title: P-wave signal-averaged electrocardiogram for predicting atrial arrhythmia after cardiac surgery.
abstract: BACKGROUND
  Atrial arrhythmias (AF) are usually benign, but occur frequently after cardiac surgery. P-wave signal-averaged electrocardiogram has been used to characterize atrial conduction delay as a marker of risk of AF during sinus rhythm.
  
  
  METHODS
  Ninety-five patients undergoing either primary isolated coronary artery bypass grafting or aortic valve replacement were enrolled. The duration and the root mean square voltage for the last 20 ms of filtered (40 to 300 Hz) P-wave of the spatial magnitude were recorded before surgery. Any episode of postoperative atrial fibrillation, atrial flutter, or paroxysmal atrial fibrillation lasting longer than 1 hour was considered as AF.
  
  
  RESULTS
  Twenty-eight patients (29%) exhibited AF 3.0 +/- 2.3 days after surgery. The P-wave duration recorded with P-wave signal-averaged electrocardiogram was significantly prolonged in patients with AF (135 +/- 14 ms versus 127 +/- 9 ms; p = 0.002). Patients with AF more often had dilated left atrium (p = 0.003), left ventricular hypertrophy (p = 0.03), and advanced age (p = 0.02). Logistic regression analysis identified the following three variables as predictive of AF: P-wave duration of 135 ms or greater (p = 0.02; odds ratio, 3.5), patients 70 years of age and older (p = 0.03; odds ratio, 3.2), and left atrial dimension of 35 mm or greater (p = 0.03; odds ratio, 3.2). If a patient had two or more of these three risk factors, the occurrence of AF was predicted with a sensitivity of 75%, specificity of 76%, positive predictive accuracy of 57%, and negative predictive accuracy of 88%.
  
  
  CONCLUSIONS
  The prolonged P-wave duration recorded with P-wave signal-averaged electrocardiogram, together with advanced age and left atrial enlargement, is a potent and independent predictor of AF after cardiac surgery. Patients with these risk factors may benefit from prophylactic antiarrhythmic treatment.
authors.affiliation: Department of Surgery, Kurume University, Kurume, Japan. nobuhiko@med.kurume-u.ac.jp
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hayashida
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shojima
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yokokura
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Hori
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yoshikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tomoeda
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Aoyagi
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000601:surgery; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000209:etiology*; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004562:Electrocardiography; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012680:Sensitivity and Specificity