Purpose: Although left atrial (LA) enlargement is a recognized component of athlete's heart, dynamic cavity changes occurring during the training period remain to be elucidated. We aimed to investigate the adaptive changes of LA reservoir, conduit, and active volumes in elite athletes vs. controls and their response to different training loads.
Methods: LA maximum, pre-P, and minimum volumes were assessed in 26 top-level athletes and 23 controls. In athletes, LA volumes were measured at pre-, mid-, end-training, and post-detraining time points using conventional 2D echocardiography.
Results: Athletes had larger maximum (27.5 ± 3.2 vs. 20.3 ± 5.8 mL/m(2), p = 0.001), pre-P (11.5 ± 0.9 vs. 9.8 ± 2.2 mL/m(2), p = 0.001), and minimum (6.6 ± 0.9 vs. 5.0 ± 1.2 mL/m(2), p < 0.001) LA indexed volumes, compared with controls. Total and passive emptying volume indices were also larger in athletes compared with controls (18.7 ± 3.1 vs. 15.3 ± 4.9 mL/m(2), p < 0.05 and 13.8 ± 2.9 vs. 10.5 ± 4.6 mL/m(2), p < 0.05, respectively), while active emptying volume was similar (p = 0.74). During training, LA maximum (p < 0.0001), pre-P (p < 0.0001), minimum (p < 0.0001), total (p < 0.005), and passive (p < 0.05) emptying volume indices progressively increased, while active emptying volume (p = 0.10) and E/e' ratio (p = 0.32) remained unchanged. After detraining, LA volume measurements were not different from pre-training ones. End-training left ventricular mass index was the only independent predictor of the respective maximum LA volume (β = 0.74, p < 0.005).
Conclusions: Top-level athletes exhibit a dynamic morphological and functional LA remodeling, induced by training, with an increase in reservoir and conduit volumes, but stable active volume. LA remodeling is closely associated with left ventricular adaptation to exercise and both completely regress after detraining.