Beat-to-beat determinants of the beat-to-beat temporal and spatial variability of repolarization

J Electrocardiol. 2016 May-Jun;49(3):417-22. doi: 10.1016/j.jelectrocard.2016.01.007. Epub 2016 Jan 20.

Abstract

Background: The goal of this study was to compare the time series predictors of beat-to-beat variability in repolarization in healthy individuals.

Methods: Spatial QRS- and T-vector amplitudes, spatial QRS-T, RR' and TT' angles, RR' and QT intervals, and QRS- and T-loop roundness were measured on 453 consecutive sinus beats in 168 healthy subjects (mean age 39.8±15.6years; 50% men; 93% white). Panel time-series regression models were adjusted by age, sex, and race. Appropriate time series of ECG metrics served as predictors and outcomes.

Results: Increase in T-loop roundness index by 0.1 was associated with 1.1° (95%CI 0.9-2.2; P=0.048) increase in corresponding TT' angle. One unit increase in a respiration index was associated with 4ms (95%CI 0.6-7.0; P=0.021) increase in QT interval.

Conclusions: Spatial TT' angle and beat-to-beat variability in T-loop roundness represent intrinsic measures of repolarization variability. QT interval variability characterizes the effect of respiration and heart rate variability.

Keywords: QT interval; Repolarization; Repolarization variability; Spatial TT′ angle.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Algorithms
  • Computer Simulation
  • Diagnosis, Computer-Assisted / methods
  • Electrocardiography / methods*
  • Female
  • Heart Conduction System / physiology*
  • Heart Rate / physiology*
  • Heart Rate Determination / methods*
  • Humans
  • Male
  • Models, Cardiovascular*
  • Reference Values
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Vectorcardiography / methods*