Right and Left Atrial Dissimilarities in Normal Subjects Explored by Speckle Tracking Echocardiography

Atrial function is an important contributor of ventricular function and has a prognostic role in various cardiovascular diseases. We tested the hypothesis that right and left atrial (RA & LA) function may not be equal despite their accommodating identical cardiac output.

Two-dimensional (2D) speckle tracking echocardiography was acquired from the apical four-chamber view in 100 normal subjects. Both RA/LA subendocardial borders were traced to obtain atrial volumes, strain (ε) and strain rate (SR). Reservoir, conduit, and booster pump functions were evaluated. Consequently, εNeg (corresponding to pump function) and εPos (corresponding to conduit function) were gauged. The SR parameters (SRLateNeg, SRPos, and SREarlyNeg), corresponding respectively to atrial systole, inception of ventricular systole, and inception of ventricular diastole, were measured.

Mean age was 39 ± 15 years with 50 men (50%). Volumetric indices revealed that reservoir (Filling Volume = 35.1 ± 10.4 mL for LA vs. 27.47 ± 11.93 mL for RA, expansion index = 52.18 ± 16.89% for LA vs. 45.03 ± 16.49% for RA and diastolic emptying index = 52.85 ± 16.85 for LA vs. 45.62 ± 16.5 for RA, P < 0.001) and conduit (passive emptying (%) of total emptying = 34.49 ± 10.4 for LA vs. 26.82 ± 11.98 for RA and passive emptying index = 52.63 ± 16.86 for LA vs. 45.39 ± 16.5 for RA, P < 0.001) functions were significantly higher in the LA compared to the RA. Nevertheless, deformation indices demonstrated an opposite pattern (SRpos = 1.88 ± 0.74 for RA vs. 1.56 ± 0.54 for LA, P = 0.03 and εPos = 59.56 ± 30.63 for RA vs. 45.94 ± 16.67 for LA, P < 0.001). Reservoir, conduit, and booster pump functions showed no statistical significance among both genders.

Evaluation of global and regional RA/LA function by speckle tracking echocardiography is feasible. The current report provides insights regarding dissimilarities between both atria in healthy individuals. The significance of these findings and their potential application will warrant further work.