Sport practice and the risk of lone atrial fibrillation: A case–control study

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Abstract

Background

Lone atrial fibrillation (LAF) is characterized by the presence of atrial fibrillation in the absence of structural heart disease or other identifiable cause of arrhythmia. In a recent study, we reported sport practice to be more frequent in LAF patients than in the general population. The aim of the study was to determine the association between sport practice and the prevalence of LAF in men.

Methods

An age-matched case–control study was designed. Cases were identified from consecutive patients who attended an outpatient clinic; 51 men with LAF were included, 20 of them with vagal characteristics. Controls were selected from the general population (n = 109). A questionnaire to assess former and current sport practice and the number of lifetime hours of sport practice was administered. Conditional logistic regression was used for statistical analysis.

Results

The proportion of patients with LAF who reported current sport practice (31%) was higher than that observed in controls (14%). In the logistic regression, current practice of sport was associated with a higher prevalence of LAF (OR = 3.13; 95% CI: 1.39–7.05). The practice of more than 1500 lifetime hours of sport appears to be the threshold for the observed association. Current practice of sport with a lifetime practice greater than 1500 h was associated with LAF (OR = 2.87; 95% CI: 1.20–6.91).

Conclusion

In men, the combination of current and prolonged lifetime sport practice is associated with higher risk of LAF.

Introduction

Lone atrial fibrillation (LAF) is characterized by the presence of atrial fibrillation in the absence of structural heart disease or other identifiable cause of arrhythmia, such as hyperthyroidism or alcohol abuse. Although uncommon causes for this arrhythmia have been described in recent years [1], [2], [3], the aetiology of this condition remains unknown. It has been suggested that a disorder of autonomic tone may play an important role in this type of arrhythmia [4], and an “atrial arrhythmia syndrome of vagal origin” characterized by recurrent paroxysmal atrial arrhythmia, present in middle aged males with no underlying structural heart disease and triggered by vagal overactivity, has been described [5].

In a recent study, we reported sport practice to be more frequent in LAF patients than in the general population of the same age in northern Spain [6]. This association has also been observed in a study of Finnish orienteers [7]. Although LAF could be considered a benign condition [8], it is generally associated with symptoms [8], causes a significant impairment of quality of life [9], and has been associated with increased mortality [10], [11].

The aim of this population-based study was to confirm and determine the magnitude of the association between sport practice and LAF in men.

Section snippets

Design

The study was an age-matched prospective population-based case–control study.

Subjects

A total of 70 patients younger than 65 years of age with LAF were identified from the hospital records of 1160 consecutive patients seen at the outpatient arrhythmia clinic between October 1997 and March 1999. Of these, 51 were men.

LAF was defined as atrial fibrillation in the absence of structural heart disease or other identifiable cause of arrhythmia, such as hyperthyroidism or alcohol abuse. Patients with mild

Results

The characteristics of the 109 control men and the 51 male patients included in this study are presented in Table 1. No statistically significant differences were observed in age, smoking status, and hypertension prevalence between cases and controls. No significant differences were observed in the proportion of subjects reporting current or former sport practice, the years of practice, the years since cessation, and the number of lifetime hours of sport practice among groups. The only

Discussion

In this study we have documented that current and prolonged sport practice was associated with a three times higher prevalence of LAF, and with five times higher prevalence of vagal LAF.

These results are similar to those observed by Karjalainen et al. [7], who reported a higher risk of LAF in vigorously exercising middle aged men (orienteers) than in the general Finnish population. In that study the prevalence of LAF was 5.3% and 0.9% in the orienteers and the control population, respectively.

Conclusion

In men, the combination of accumulated lifetime and current sport practice is associated with a three fold higher risk of LAF. Future studies are warranted to confirm these results and investigate the mechanisms underlying this association.

Acknowledgements

Dr A. Sambola and Dr E. García-Morán were supported by a grant from the Foundation for Biomedical Research, Hospital Clinic, Barcelona. This work was partially supported by the Spanish Network of Cardiovascular Research Centers (RECAVA, FIS-C03/01).

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