title: Daily, weekly, monthly, and seasonal patterns in the occurrence of vasovagal syncope in an older population.
abstract: OBJECTIVE
  The aim of this study was to assess the frequency of vasovagal episodes over the day, week, month, and seasons.
  
  
  RESULTS
  This study was part of the multi-centre International Study on Syncope of Uncertain Etiology-2 (ISSUE-2), which included patients, aged 30 years or older, with severe neurally mediated syncope between June 2002 and July 2004. The Implantable Loop Recorder (ILR) was used to document the syncope-related ECG periods. For this study patients with recorded syncopal episodes after ILR-implantation was selected. At least one episode was documented in 106 patients. A higher number of episodes were documented during the morning than during other periods of the day (P < 0.01). There was no difference between various days of the week, episodes per month, or between seasons. There was no difference between age and gender groups, although elderly patients seemed to be responsible for the peak in the morning.
  
  
  CONCLUSIONS
  A circadian pattern in the frequency of vasovagal episodes exists, with a peak in the morning. This is in accordance with reports of diurnal variations in blood pressure and heart rate. No difference was observed in syncope distribution between days of the week, months, or seasons.
authors.affiliation: Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, 1100 DE, Amsterdam, The Netherlands. n.vandijk@amc.uva.nl
authors.forename: Nynke
authors.initials: N
authors.lastname: van Dijk
authors.forename: Mardi C
authors.initials: MC
authors.lastname: Boer
authors.forename: Tiziana
authors.initials: T
authors.lastname: De Santo
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Grovale
authors.forename: Arnaud J J
authors.initials: AJ
authors.lastname: Aerts
authors.forename: Lucas
authors.initials: L
authors.lastname: Boersma
authors.forename: Wouter
authors.initials: W
authors.lastname: Wieling
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012621:Seasons; D012737:Sex Factors; D013575:Syncope / Q000209:etiology*; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000453:epidemiology*; D013997:Time Factors; D014630:Vagus Nerve / Q000502:physiology*