DeltaT50--a new method to assess temporal ventricular repolarization variability

J Electrocardiol. Jul-Aug 2011;44(4):477.e1-9. doi: 10.1016/j.jelectrocard.2011.04.010.

Abstract

Background: Increased beat-to-beat variability in cardiac repolarization time is a tentative risk marker of drug-induced torsades de pointes. We developed a new, automatic method based on the temporal variability of the T-wave down slope to assess this variability.

Method and results: Leads V(1) to V(6) of resting electrocardiograms were recorded in 42 healthy subjects (18-68 years, 22 men). The temporal variability at 50% of the T-wave down slope, deltaT50 (1.5 ± 0.41 milliseconds; range, 0.86-2.66 milliseconds), was measured with an accuracy of 1 millisecond on at least 9 pairs of electrocardiogram complexes with a signal-to-noise ratio more than 10 and changes in the R-R interval less than 150 milliseconds. The correlation between repeated measurements of deltaT50 was high. DeltaT50 was measured without corrections for age, sex, heart rate, T-wave amplitude, signal-to-noise ratio, R-R variability, and QTcF because none of these factors explained more than 4% of the within-subject deltaT50 variability.

Conclusion: The beat-to-beat repolarization variability was measured with high fidelity with the deltaT50 method and was a robust measure in healthy volunteers.

Publication types

  • Validation Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Arrhythmias, Cardiac / physiopathology
  • Electrocardiography*
  • Female
  • Heart Conduction System / physiology*
  • Humans
  • Linear Models
  • Male
  • Middle Aged
  • Reference Values
  • Time Factors