Weekly Variation of the QT Dispersion in Healthy Subjects and in Patients with Coronary Heart Disease

Abstract

Background: A circadian and seasonal variation of QT dispersion (QTd) has been shown in healthy individuals. Nevertheless, no data exist regarding the weekly influences on the QTd in healthy individuals and in patients with coronary heart disease (CHD). Design: This study was designed to determine whether there is a weekly variability of QTd in healthy individuals and in patients with CHD. Methods: In this prospective registry study, 53 patients with documented CHD and 57 healthy control subjects were involved. Resting electrocardiograms (ECGs) with double amplitude were recorded at a speed of 50 mm/s on Monday and Friday mornings. QT intervals were measured and QTd were determined by calculating the difference between maximum and minimum QT intervals. Then, rate-corrected QTd (QTcd) were calculated using Bazett’s formula. Results: There was a significant weekly variation of QTd in control subjects (39.3 ± 6.3 vs. 36.2 ±6.1 ms) (p < 0.05) and in patients (56 ± 7.3 vs. 47.4 ± 5.4 ms) (p < 0.0001). There was also a significant weekly variation of QTcd both in control subjects (33 ± 5.3 vs. 30.7 ± 5.6 ms) (p < 0.05) and in patients (47.4 ± 6.4 vs. 41.9 ± 5.4 ms) (p < 0.0001). Conclusions: There is a weekly variation of QTd and QTcd in healthy individuals and in patients with CHD, both with a Monday preference. This fact should be taken into consideration during the chronopharmacological treatment or advisal of primary or secondary preventive measures to these subjects or patients.

Büro çalışanlarında pazartesi kaygısı / Monday anxiety in office workers

“…Physical diseases of the participants or their ex-colleagues which occurred on Mondays were not asked in our study. Some authors related physical diseases occurred on Monday with cultural differences in eating habits which may vary on different days of the week (4,10,25). Weekly holidays may vary in different societies so it should be kept in mind that importance of Monday is due to its being the first day of the week (1,26).…”

“…Some studies paid attention to first hours of the day and especially 8-9 am of Mondays related with the occurrence of heart attacks and strokes (10,11). Physiological changes and increased autonomic nervous system activity in the morning hours may have a role in heart attack and stroke occurrence in people working daytime in the week.…”

“…Physiological changes and increased autonomic nervous system activity in the morning hours may have a role in heart attack and stroke occurrence in people working daytime in the week. Increase in physical and mental activity needed when passing from freedom state of weekend holiday to Monday which is the first day of planned and stressful activities was also found responsible for heart attack and stroke (3)(4)(5)(6)(7)(8)(9)(10).…”

Geographic-Time Distribution of Ambulance Calls in Singapore: Utility of Geographic Information System in Ambulance Deployment (CARE 3)

“…24 Similar patterns have been observed in acute myocardial infarction, 28-34 stroke 22,35 and pulmonary embolism. 36 Various explanations for this effect that have been proposed include circadian variations in the autonomic nervous system, 37 variations in electrical activity, [38][39][40] vascular changes 41,42 and hormonal/metabolic fluctuations. 43 It is interesting that our ambulance calls also seem to correspond to these circadian rhythms.…”