Circadian pattern of ventricular tachyarrhythmias in patients with implantable cardioverter-defibrillators

J Am Coll Cardiol. 1995 Mar 15;25(4):901-7. doi: 10.1016/0735-1097(94)00460-8.


Objectives: This study examined the temporal patterns of ventricular tachycardia detections by implantable cardioverter-defibrillators for circadian variability.

Background: Previous studies of circadian arrhythmia patterns have been methodologically limited by very brief observational periods. Late-generation implantable cardioverter-defibrillators accurately record the times of arrhythmia detections during unlimited follow-up.

Methods: Forty-three patients with late-generation implantable cardioverter-defibrillators were followed up for 226 +/- 179 days (mean +/- SD). The times of all recorded episodes of ventricular tachyarrhythmias were retrieved from the data log of each device during follow-up.

Results: The weighted distribution of 830 ventricular tachyarrhythmia episodes from the 43 patients fit a single harmonic sine curve model with a peak between 2 and 3 P.M. (95% confidence interval 1:13 to 4:13 P.M., R = 0.75, p < 0.05). The distributions of spontaneously terminating episodes, episodes receiving device therapy, episodes receiving shocks and episodes in the absence of antiarrhythmic therapy also fit the sine curve model (all R = 0.53 and 0.73, all p < 0.05), all with peak frequencies between 2:08 and 3:09 P.M. and 95% confidence intervals for peak frequencies between 11:38 A.M. and 5:07 P.M. Episodes recorded during continuous antiarrhythmic drug therapy did not fit the model (p > 0.05).

Conclusions: The distribution of ventricular tachyarrhythmias detected by late-generation implantable cardioverter-defibrillators follows a circadian pattern, with a peak tachycardia frequency between noon and 5 P.M. This pattern was not observed in patients receiving antiarrhythmic drug therapy. Knowledge of circadian periodicity for these events has implications for patient management.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Anti-Arrhythmia Agents / therapeutic use
  • Circadian Rhythm*
  • Defibrillators, Implantable*
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Tachycardia, Ventricular / drug therapy
  • Tachycardia, Ventricular / physiopathology*
  • Tachycardia, Ventricular / therapy


  • Anti-Arrhythmia Agents