Aims: The aim of this study is to determine the incidence of lone atrial fibrillation (LAF) in males according to sport practice and to identify possible clinical markers related to LAF among marathon runners.
Methods and results: A retrospective cohort study was designed. A group of marathon runners (n = 252) and a population-based sample of sedentary men (n = 305) recruited in 1990-92 and 1994-96, respectively, were contacted in 2002-03 and invited to attend an outpatient clinic to identify suggestive symptoms of having experienced an arrhythmia requiring medical attention. In those with suggestive symptoms of atrial fibrillation, medical records were reviewed. Finally, LAF was diagnosed on the basis of the presence of atrial fibrillation in an electrocardiographic recording. In the group of marathon runners, an echocardiogram was performed at inclusion and at the end of the study. The annual incidence rate of LAF among marathon runners and sedentary men was 0.43/100 and 0.11/100, respectively. Endurance sport practice was associated with a higher risk of incident LAF in the multivariate age- and blood pressure-adjusted Cox regression models (hazard ratio = 8.80; 95% confidence interval: 1.26-61.29). In the group of marathon runners, left atrial inferosuperior diameter and left atrial volume were both associated with a higher risk of incident LAF.
Conclusion: Long-term endurance sport practice is associated with a higher risk of symptomatic LAF in men. This risk is associated with a larger left atrial inferosuperior diameter and volume in physically active subjects.