title: Clinical predictors of head-up tilt test outcome during the nitroglycerin phase.
abstract: OBJECTIVE
  Nitrate-stimulated head-up tilt testing (HUT) is currently recommended to confirm the diagnosis of vasovagal syncope in subjects with syncope of unknown origin. Given the few data currently available, the aim of this study was to assess correlations between nitrate-induced HUT outcomes and the clinical characteristics of patients.
  
  
  METHODS
  Two hundred and thirty consecutive, otherwise healthy subjects with a history of recurrent unexplained syncope underwent HUT. After 10 min supine rest, they were tilted to 70 degrees , and the test was potentiated by the administration of 300 microg of nitroglycerin after 20 min.
  
  
  RESULTS
  Out of 178 subjects who underwent nitroglycerin administration during HUT, 95 fainted. At univariate Cox regression analysis, a reduced probability of VVS occurrence after nitrates was associated with greater systolic blood pressure and body mass index values, to male gender and smoking. At multivariate Cox regression analysis, only male gender (HR = 0.61; P = 0.039) and smoking (HR = 0.18; P = 0.001) remained significantly associated with HUT outcomes during the pharmacological phase of the test.
  
  
  CONCLUSIONS
  Smokers and males are less likely to faint after nitrate administration during HUT than non-smokers and females. Further studies should clarify the possibility of improving the diagnostic power of HUT in these patients.
authors: Cardiology Unit, Emergency and Organ Transplantation Department, University of Bari, Piazza Giulio Cesare 11, 70124 Bari, Italy. massimo.iacoviello@cardio.uniba.it
authors: Massimo
authors: M
authors: Iacoviello
authors: Cinzia
authors: C
authors: Forleo
authors: Pietro
authors: P
authors: Guida
authors: Marco Matteo
authors: MM
authors: Ciccone
authors: Sandro
authors: S
authors: Sorrentino
authors: Valentina
authors: V
authors: D'Andria
authors: Mariligia
authors: M
authors: Panunzio
authors: Stefano
authors: S
authors: Favale
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D005996:Nitroglycerin; D012044:Regression Analysis; D012907:Smoking / Q000503:physiopathology; D016683:Supine Position / Q000502:physiology; D019462:Syncope, Vasovagal / Q000175:diagnosis* / Q000503:physiopathology; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin