title: Impaired autonomic function predicts dizziness at onset of paroxysmal atrial fibrillation.
abstract: BACKGROUND
  Paroxysmal atrial fibrillation is associated with various symptoms, including dizziness, which presumably reflects hemodynamic deterioration. Given the importance of the autonomic nervous system in mitigating the hemodynamic effect of atrial fibrillation, we hypothesized that autonomic function would be predictive of the severity of dizziness.
  
  
  METHODS
  The study group comprised 73 patients with paroxysmal atrial fibrillation (mean age 54.1 years, 51 males). Forty-three (59%) patients had lone atrial fibrillation. Mean ventricular rate during atrial fibrillation was 99+/-16 beats/min. On average, patients had a 3-year history of one paroxysm per week lasting 2 h. Autonomic function was assessed using autonomic function tests, including noninvasive measurement of baroreflex sensitivity. Head up tilting was used to test vasovagal reactivity. Severity of dizziness at onset of atrial fibrillation was quantified by the patients using a five-point scale (1=none; 2=light; 3=mild; 4=moderate; and 5=severe). Multivariate analysis was performed to identify the independent predictors of the severity of dizziness.
  
  
  RESULTS
  Mean severity of dizziness was 3.36+/-1.65. Multivariate predictors of moderate-to-severe dizziness as opposed to none-to-mild dizziness were a low 30-15 ratio after standing up and low baroreflex sensitivity. Though syncope was never reported nine patients showed a full vasovagal response during head up tilting.
  
  
  CONCLUSIONS
  It is concluded that dizziness in patients with "treated" atrial fibrillation in the setting of none to mild structural heart disease is predicted by impaired autonomic function. Vasovagal reactivity appears not to be involved in this connection.
authors.affiliation: Department of Cardiology, Thorax Center, University Hospital Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands. m.p.van.den.berg@thorax.azg.nl
authors.forename: M P
authors.initials: MP
authors.lastname: van den Berg
authors.forename: R J
authors.initials: RJ
authors.lastname: Hassink
authors.forename: A E
authors.initials: AE
authors.lastname: Tuinenburg
authors.forename: J D
authors.initials: JD
authors.lastname: Lefrandt
authors.forename: P J
authors.initials: PJ
authors.lastname: de Kam
authors.forename: H J
authors.initials: HJ
authors.lastname: Crijns
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications* / Q000503:physiopathology*; D001342:Autonomic Nervous System Diseases / Q000150:complications* / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D004244:Dizziness / Q000209:etiology* / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D014636:Valsalva Maneuver / Q000502:physiology; D014939:Work of Breathing / Q000502:physiology