Introduction Vigorous endurance exercise promotes atrial fibrillation (AF), the most common cardiac arrhythmia in athletes.1 2 Previous studies have reported a prevalence of AF of between 13% and 29% in middle-aged and older male competitive endurance athletes with prolonged exposure to endurance exercise.3–5 Although under-represented in most prior studies, female athletes seem to have a lower prevalence of AF compared with males.6 7 The pathophysiology of AF in athletes is only partly...