title: A prospective study of excessive postural heart rate change on head-up tilt.
abstract: OBJECTIVE
  Healthy subjects with asymptomatic postural tachycardia (≥30 bpm) at baseline were evaluated over a 1-year period to determine whether they developed orthostatic symptoms.
  
  
  METHODS
  Subjects were evaluated at baseline and at 1 year using the autonomic reflex screen and autonomic symptom profile (ASP).
  
  
  RESULTS
  Heart rate increment on HUT did not differ at baseline (40.6 ± 7.5 bpm) or at 1 year (37.1 ± 11.1 bpm; n = 26; p > 0.05). Orthostatic symptoms measured by the ASP did not reveal significant orthostatic dysfunction throughout follow-up (baseline, 7.88 ± 7.61; 1 year, 9.04 ± 6.64; n = 26; p > 0.05). The ten autonomic domains of the ASP did not reveal a change in autonomic symptoms from baseline (13.56 ± 13.66) to 1-year follow-up (15.12 ± 11.62; n = 26; p > 0.05). Cardiovagal function was unchanged between baseline and follow-up for both heart rate variability to deep breathing (baseline, 23.9 ± 11.6 bpm; 1 year, 23.0 ± 9.3 bpm; n = 26; p > 0.05) and Valsalva ratio (baseline, 2.16 ± 0.39; 1 year, 2.15 ± 0.33; n = 26; p > 0.05).
  
  
  CONCLUSIONS
  These findings further argue that heart rate criteria (≥30 bpm) for Postural Tachycardia Syndrome (POTS) are not appropriate in younger individuals and higher postural heart rates do not predispose individuals to the development of POTS.
authors.affiliation: Department of Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, Rm. C7-131, 339 Windermere Road, London, ON, N6A 5A5, Canada.
authors.forename: James C
authors.initials: JC
authors.lastname: Corkal
authors.forename: Kurt
authors.initials: K
authors.lastname: Kimpinski
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D054972:Postural Orthostatic Tachycardia Syndrome / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D013610:Tachycardia / Q000503:physiopathology*; D018667:Tilt-Table Test; D055815:Young Adult