title: Significance of signal averaged electrocardiography in patients with advanced heart failure and intraventricular conduction delay.
abstract: OBJECTIVE
  Signal averaged electrocardiography is a noninvasive method to evaluate the presence of the potentials that are generated by tissues, activated later than their usual timing in the cardiac cycle. The purpose of this study was to demonstrate the correlation of data obtained via signal averaged electrocardiography and left ventricular dyssynchrony.
  
  
  METHODS
  We included the patients with advanced systolic left ventricular dysfunction (ejection fraction </= 35%) and intraventricular conduction delay. All patients underwent surface 12-lead electrocardiography, signal averaged ECG, and tissue Doppler echocardiography.
  
  
  RESULTS
  The study included 72 patients with mean age of 56.45+/-13.59 years. Mean QRS duration was 0.14 +/- 0.02 sec; 63.9% of patients had left bundle branch block. Linear regression demonstrated significant correlations between filtered QRS duration and interventricular mechanical delay (P<0.000, Y= 0.41X-24.76), root mean square 40 and peak velocity difference (P: 0.001, Y=-0.39X+109.72), root mean square 40 and Ts-SD-12 (P:0.026, Y=-o.26X+40.08), low amplitude signals duration and peak velocity difference (P<0.000, Y=0.44X+67.3) and finally low amplitude signals duration and Ts-SD-12 (P:0.31, Y=0.26X+28.23) as well. Area under the curve in ROC of filtered QRS duration was significant for the detection of interventricular mechanical delay. Areas under the curves in ROC of low amplitude signal duration and root mean square 40 were significant for the detection of peak velocity difference.
  
  
  CONCLUSIONS
  Signal averaged electrocardiography can have a role in predicting the amount of ventricular dyssynchrony. The duration of low amplitude signals and root mean square 40 have significant linear relations to some indices of intraventricular dyssynchrony.
authors.affiliation: Department of Cardiology, Imam Khomeini Hospital, Jondishapour University of Medical Sciences, Ahwaz, Iran. alastip@gmail.com
authors.forename: Mohammad
authors.initials: M
authors.lastname: Alasti
authors.forename: Majid
authors.initials: M
authors.lastname: Haghjoo
authors.forename: Abolfath
authors.initials: A
authors.lastname: Alizadeh
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Nikoo
authors.forename: Hamid Reza
authors.initials: HR
authors.lastname: Bonakdar
authors.forename: Bita
authors.initials: B
authors.lastname: Omidvar
authors.forename: Ali
authors.initials: A
authors.lastname: Kharazi
authors.forename: Bahman
authors.initials: B
authors.lastname: Cheraghian
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