title: False positive responses to head-up tilt testing in elderly patients with paroxysmal atrial fibrillation.
abstract: The autonomic nervous system (ANS) plays a role as a modulator in the pathogenesis of paroxysmal atrial fibrillation (PAF). The clinical pattern of vagally mediated PAF has been observed mainly in young patients. Neurocardiogenic responses during orthostatic stress are related to autonomic reflexes in which the vagal influence predominates.
  
  
  OBJECTIVE
  To evaluate the susceptibility of elderly patients with PAF to activation of vasovagal syncope mechanisms.
  
  
  METHODS
  We performed passive head-up tilt testing (HUT) in 34 patients (62% women, aged 72 +/- 7 years), with > or = 1 year of clinical history of PAF--19 without structural heart disease, 11 with hypertensive heart disease and 4 with coronary artery disease (who had no previous myocardial infarction, had undergone myocardial revascularization, and had no documented ischemia) (PAF group), and compared the results with those obtained in a group of 34 age-matched patients (53% women, aged 74 +/- 6 years), who underwent HUT due to recurrent syncope (Sc group). In this group, 21 had no documented heart disease and none had a clinical history of AF. There was no diabetes, congestive heart failure or syncope in the PAF group. After a supine resting period, the subjects were tilted at 70 degrees for 20 minutes while in sinus rhythm. No provocative agents were used to complement the HUT. ECG and blood pressure were continuously monitored (Task Force Monitor, CNSystems). The test was considered positive when syncope or presyncope occurred with bradycardia and/or arterial hypotension. Abnormal responses were classified as cardioinhibitory, vasodepressor or mixed.
  
  
  RESULTS
  HUT was positive in seven patients of the PAF group--vasodepressor response in five and mixed in two (20.5% of the total; 26.3% of those without heart disease)--and in eight patients (vasodepressor in six and mixed in two) of the Sc group (p=NS). During HUT, three patients of the PAF group had short periods of self-limited PAF (in one, after vasodepressor syncope). There were no differences in gender distribution, age or heart disease. No cardioinhibitory responses or orthostatic hypotension were observed.
  
  
  CONCLUSIONS
  In elderly patients with PAF, a significant number of false positive results during passive HUT may be expected, suggesting increased vasovagal reactions despite aging. This suggests that ANS imbalances may be observed in this population.
authors.affiliation: Serviço de Cardiologia, Hospital Santa Marta Hospital, Lisboa, Portugal. mmartinsoliveira@gmail.com
authors.forename: Mário Martins
authors.initials: MM
authors.lastname: Oliveira
authors.forename: Joana
authors.initials: J
authors.lastname: Feliciano
authors.forename: Ana Teresa
authors.initials: AT
authors.lastname: Timóteo
authors.forename: Nogueira
authors.initials: N
authors.lastname: da Silva
authors.forename: Eduardo
authors.initials: E
authors.lastname: Antunes
authors.forename: Sofia
authors.initials: S
authors.lastname: Silva
authors.forename: Sandra
authors.initials: S
authors.lastname: Alves
authors.forename: Luís
authors.initials: L
authors.lastname: Silva-Carvalho
authors.forename: Rui
authors.initials: R
authors.lastname: Ferreira
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001919:Bradycardia / Q000209:etiology; D016022:Case-Control Studies; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007022:Hypotension / Q000209:etiology; D008297:Male; D019462:Syncope, Vasovagal / Q000209:etiology / Q000503:physiopathology*; D018667:Tilt-Table Test / Q000009:adverse effects / Q000379:methods*