title: Severe Cardiac Autonomic Derangement and Altered Ventricular Repolarization Pave the Way to Postoperative Atrial Fibrillation.
abstract: OBJECTIVE
  Postoperative atrial fibrillation (POAF) is a frequent complication after heart surgery. It has been shown that cardiac autonomic derangement plays a significant role in the genesis of atrial fibrillation (AF) and that AF might also be promoted by altered repolarization. Thus, the aim of our study was to determine the levels of cardiac autonomic modulation and repolarization properties in patients developing POAF.
  
  
  METHODS
  Seventy-nine patients scheduled for aortic and/or coronary artery bypass grafting surgery with cardiopulmonary bypass were enrolled prospectively. High-resolution 20-minute electrocardiogram recordings were obtained day before surgery to determine P, PR, QT, and QTc intervals, as well as linear (time and frequency domain) and nonlinear heart rate variability parameters (fractal dimension and detrended fluctuation analysis). QTc interval was calculated using Framingham correction.
  
  
  RESULTS
  Twenty-nine patients developed POAF (AF group), and 50 did not (non-AF group). Groups were similar regarding demographics, surgery type, and perioperative characteristics, except for older age in the AF group. QT and QTc intervals (Framingham) were longer in the AF group [442 (44) vs 422 (28) milliseconds, P = 0.018; and 448 (44) vs 431 (24) milliseconds, P = 0.031 and P = 0.019, respectively]. Time domain heart rate variability parameter PNN50 (percentage of pairs of adjacent NN intervals differing >50 milliseconds) was higher [14% (21%) vs 8% (16%), P = 0.015], and nonlinear parameter detrended fluctuation analysis α2 was lower in the AF group [0.81 (0.21) vs 0.91 (0.20), P = 0.031].
  
  
  CONCLUSIONS
  Profound cardiac autonomic derangement, suggestive of parasympathetic excessive modulation, exists preoperatively in patients inclined to POAF after cardiac surgery, whereby parameters PNN50 and α2 differentiated the AF from the non-AF group. Prolonged QTc intervals are associated with an increased risk of POAF.
authors.affiliation: From the *Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia; †Department of Cardiac Surgery, Cardiovascular Center, Klinikum Nuernberg, Paracelsus Medical University, Nuremberg, Germany; ‡Department of Anesthesiology and Intensive Care, University Medical Center, Ljubljana, Slovenia; §Department of Communications and Computer Networks, Jožef Stefan Institute, Ljubljana, Slovenia; and ∥Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Jurij Matija
authors.initials: JM
authors.lastname: Kališnik
authors.forename: Eva
authors.initials: E
authors.lastname: Hrovat
authors.forename: Alenka
authors.initials: A
authors.lastname: Hrastovec
authors.forename: Viktor
authors.initials: V
authors.lastname: Avbelj
authors.forename: Janez
authors.initials: J
authors.lastname: Žibert
authors.forename: Borut
authors.initials: B
authors.lastname: Geršak
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000209:etiology / Q000503:physiopathology*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000503:physiopathology; D011184:Postoperative Period; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D000319:Adrenergic beta-Antagonists