title: Circadian variation of symptomatic paroxysmal atrial fibrillation. Data from almost 10 000 episodes.
abstract: OBJECTIVE
  To determine the circadian rhythm of paroxysmal atrial fibrillation in a very large outpatient population.
  
  
  RESULTS
  We reviewed all emergency telephone calls received in Shahal (a medical service covering 44 000 subscribers), from 1987 to 1997. Patients were included if new-onset atrial fibrillation was recorded. During this study period, 9989 episodes of paroxysmal atrial fibrillation were recorded. The time of onset was not uniformly distributed throughout the 24 h period. Instead, the distribution of arrhythmic episodes showed a double peak, with a significant increase in the number of episodes in the morning and a second rise in the evening (P<0.001). A non-uniform weekly distribution of events was also noted, with substantially fewer episodes on Saturdays (P<0.001). Finally, more arrhythmias occurred during the last months of each year (P<0.001).
  
  
  CONCLUSIONS
  The onset of paroxysmal atrial fibrillation does not occur randomly. The large patient population in the present study suggests that the circadian rhythm of paroxysmal atrial fibrillation is similar to that described for other cardiovascular diseases, with clustering of events in the morning and (to a lesser degree) late in the evening. Weekly and yearly circadian patterns are also prominent.
authors.affiliation: Department of Cardiology, Sourasky, Tel Aviv and Sheba, Israel. viskin_s@netvision.net.il
authors.forename: S
authors.initials: S
authors.lastname: Viskin
authors.forename: M
authors.initials: M
authors.lastname: Golovner
authors.forename: N
authors.initials: N
authors.lastname: Malov
authors.forename: R
authors.initials: R
authors.lastname: Fish
authors.forename: I
authors.initials: I
authors.lastname: Alroy
authors.forename: Y
authors.initials: Y
authors.lastname: Vila
authors.forename: S
authors.initials: S
authors.lastname: Laniado
authors.forename: E
authors.initials: E
authors.lastname: Kaplinsky
authors.forename: A
authors.initials: A
authors.lastname: Roth
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology*; D016000:Cluster Analysis; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007557:Israel / Q000453:epidemiology; D008297:Male; D013997:Time Factors