title: Correlation of QT dispersion with indices used to evaluate the severity of familial ventricular arrhythmias in Boxers.
abstract: OBJECTIVE
  To measure QT interval duration and QT dispersion in Boxers and to determine whether QT variables correlate with indices of disease severity in Boxers with familial ventricular arrhythmias, including the number of ventricular premature complexes per day, arrhythmia grade, and fractional shortening.
  
  
  METHODS
  25 Boxers were evaluated by ECG and echocardiography.
  
  
  METHODS
  The QT interval duration was measured from 12-lead ECG and corrected for heart rate (QTc), using Fridericia's formula. The QT and QTc were calculated for each lead, from which QT and QTc dispersion were determined. Echocardiography and 24-hour ambulatory ECG were performed to evaluate for familial ventricular arrhythmias. Total number of ventricular premature complexes, arrhythmia grade, and fractional shortening were determined and used as indices of disease severity.
  
  
  RESULTS
  There was no correlation between any QT variable and total number of ventricular premature complexes, arrhythmia grade, or fractional shortening. No difference between QT dispersion and QTc dispersion was identified, and correction for heart rate did not affect the results.
  
  
  CONCLUSIONS
  QT interval duration and dispersion did not correlate with indices of disease severity for familial ventricular arrhythmias. Heart rate correction of the QT interval did not appear to be necessary for QT dispersion calculation in this group of dogs. QT dispersion does not appear to be a useful noninvasive diagnostic tool in the evaluation of familial ventricular arrhythmias of Boxers. Identification of affected individuals at risk for sudden death remains a challenge in the management of this disease.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus 43210, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Spier
authors.forename: K M
authors.initials: KM
authors.lastname: Meurs
authors.forename: W W
authors.initials: WW
authors.lastname: Muir
authors.forename: L B
authors.initials: LB
authors.lastname: Lehmkuhl
authors.forename: R L
authors.initials: RL
authors.lastname: Hamlin
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000662:veterinary*; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D004562:Electrocardiography / Q000379:methods / Q000662:veterinary*; D015716:Electrocardiography, Ambulatory / Q000662:veterinary; D005260:Female; D006339:Heart Rate; D008297:Male; D018754:Ventricular Dysfunction / Q000175:diagnosis / Q000662:veterinary*