title: T-wave morphology parameters based on principal component analysis reproducibility and dependence on T-offset position.
abstract: BACKGROUND
  T-wave morphology parameters based on principal component analysis (PCA) are candidate to better understand the relation between QT prolongation and torsades de pointes. We aimed to assess the repeatability and to determine the influence of T-end position on PCA parameters.
  
  
  METHODS
  Digital ECGs recorded from 30 subjects were used to assess short term (5 minutes), circadian and long-term (28 days) repeatability of PCA parameters. The T-end cursor position was moved backward and forward (+/- 8 ms) from its optimal position. We calculated QRS-T angle, PCA ratio, and T-wave residuum (TWR).
  
  
  RESULTS
  At long-term evaluation, coefficients of variation were 11.3 +/- 9.9%, 11.7 +/- 7.1%, and 23.0 +/- 22.0% for the QRS-T angle, PCA ratio, TWR, respectively. After moving the T-end cursor, repeatability was 0.42 +/- 0.2%, 1.00 +/- 1.04%, 4.0 +/- 4.2% for the same PCA parameters.
  
  
  CONCLUSIONS
  T-wave morphology parameters based on PCA are reproducible with the exception of TWR and QRS-T angle. In addition, PCA is robust, showing only little dependence on T-end cursor position. These data should be taken into account for safety pharmacology trials.
authors.affiliation: Cardiology Department, Lariboisière Hospital, APHP, Paris 7 University, France. fabrice.extramiana@lrb.aphp.fr
authors.forename: Fabrice
authors.initials: F
authors.lastname: Extramiana
authors.forename: Abdeddayem
authors.initials: A
authors.lastname: Haggui
authors.forename: Pierre
authors.initials: P
authors.lastname: Maison-Blanche
authors.forename: Rémi
authors.initials: R
authors.lastname: Dubois
authors.forename: Seiji
authors.initials: S
authors.lastname: Takatsuki
authors.forename: Philippe
authors.initials: P
authors.lastname: Beaufils
authors.forename: Antoine
authors.initials: A
authors.lastname: Leenhardt
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D025341:Principal Component Analysis; D015203:Reproducibility of Results; D012737:Sex Factors