Unveiling a hide side of the athlete's heart: a CMR focus on the left atrium.

Abstract Background cardiac magnetic resonance (CMR) is the gold standard to evaluate cardiac chambers’ dimensions and function, but data on left atrium (LA) dimensions and function among elite athletes are lacking. Objective to describe LA size and function among a cohort of elite athletes and evaluate eventual differences based on sports discipline and gender. Methods We enrolled 120 Olympic athletes with un-remarkable cardiovascular pre-participation screening tests (mean age 25±5 years, 50% males, 25% skill, 25% power, 25% mixed, 25% endurance). All the athletes underwent CMR without contrast administration. LA dimensions, in terms of absolute and indexed area and volume, were computed using 4- and 2-chamber steady state precession cine-sequences. LA ejection fraction (LAEF) and LA coupling index (LACI index, as the ratio between LA and LV end-diastolic volumes) were calculated. Cine-images were also used to analyse atrial deformation with a dedicated offline software to measure LA global longitudinal strain. LA dimensions and function were compared between males and females and athletes of different sports categories based on European classification. Results Among the entire cohort, endurance athletes showed the greatest remodelling in terms of LA and LV dimensions (Table). There were no significant differences in LAEF and LV-EF between athletes of different sport categories (p=0.121 and p=0.679). A trend in increasing LA volumes and decreasing LA strain consistent with a growing cardiovascular demand was observed, but the only statistically significant difference was between skill athletes and all the other groups for LA volumes (p<0.001), while there were no significant differences in LA strain (p=0.170). LACI did not differ between athletes of different sports categories (p=0.170). Female athletes showed higher LAEF and LA strain than males (respectively 55±5 vs 52±6% p=0.012 and 35±7 vs 32±7%, p=0.009) while LACI did not differ based on gender (19±5% for both females and males, p=0.385). Conclusion Among our cohort of Olympics, LA remodelling was observed in all athletes, being less evident in skill group, as for the LV. Thus, the ratio between LA and LV did not differ between sport categories. LAEF and LA strain were not significantly different between athletes of different sports categories although LA strain was slightly lower in endurance. Female athletes showed higher LAEF and LA strain than males, while LACI was not different based on gender.