Atrial fibrillation in middle-aged athletes: Differences in relation to sex and participation in competitions

Abstract

This chapter reviews recently established relationship of atrial fibrillation (AF) with endurance sports activities in middle-aged athletes. We connect findings from various types of evidence in order to investigate this phenomenon since the pathophysiology of AF in middle-aged athletes is still unclear. In majority of studies where the higher risk of AF for athletes was observed, the subjects were participants at competitions, and there is no evidence of increased risks of AF with non-competing athletes. We also discuss sex differences, since all studies up to now demonstrated that long-term vigorous exercise increases the risk of AF only in men (while it decreases the risk in women). Sympathetic tone in women might be less elevated during endurance sports activities than in men, due to the less competitive character and evidence from several studies are presented. Stress and increased sympathetic tone in competition might be a cause of AF inducing the atrial inflammation leading to the autonomic imbalance and atrial fibrosis and as a consequence, to the atrial fibrillation. Evidence on much higher levels of cortisol in athletes as stress response to competition (when compared with levels in endurance training) is also reviewed. Long-lasting stress, induced by endurance sports activities and additionally elevated due to competitions and male competitive character, might cause the inflammation, and as consequences atrial fibrosis and atrial fibrillation. In some studies it is indicated that endurance sports activities (as a preparation for marathon race) induce inflammation. In contrary, in other studies it is indicated that exercise reduces oxidative stress and inflammation (as a consequence of aging) in middle-aged and older athletes. Consequently, the final effect is positive (reduction of inflammation) unless stress is induced by competition and in this case the total effect might be opposite (increase in inflammation) and atrial fibrillation.