title: Comparison between tilt-table testing results performed during different periods of the day.
abstract: OBJECTIVE
  To evaluate the influences of circadian variations on tilt-table testing (TTT) results by comparing the positivity rate of the test performed during the morning with that of the test performed in the afternoon and to evaluate the reproducibility of the results in different periods of the day.
  
  
  METHODS
  One hundred twenty-three patients with recurrent unexplained syncope or near-syncope referred for TTT were randomized into 2 groups. In group I, 68 patients, TTT was performed first in the afternoon and then in the morning. In group II, 55 patients, the test was performed first in the morning and then in the afternoon.
  
  
  RESULTS
  The TTT protocol was the prolonged passive test, without drug sensitization. Twenty-nine (23.5%) patients had a positive result in at least one of the periods. The positivity rate for each period was similar: 20 (16.2%) patients in the afternoon and 19 (15.4%) in the morning (p=1.000). Total reproducibility (positive/positive and negative/negative) was observed in 49 (89%) patients in group I and in 55 (81%) in group II. Reproducibility of the results was obtained in 94 (90.4%) patients with first negative tests but in 10 (34%) patients with first positive tests.
  
  
  CONCLUSIONS
  TTT could be performed during any period of the day, and even in the 2 periods to enhance positivity. Considering the low reproducibility rate of the positive tests, serial TTT to evaluate therapeutic efficacy should be performed during the same period of the day.
authors.affiliation: Heart Institute, São Paulo University, São Paulo, SP, Brazil.
authors.forename: Tan Chen
authors.initials: TC
authors.lastname: Wu
authors.forename: Denise
authors.initials: D
authors.lastname: Hachul
authors.forename: Mauricio
authors.initials: M
authors.lastname: Scanavacca
authors.forename: Eduardo
authors.initials: E
authors.lastname: Sosa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D002940:Circadian Rhythm; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D015203:Reproducibility of Results; D019462:Syncope, Vasovagal / Q000209:etiology*; D018667:Tilt-Table Test