[Daily activities and circadian variation of ventricular tachyarrhythmias in patients with implanted defibrillator]

Acute cardiovascular events may be triggered by physical and mental stress. Does also the typical circadian variation of arrhythmia recurrence (morning peak of events) in patients with implanted cardioverter-defibrillator correlate with the individual circadian variation of physical and mental daily activities?

In 29 consecutive patients with a minimum of three documented ventricular tachyarrhythmias after defibrillator implantation the circadian variation of habitual daily activities was determined in a standardized interview and compared to the individual circadian variation of arrhythmic events saved in the defibrillator event memory during long-term follow-up.

The habitually highest physical and mental activity was determined during the time period with most arrhythmic events in 55 % and 23 % of patients, respectively. A comparison of the level of activity during the time period with the highest event frequency to the mean activity level during the rest of the day (without sleeping time) revealed significantly higher physical activity during the time of day with the highest arrhythmia recurrence. There was a positive correlation between circadian variation of arrhythmic events and the sum of all activities (r = 0.34, p < 0.05) and physical activities alone (r = 0.25, p = 0.056) while a relationship to mental activities alone could not be shown (r = 0.02, p = 0.84)

The circadian variation of acute cardiovascular events may be discussed as an essential factor influencing the circadian variation of habitual daily activities in patients with cardiac disease.