title: Association of high intracellular, but not serum, heat shock protein 70 with postoperative atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation is a common arrhythmia, after cardiac surgery. Reperfusion injury and inflammation associated with cardiac surgery are thought to be involved in its pathogenesis. We hypothesized that cytoprotective effects associated with heat shock protein 70 (HSP70) could counteract these proarrhythmic insults. We therefore set out to examine the influence of heat shock protein 70 on the incidence of postoperative atrial fibrillation.
  
  
  METHODS
  We prospectively recruited 80 patients undergoing elective coronary artery bypass surgery. Blood samples were collected preoperatively. Right atrial tissue was obtained at surgery. Incidence of postoperative atrial fibrillation and its duration were noted. Using a nested case-control design, 15 patients who developed atrial fibrillation were matched for operative procedure, age, sex, and beta-blocker usage, with 15 controls from the remaining patients. Atrial heat shock protein 70 was subsequently quantified by immunohistochemistry. Serum heat shock protein was measured using enzyme-linked immunosorbent assay and high sensitivity C-reactive protein was determined by immunoturbidometric assay.
  
  
  RESULTS
  Intracellular HSP70 level was significantly higher in patients who did not develop atrial fibrillation (35 +/- 13 vs 19 +/- 15; p = 0.006). Atrial HSP70 level negatively correlated with atrial fibrillation; independent of other risk factors (odds ratio = 0.90; 95% confidence interval 0.84 to 0.99, p = 0.02). Serum HSP70 levels were similar in both groups (p = 0.81) and did not correlate with intracellular levels (p = 0.38). Preoperative C-reactive protein levels were similar in both groups (p = 0.93).
  
  
  CONCLUSIONS
  Intracellular, but not serum, HSP70 level is negatively correlated with postoperative atrial fibrillation. This suggests a cardioprotective and an antiarrhythmic role for intracellular HSP70.
authors.affiliation: Department of Cardiothoracic Surgery, St. George's Hospital and Medical School, London, United Kingdom.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Mandal
authors.forename: Evelyn
authors.initials: E
authors.lastname: Torsney
authors.forename: Jan
authors.initials: J
authors.lastname: Poloniecki
authors.forename: A John
authors.initials: AJ
authors.lastname: Camm
authors.forename: Qingbo
authors.initials: Q
authors.lastname: Xu
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahangiri
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000209:etiology* / Q000378:metabolism; D016022:Case-Control Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis* / Q000097:blood; D006325:Heart Atria / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D008297:Male; D011446:Prospective Studies
chemical_list: D018840:HSP70 Heat-Shock Proteins