Left Atrial Strain Measured by Two-Dimensional Speckle Tracking Represents a New Tool to Evaluate Left Atrial Function

Background: Left atrial (LA) strain (ε{lunate}) and ε{lunate} rate (SR) analysis by two-dimensional speckle tracking can represent a new tool to evaluate LA function. To assess its potential value, the authors addressed whether LA ε{lunate} and SR measured in normal subjects correlates with other Doppler echocardiographic parameters that evaluate LA function and left ventricular function. Methods: Sixty-four healthy subjects were studied. LA ε{lunate} and SR were calculated with the reference point set at the P wave, which enabled the recognition of peak negative ε{lunate} (ε{lunate}_{neg peak}), peak positive ε{lunate} (ε{lunate}_{pos peak}), and the sum of those values, total LA ε{lunate} (ε{lunate}_tot), corresponding to LA contractile, conduit, and reservoir function, respectively. Similarly, peak negative SR (LA SR_{late neg peak}) during LA contraction, peak positive SR (LA SR_{pos peak}) at the beginning of LV systole, and peak negative SR (LA SR_{early neg peak}) at the beginning of LV diastole were identified. Results: Global LA ε{lunate}_{pos peak}, ε{lunate}_{neg peak}, and ε{lunate}_tot were 23.2 ± 6.7%, -14.6 ± 3.5%, and 37.9 ± 7.6%, respectively. Global LA SR_{pos peak}, SR_{early neg peak}, and SR_{late neg peak} were 2.0 ± 0.6 s^-1, -2.0 ± 0.6 s^-1, and -2.3 ± 0.5 s^-1, respectively. The above-described variables derived from analysis of global LA ε{lunate} and LA SR correlated significantly with Doppler echocardiographic indexes that evaluated the same phase of the cardiac cycle or the same component of the LA function, including indexes derived from mitral inflow, pulmonary vein velocities, tissue Doppler, and LA volumes. Global LA ε{lunate}_{pos peak}, LA ε{lunate}_tot, and LA SR_{early neg peak} also correlated significantly with age or body mass index. Global LA SR_{late neg peak} also correlated significantly with age. Conclusions: LA ε{lunate} analysis is a new tool that can be used to evaluate LA function. Further studies are warranted to determine the utility of LA ε{lunate} in disease states.