhythm (76 (interquartile range (IQR) 35-98) vs 53 ((IQR) 35-69) ng h(-1)g(-1) of tissue cultured, p = 0.066). Following linear regression, the association of epicardial adiponectin with AF almost reached statistical significance (p = 0.066). Multivariate logistic regression analysis of identified risk factors for AF, with the inclusion of epicardial adiponectin as an independent variable, revealed increased age (odds ratio (OR) 1.09, 95% confidence interval (CI) 1.02-1.17, p = 0.013) and epicardial adiponectin levels (OR 0.98, 95% CI 0.97-1.00, p = 0.054) as independent predictors of postoperative AF.
  
  
  CONCLUSIONS
  Increased epicardial adiponectin is associated with maintenance of sinus rhythm following cardiac surgery. This reinforces the inflammatory hypothesis in the pathogenesis of postoperative AF and may represent a novel therapeutic target for its effective prevention.
authors.affiliation: Department of Cardiothoracic Surgery, St George's Hospital, Blackshaw Road, London SW17 0QT, UK.
authors.forename: Antonios
authors.initials: A
authors.lastname: Kourliouros
authors.forename: Kalypso
authors.initials: K
authors.lastname: Karastergiou
authors.forename: Justin
authors.initials: J
authors.lastname: Nowell
authors.forename: Philemon
authors.initials: P
authors.lastname: Gukop
authors.forename: Morteza
authors.initials: M
authors.lastname: Tavakkoli Hosseini
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Valencia
authors.forename: Vidya
authors.initials: V
authors.lastname: Mohamed Ali
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahangiri
mesh_terms: D052242:Adiponectin / Q000097:blood / Q000502:physiology*; D000273:Adipose Tissue / Q000378:metabolism; D000368:Aged; D001281:Atrial Fibrillation / Q000209:etiology* / Q000378:metabolism / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000378:metabolism*; D011379:Prognosis; D046509:Tissue Culture Techniques
chemical_list: D052242:Adiponectin; D015415:Biomarkers; D018836:Inflammation Mediators; D015850:Interleukin-6