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.