title: Impaired heart rate recovery is associated with new-onset atrial fibrillation: a prospective cohort study.
abstract: BACKGROUND
  Autonomic dysfunction appears to play a significant role in the development of atrial fibrillation (AF), and impaired heart rate recovery (HRR) during exercise treadmill testing (ETT) is a known marker for autonomic dysfunction. However, whether impaired HRR is associated with incident AF is unknown. We studied the association of impaired HRR with the development of incident AF, after controlling for demographic and clinical confounders.
  
  
  METHODS
  We studied 8236 patients referred for ETT between 2001 and 2004, and without a prior history of AF. Patients were categorized by normal or impaired HRR on ETT. The primary outcome was the development of AF. Cox proportional hazards modeling was used to control for demographic and clinical characteristics. Secondary analyses exploring a continuous relationship between impaired HRR and AF, and exploring interactions between cardiac medication use, HRR, and AF were also conducted.
  
  
  RESULTS
  After adjustment, patients with impaired HRR were more likely to develop AF than patients with normal HRR (HR 1.43, 95% confidence interval (CI) 1.06, 1.93). In addition, there was a linear trend between impaired HRR and AF (HR 1.05 for each decreasing BPM in HRR, 95% CI 0.99, 1.11). No interactions between cardiac medications, HRR, and AF were noted.
  
  
  CONCLUSIONS
  Patients with impaired HRR on ETT were more likely to develop new-onset AF, as compared to patients with normal HRR. These findings support the hypothesis that autonomic dysfunction mediates the development of AF, and suggest that interventions known to improve HRR, such as exercise training, may delay or prevent AF.
authors.affiliation: Cardiology Section, Denver VAMC, Denver, CO, USA. thomas.maddox@va.gov
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Maddox
authors.forename: Colleen
authors.initials: C
authors.lastname: Ross
authors.forename: P Michael
authors.initials: PM
authors.lastname: Ho
authors.forename: David
authors.initials: D
authors.lastname: Magid
authors.forename: John S
authors.initials: JS
authors.lastname: Rumsfeld
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000503:physiopathology / Q000517:prevention & control; D001342:Autonomic Nervous System Diseases / Q000453:epidemiology* / Q000503:physiopathology; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000706:statistics & numerical data; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D016016:Proportional Hazards Models; D011446:Prospective Studies; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*
chemical_list: D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors