Associations between left atrial indices and cardiorespiratory and muscular fitness among physically active military personnel.

Abstract

Background: Left atrial (LA) size and function are linked to exercise intolerance in heart failure, while associations between LA parameters and exercise performance remain unclear in athletes.

Objectives: This study aimed to identify correlations between echocardiographic LA size, pressure, stiffness, and composite indices, and various exercise performance indicators.

Methods: Echocardiographic parameters were obtained from 181 physically active military personnel receiving regular training and tests for a 3-km run and 2 min of push-ups and sit-ups. The top 16% of runners were compared sex-specifically, with the remaining 84% as controls to identify LA discriminators for running capacity. LA composite indices were defined as the LA volume index (LAVI) divided by the stiffness index (LASI) or pressure index (mitral E/e'). Spearman correlations were used to identify LA correlates with exercise performance. Generalized linear regressions were used to identify LA predictors of exercise performance with adjustments for potential covariates.

Results: The top 16% of runners vs. controls had a lower LASI based on LA volume changes (LASI_v, 0.196 vs. 0.245, p = 0.013) and higher LAVI-to-LASI_v (12.30 vs. 8.08, p = 0.001) and LAVI-to-(mitral E/e') (4.37 vs. 3.76, p = 0.038) ratios. The LAVI-to-LASI_v ratio was the most highly correlated shared LA parameter for running (|rho| = 0.403), push-up (rho = 0.335), and sit-up (rho = 0.352) performance. The LAVI-to-mitral E/e' ratio was the most highly correlated, independent, and unique LA parameter for running (|rho| = 0.457) performance.

Conclusions: The LAVI-to-LASI_v ratio, comprising LA size and stiffness information, was the best correlate across exercise types, while the LAVI-to-mitral E/e' ratio, comprising LA size and pressure information, was the best correlate of an endurance exercise, i.e., 3-km running performance.