title: Prediction of head-up tilt test result: is it possible?
abstract: BACKGROUND
  The determination of early, accurate, predictive criteria for a positive result would permit a reduction in the duration of the head-up tilt testing (HUTT). Previous studies propounded that existence of early sympathetic overreactivity (rapid and sustained increase in heart rate) during HUTT predicts positive result. However, the exact value of this variable is unknown. We analyzed the early heart rate (HR) responses to HUTT and evaluated their ability to predict HUTT result.
  
  
  METHODS
  Consecutive patients referred to the syncope unit of our center for recurrent unexplained syncope were studied.
  
  
  RESULTS
  We studied 189 consecutive patients and 67 (35%) patients had a negative HUTT; 122 (65%) patients had a positive HUTT. The early HR increase was defined as the maximum HR during the first 10 minutes of tilting minus the resting HR before tilting. The receiver-operator curves (ROCs) show the overall performance of the HR changes for predicting the HUTT result. For all variables, area under the ROC curve (AUC) was nearly equivalent to 0.50 and early HR increase was not a predictor of the negative result of HUTT (AUC = 0.546). Also there was no any significant correlation between the magnitude of early HR increase and patient age (r =-0.03, P = 0.76).
  
  
  CONCLUSIONS
  The results suggest that the early increase in HR during the first 10 minutes of the HUTT may not be a useful parameter for predicting the test result. Many factors, such as late exaggeration in sympathetic activity during HUTT and age-dependent reduction in baroreflex sensitivity, may attenuate the predictive value of early HR increase.
authors.affiliation: Department of Cardiology, Central Hospital, Izmir, Turkey. droturk@yahoo.com
authors.forename: Ugur
authors.initials: U
authors.lastname: Turk
authors.forename: Emin
authors.initials: E
authors.lastname: Alioglu
authors.forename: Bahadir
authors.initials: B
authors.lastname: Kirilmaz
authors.forename: Hamza
authors.initials: H
authors.lastname: Duygu
authors.forename: Nurullah
authors.initials: N
authors.lastname: Tuzun
authors.forename: Istemihan
authors.initials: I
authors.lastname: Tengiz
authors.forename: Mehdi
authors.initials: M
authors.lastname: Zoghi
authors.forename: Ertugrul
authors.initials: E
authors.lastname: Ercan
mesh_terms: D000328:Adult; D000367:Age Factors; D017704:Baroreflex; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000503:physiopathology; D018667:Tilt-Table Test / Q000379:methods*