Circadian and gender effects on repolarization in healthy adults: A study using harmonic regression analysis: ORIGINAL ARTICLES

Kenneth A. Mayuga, Emil Thattassery, Taresh Taneja, Juhana Karha, Haris Subacius, Jeffrey Goldberger, Alan Kadish

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background: Sudden cardiac death and myocardial infarction have a circadian variation with a peak incidence in the early morning hours. Increased dispersion of repolarization facilitates the development of conduction delay necessary to induce sustained arrhythmia. Both QT-dispersion and T-wave peak to T-wave end (TpTe) have been proposed as markers of dispersion of myocardial repolarization. Methods: Forty healthy adults (20 women), age 35-67 years old, with normal EKGs, echocardiograms, stress tests, and tilt-table tests were analyzed during a 27-hour hospital stay. EKGs were done at eight different time points. QT-intervals, QT-dispersion, and TpTe were measured at each time point. Harmonic regression was used to model circadian periodicity, P < 0.05 was considered significant. Results: The composite QT-interval was longer in women than in men (416 ± 17 msec vs 411 ± 20 msec, respectively, P = 0.006). The QT-dispersion among all leads was greater in men than women (37 ± 13 msec vs 30 ± 11 msec, respectively, P < 0.0001); a similar difference was found in the precordial leads. Harmonic regression showed that QT-dispersion had a significant circadian variation, primarily in men. In men, the maximum QT-dispersion occurred at 6 AM (45 ± 15 msec). TpTe also had a significant circadian variation that was not affected by gender in the majority of leads. Conclusions: A circadian variation exists in the dispersion of myocardial repolarization, as measured by both TpTe and QT-dispersion. Men and women have a different circadian variation pattern. Further studies regarding the mechanisms and clinical implications are needed. Ann Noninvasive Electrocardiol 2010;15(1):3-10

Original languageEnglish (US)
Pages (from-to)3-10
Number of pages8
JournalAnnals of Noninvasive Electrocardiology
Issue number1
StatePublished - Jan 2010
Externally publishedYes


  • Circadian variation
  • QT-dispersion
  • Repolarization

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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