title: Preservation of the anterior fat pad paradoxically decreases the incidence of postoperative atrial fibrillation in humans.
abstract: OBJECTIVE
  The goal of this study was to determine if parasympathetic nerves in the anterior fat pad (FP) can be stimulated at the time of coronary artery bypass surgery (CABG), and if dissection of this FP decreases the incidence of postoperative atrial fibrillation (AF).
  
  
  BACKGROUND
  The human anterior epicardial FP contains parasympathetic ganglia and is often dissected during CABG. Changes in parasympathetic tone influence the incidence of AF.
  
  
  METHODS
  Fifty-five patients undergoing CABG were randomized to anterior FP preservation (group A) or dissection (group B). Nerve stimulation was applied to the FP before and after surgery. Sinus cycle length (CL) was measured during stimulation. The incidence of postoperative AF was recorded.
  
  
  RESULTS
  Of the 55 patients enrolled, 26 patients were randomized to group A, and 29 patients were randomized to group B. In all of the 55 patients, the FP was identified before initiating cardiopulmonary bypass by CL prolongation with stimulation (865.5 +/- 147.9 ms vs. 957.9 +/- 155.1 ms, baseline vs. stimulation, p < 0.001). In group A, stimulation at the conclusion of surgery increased sinus CL (801.8 +/- 166.4 ms vs. 890.9 +/- 178.2 ms, baseline vs. stimulation, p < 0.001). In group B, repeat stimulation failed to increase sinus CL (853.6 +/- 201.6 ms vs. 841.4 +/- 198.4 ms, baseline vs. stimulation, p = NS). The incidence of postoperative AF in group A (7%) was significantly less than that in group B (37%) (p < 0.01).
  
  
  CONCLUSIONS
  This is the first study demonstrating that direct stimulation of the human anterior epicardial FP slows sinus CL. This parasympathetic effect is eliminated with FP dissection. Preservation of the human anterior epicardial FP during CABG decreases incidence of postoperative AF.
authors.affiliation: Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, 2500 MetroHealth Drive, Cleveland, OH 44109, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Cummings
authors.forename: Inderjit
authors.initials: I
authors.lastname: Gill
authors.forename: Rami
authors.initials: R
authors.lastname: Akhrass
authors.forename: MarkAlain
authors.initials: M
authors.lastname: Dery
authors.forename: Lee A
authors.initials: LA
authors.lastname: Biblo
authors.forename: Kara J
authors.initials: KJ
authors.lastname: Quan
mesh_terms: D000273:Adipose Tissue / Q000294:innervation* / Q000502:physiology*; D001281:Atrial Fibrillation / Q000209:etiology / Q000517:prevention & control*; D001283:Atrioventricular Node / Q000294:innervation* / Q000502:physiology*; D001026:Coronary Artery Bypass / Q000379:methods*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017764:Parasympathectomy / Q000379:methods; D011183:Postoperative Complications / Q000517:prevention & control; D016896:Treatment Outcome