title: Seasonal variability of the QT dispersion in healthy subjects.
abstract: We studied the seasonal variability of QT dispersion in 25 healthy subjects, aged 36 +/- 5 (25 to 46) years. Four seasonal 12-lead rest electrocardiograms (ECGs) recorded at a double amplitude were performed at 25 mm/s at intervals of roughly 3 months. To avoid possible confusion from the circadian rhythm of QT dispersion, subsequent ECGs were recorded within 30 minutes of the reference summer one. The QT dispersion was calculated as the difference between the longest and the shortest mean QT intervals. There was a seasonal variability in the QT dispersion (P =.001), with the largest QT dispersion occurring in winter (66 +/- 21 ms) and the smallest one in spring (48 +/- 18 ms). In conclusion, there exists a seasonal variability of QT dispersion in healthy subjects and such variability should be taken into consideration in comparison of the QT dispersion.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan. wcvoonnn@giga.net.tw
authors.forename: W C
authors.initials: WC
authors.lastname: Voon
authors.forename: J C
authors.initials: JC
authors.lastname: Wu
authors.forename: W T
authors.initials: WT
authors.lastname: Lai
authors.forename: S H
authors.initials: SH
authors.lastname: Sheu
mesh_terms: D000328:Adult; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D012621:Seasons