title: Diagnostic performance of P wave duration in the identification of left atrial enlargement in dogs.
abstract: OBJECTIVE
  To determine sensitivity and specificity of P wave duration in the identification of left atrial enlargement in dogs.
  
  
  METHODS
  Electrocardiograms from normal dogs and dogs with various cardiovascular diseases were evaluated. Inclusion criteria were the availability of an electrocardiogram showing a stable isoelectric line, easily recognizable P waves and good quality two-dimensional echocardiographic estimate of left atrial dimensions using the left atrial to aortic root ratio. Using a metal caliper system, P wave duration was measured to the nearest 10 milliseconds for six consecutive heart beats; data were then averaged for each dog. The accuracy of P wave duration in predicting left atrial enlargement was determined using a receiver operating characteristic analysis.
  
  
  RESULTS
  One hundred and fifty-six dogs were included in the study. Average P wave durations of 20, 30, 40 and 50 milliseconds yielded sensitivities of 100, 85, 68 and 40% and specificities of 0, 16, 64 and 93%, respectively, for the diagnosis of Left Atrial Enlargement by echocardiography. The estimated area under curve of the receiver operating characteristic curve was 0·70 (95% confidence interval: 0·60 to 0·80).
  
  
  CONCLUSIONS
  The diagnostic performance of P wave duration for identification of left atrial enlargement in dogs presents considerable limitations.
authors.affiliation: Department of Animal Pathology, University of Torino, via Leonardo da Vinci 44, 10095 Grugliasco (TO), Italy.
authors.forename: P
authors.initials: P
authors.lastname: Savarino
authors.forename: M
authors.initials: M
authors.lastname: Borgarelli
authors.forename: A
authors.initials: A
authors.lastname: Tarducci
authors.forename: S
authors.initials: S
authors.lastname: Crosara
authors.forename: N M
authors.initials: NM
authors.lastname: Bello
authors.forename: M L
authors.initials: ML
authors.lastname: Margiocco
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000175:diagnosis / Q000662:veterinary*; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D004562:Electrocardiography / Q000379:methods / Q000662:veterinary*; D005260:Female; D006325:Heart Atria / Q000473:pathology*; D008297:Male; D012372:ROC Curve; D015203:Reproducibility of Results