QT dispersion, T-wave projection, and heterogeneity of repolarization in patients with coronary artery disease Academic Article Article uri icon

Overview

MeSH Major

  • Advisory Committees
  • American Heart Association
  • Cardiology
  • Myocardial Ischemia
  • Societies, Medical

abstract

  • The clinically useful prognostic value of precordial QT dispersion in patients with heart disease is generally attributed to its measurement of regional heterogeneity of ventricular repolarization. However, when repolarization is abnormal, differences in measured QT intervals might result simply from variation in projection of the T-wave loop. To provide insight into the mechanism of QT dispersion, we used an analog device to transform conventional 12-lead electrocardiograms (ECGs) of 78 patients to derived 12-lead ECGs based on the heart vector. Because the electrical activity of the heart is represented by a single dipole, all QT dispersion in the transformed ECGs results from variation in projection of the T-wave loop and cannot be due to local heterogeneity of repolarization. Measured as the difference between the longest and shortest precordial QT intervals, QT dispersion in the derived ECGs, with no local heterogeneity of repolarization, was 53 +/- 49 ms (mean +/- SD). QT dispersion in these derived ECGs was similar in magnitude to that measured from the original standard 12-lead ECGs in these patients (49 +/- 23 ms, p = NS). Therefore, the precordial QT dispersion measured from standard ECGs of patients with coronary artery disease can be explained by interlead variation in precordial projection of the T-wave loop. Although regional heterogeneity might still contribute to precordial repolarization findings and to prognosis, this is not required to explain the QT dispersion observed in patients with coronary artery disease. Therefore, QT interval dispersion is not equivalent to heterogeneity of repolarization.

publication date

  • January 15, 2001

Research

keywords

  • Academic Article

Identity

Digital Object Identifier (DOI)

  • 10.1016/S0002-9149(00)01306-0

PubMed ID

  • 11152829

Additional Document Info

start page

  • 148

end page

  • 51

volume

  • 87

number

  • 2