Author + information
- Received February 23, 1994
- Revision received September 14, 1994
- Accepted October 24, 1994
- Published online March 15, 1995.
- Mark A. Wood, MDa,*,
- Pippa M. Simpson, PhDa,
- Wendy B. London, BSa,
- Bruce S. Stambler, MD, FACCa,
- John M. Herre, MD, FACC*,
- Robert C. Bernstein, MD, FACC* and
- Kenneth A. Ellenbogen, MD, FACCa
- ↵*Address for correspondence: Dr. Mark A. Wood, Medical College of Virginia, MCV Box 980053, Richmond, Virginia 23298.
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.
This study was supported by Cardiac Pacemakers, Inc., Minneapolis, Minnesota and Telectronics Pacing Systems. Englewood, Colorado.
- Received February 23, 1994.
- Revision received September 14, 1994.
- Accepted October 24, 1994.
- American College of Cardiology