LAUSR

Type of funding sources: Foundation. Main funding source(s): A Ph.D. grant from the DAM Foundation and a grant from the Raagholt foundation. Prolonged endurance exercise is associated with an increased risk of atrial fibrillation (AF) in men. Increased left atrial (LA) size is associated with AF in the general population. LA dilation in athletes is viewed mainly as a physiological response to exercise, and functional atrial parameters may help distinguish pathological from physiological atrial remodeling in this group. LA mechanical dispersion (LA MD) is a novel marker of LA mechanical dyssynchrony. It is yet to be evaluated whether LA MD could be a marker of pathological remodeling in veteran athletes. To describe LA MD measured by speckle tracking echocardiography in male veteran athletes who had regularly participated in the 54 kilometer cross-country (XC) ski race Birkebeinerrennet in Norway with and without AF, and men with and without AF from a background population. In total, 295 men, veteran XC skiers with (n=57) and without (n=88) paroxysmal AF, and men from a non-athletic population with paroxysmal AF (n=62) and without AF (n=88) were examined with echocardiography while in sinus rhythm. LA MD was defined as the standard deviation of time to peak strain (SD-TPS) including all accepted atrial segments, and stated both in milliseconds, and corrected by the cycle length ((SD-TPS(ms)/Cycle length(ms))x100)). The average of three consecutive loops was computed. A two-way between-groups analysis of variance was performed to explore the main effects of AF status, athletic status, and the interaction between AF status and athletic status in LA echocardiographic parameters. XC skiers (mean age 70.9±5.7 years) reported an average of 40-50 years of regular endurance exercise and had completed an average of 17 annual Birkebeiner races. LA volumes were associated with both AF and athletic status. LA MD in milliseconds was associated with AF, but not associated with athletic status. LA MD was associated with paroxysmal AF both in veteran endurance athletes and non-athletes, and less affected by athletic status than atrial volumes. This implies that LA MD could be a useful marker when trying to distinguish physiological from pathological atrial remodeling in endurance athletes.