title: Long-Term, Competitive Swimming and the Association with Atrial Fibrillation.
abstract: BACKGROUND
  Endurance exercise plays a role in cardiovascular risk reduction, but may also be a risk factor for atrial fibrillation. This study was performed to assess the prevalence of atrial fibrillation in a population of long-term, competitive swimmers compared with patients within an internal medicine clinic with known risk factors for atrial fibrillation such as diabetes mellitus and hypertension.
  
  
  METHODS
  This cross-sectional study utilized survey data comparing the prevalence of atrial fibrillation in swimmers to a general internal medicine population. A multi-national group of swimmers over the age of 60 were surveyed, and a chart review was performed on a random sample of age-matched internal medicine patients. The primary outcome was the diagnosis of atrial fibrillation. Univariate analysis was used for means of proportions of the responses, and a multivariate logistic regression analysis was performed with diagnosis of atrial fibrillation as the dependent variable.
  
  
  RESULTS
  Forty-nine swimmers completed surveys and 100 age-matched internal medicine patients underwent chart review. Swimmers reported atrial fibrillation in 13 cases (26.5 %) compared to 7 (7 %) in the comparison group (p = 0.001). A diagnosis of hypertension or diabetes mellitus was present in 23 (46.9 %) and 1 (2 %) of the swimmers, respectively, as compared to 72 (72 %, p = 0.003) and 32 (32 %, p < 0.001) in the comparison group. Age, presence of diabetes mellitus, and swimming history were variables included in the logistic regression, in relation to atrial fibrillation. Swimming was associated with an odds ratio of 8.739 (95 % CI 2.290 to 33.344, p = 0.015).
  
  
  CONCLUSIONS
  Long-term, competitive swimmers have an increased prevalence of atrial fibrillation compared to internal medicine patients, despite the higher burden of diabetes mellitus and hypertension in the internal medicine group.
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1240, Charleston, SC, 29425, USA. schrein@musc.edu.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Schreiner
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1240, Charleston, SC, 29425, USA.
authors.forename: Brad A
authors.initials: BA
authors.lastname: Keith
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1240, Charleston, SC, 29425, USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Abernathy
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1240, Charleston, SC, 29425, USA.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Division of General Internal Medicine, Department of Medicine, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1240, Charleston, SC, 29425, USA.
authors.forename: Walter A
authors.initials: WA
authors.lastname: Brzezinski
keywords: Atrial fibrillation; Competitive swimming; Endurance exercise; Swimming