Introduction:
Exercise is beneficial for a wide range of diseases and associated with lower cardiovascular morbidity and mortality.1, 2 When it comes to atrial fibrillation (AF), however, the effect of exercise is ambiguous. While exercise of low and moderate intensity and duration lowers the risk of AF, prolonged endurance exercise is associated with an increased risk of AF in men.3-6 To accommodate the increased demands of exercise, endurance athletes experience structural, functional, and electrical cardiac remodeling referred to as the “athlete’s heart”.7 While cardiac remodeling is a physiological response to exercise, the athlete’s heart shares several common features with pathologically remodeled hearts, and to separate physiological from pathological atrial remodeling in athletes is a challenging task.8, 9 Current knowledge indicates that functional measures obtained by speckle-tracking echocardiography could be more helpful than mere size when trying to differentiate physiological from pathological atrial remodeling in veteran endurance athletes. However, data is sparse and somewhat conflicting.9-12 Studies assessing atrial function in athletes with AF have focused on left atrial (LA) strain values.10-13 Speckle-tracking echocardiography can also be used to measure the timing of atrial contraction. LA mechanical dispersion (LA MD), defined by the standard deviation of time-to-peak strain (SD-TPS), is a marker of electromechanical atrial function. It is reported to be a novel predictor of AF in the general population, linked to the recurrence of AF after catheter ablation, and associated with stroke among AF patients.14-17 Watanabe et al. found an association between increased LA MD and low voltage zones recognized by voltage mapping in paroxysmal AF patients indicating regional fibrosis in the LA wall.18 There has also been a report of increased atrial fibrosis assessed by magnetic resonance imaging (MRI) in a group of healthy veteran endurance athletes, linking long-term endurance exercise to increased atrial fibrosis.19 Still, the impact of long-term endurance exercise on LA MD, the interplay between AF, endurance exercise, aging, and LA MD, and the ability of LA MD to identify athletes with paroxysmal AF in sinus rhythm have yet to be investigated.
The main aim of this study was to investigate LA MD in veteran endurance athletes with and without AF and to evaluate the ability of LA MD to identify veteran athletes with paroxysmal AF when in sinus rhythm.