title: The signal-averaged electrocardiogram of atrial activation in patients with or without paroxysmal atrial fibrillation.
abstract: OBJECTIVE
  To analyze the parameters of the time domain P-wave signal-averaged electrocardiogram (P-SAECG) and compare them with the P-wave duration on the conventional electrocardiogram (P on ECG) as well as the left atrium diameter (LAD) and left ventricular ejection fraction (EF) obtained on the echocardiogram in order to evaluate patients with paroxysmal atrial fibrillation (PAF).
  
  
  METHODS
  One hundred and eighty-one patients were included in the study: 117 with confirmed PAF and 64 without PAF. The P-SAECG parameters used were: the filtered P-wave duration (FPD), the root mean square (RMS) voltages in the last 40, 30 and 20 ms of the filtered P-wave (RMS 40, RMS 30 and RMS 20), the root mean square voltage of the filtered P-wave potentials (RMS P), the integral of the potentials during the filtered P-wave (Integral P) and the filtered P-wave late potential durations below 3 microV (PL<3).
  
  
  RESULTS
  The parameters that presented significant statistical differences between the groups were: FPD, RMS 40, 30 and 20, PL<3, P on ECG and LAD. The ROC curve calculations demonstrated the best cut-off points and performance estimates for each parameter: sensitivity, specificity, area under the curve and p-value (p).
  
  
  CONCLUSIONS
  The time domain P-SAECG proved to be a superior method to identify patients with paroxysmal atrial fibrillation than the conventional electrocardiogram and echocardiogram.
authors.affiliation: Instituto do Coração do Hospital das Clínicas, FM, USP, São Paulo, SP, Brazil.
authors.forename: José Osvaldo
authors.initials: JO
authors.lastname: Moreira
authors.forename: Paulo Jorge
authors.initials: PJ
authors.lastname: Moffa
authors.forename: Augusto Hiroshi
authors.initials: AH
authors.lastname: Uchida
authors.forename: Nancy Maria Martins de Oliveira
authors.initials: NM
authors.lastname: Tobias
authors.forename: César José
authors.initials: CJ
authors.lastname: Grupi
authors.forename: Bráulio
authors.initials: B
authors.lastname: Luna Filho
authors.forename: Flávio
authors.initials: F
authors.lastname: Tarasoutchi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology; D016275:Atrial Function / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted