title: Is baseline autonomic tone associated with new onset atrial fibrillation?: Insights from the framingham heart study.
abstract: BACKGROUND
  Recent reports have indicated that autonomic tone fluctuations measured by heart rate variability (HRV) precede episodes of paroxysmal atrial fibrillation (AF). Little is known about the impact of baseline autonomic tone and the development of new onset AF in a population-based cohort. The purpose of this study was to assess the role of HRV as a predictor of new onset AF.
  
  
  METHODS
  Ambulatory ECG recordings obtained from the Framingham Heart Study subjects attending a routine examination were processed for HRV. The HRV variables analyzed included standard deviation of normal R-R intervals (SDNN), low frequency power (LF), high frequency power (HF), and LF/HF ratio. There were 1434 women and 1142 men (54 +/- 14.1 years) eligible for the study.
  
  
  RESULTS
  In 12 years of follow-up, 65 women and 67 men had new onset AF. The study had 80% power to detect a hazard ratio (HR) of 1.3 per standard deviation (SD) decrement in HRV. A one SD decrement in log LF/HF was associated with increased risk of developing AF (HR = 1.23; 95% confidence intervals (CI) = 1.06-1.44) in age- and sex-adjusted models; the association was no longer significant (HR = 1.15; 95% CI = 0.98-1.35) after adjusting for potential confounders.
  
  
  CONCLUSIONS
  Autonomic dysregulation at baseline, as reflected by an altered HRV is associated with risk of AF; however, this association does not persist after adjusting for potential confounders. Much of the apparent association between HRV and AF is mediated by traditional risk factors.
authors.affiliation: National Heart, Lung & Blood Institute's Framingham Heart Study, Framingham, Massachusetts, USA. jsingh@partners.org
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
authors.forename: Martin G
authors.initials: MG
authors.lastname: Larson
authors.forename: Daniel
authors.initials: D
authors.lastname: Levy
authors.forename: Jane C
authors.initials: JC
authors.lastname: Evans
authors.forename: Hisako
authors.initials: H
authors.lastname: Tsuji
authors.forename: Emelia J
authors.initials: EJ
authors.lastname: Benjamin
mesh_terms: D000328:Adult; D001281:Atrial Fibrillation / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors