Diurnal Variation of QT Dispersion in Patients With and Without Coronary Artery Disease

Abstract

QT dispersion defined as interlead QT variability in a 12-lead electrocardiogram was proposed by Day and associates as a simple method to evaluate the repolarization heterogenicity of the ventricular myocardium. The frequency of onset of myocardial infarction and sudden death has been reported to have a circadian variation, with a peak incidence in the early morning hours. The authors investigated whether there is diurnal variation of QT interval and QT interval dispersion in healthy subjects and in patients with coronary artery disease. The study population consisted of two groups. Group I consisted of 62 subjects without coronary artery disease and group II consisted of 82 patients with coronary artery disease. Twelve-lead ECG was recorded for each patient in the morning (between 7 AM and 8 AM), afternoon (between 3 PM and 5 PM) and at night (between 11 PM and 1 AM), on the day after performance of coronary angiography. QTc dispersion was significantly higher in patients with coronary artery disease than in healthy subjects in the morning hours and afternoon (p<0.001). Although the differences were much prominent in group I than group II, both QTc dispersion of morning and afternoon were significantly greater than those at night. There were no statistically significant differences between group I and group II at nighttime with respect to maximum QTc, minimum QTc intervals, and QTc dispersion (p>0.05). In conclusion, QT dispersion shows diurnal variation with an increase in the morning hours in both patients with coronary artery disease and subjects without coronary artery disease. The mechanism of diurnal variation of QT dispersion in patients with coronary artery disease is quite different from that of healthy subjects.

Circadian Variation in QT Dispersion Determined from a 12‐Lead Holter Recording: A Methodological Study of an Age‐ and Sex‐Stratified Group of Healthy Subjects

“…Using all 12 leads available Yetkin et al 19 and Batur et al 20 observed a significantly higher QTc dispersion in the morning and daytime compared to nighttime, whereas Lee et al 10 agreed with our observation that QT dispersion had a higher value at night compared to daytime. Malik et al 23 did not find any significant difference between day and night in a 12‐lead Holter recording.…”

“…Circadian variation of QT dispersion in healthy subjects has been suggested by Ishida et al, 8 Molnar et al, 9 Lee et al, 10 Yetkin et al, 19 Batur et al, 20 Bilan et al, 21 and Bonnemeier et al, 22 but the results are contradictory and the studies have different setups in respect to number of leads used, measurement frequency, and whether heart rate correction of QT dispersion is used or not.…”

Diurnal variation and dispersion in QT interval in cirrhosis: Relation to haemodynamic changes

“…However, no previous study has addressed the possibility that the QT C and QT dispersion might change from daytime to night-time. A finding observed in patients with ischemic heart disease [39,40]. This might be caused by 24-h variation of autonomic tone, circulatory status, and respiratory and oxygen demand.…”

QT Intervals and QT Dispersion Determined from a 12‐Lead 24‐Hour Holter Recording in Patients with Coronary Artery Disease and Patients with Heart Failure

“…The circadian variation in QT dispersion has been investigated in healthy subjects, 9,10 patients with coronary artery disease, 11,12 and congestive heart failure 13,14 with conflicting observations. These studies vary in selection of leads and timing of measurements and therefore the results are difficult to compare.…”