Detailed Insights into the Relationship Between Three-Dimensional Speckle-Tracking Echocardiography-Derived Systolic Left Atrial Global Strains and Left Ventricular Volumes in Healthy Adults from the MAGYAR-Healthy Study

<b>Background and Objectives:</b> The complex relationship between three-dimensional (3D) speckle-tracking echocardiography (3DSTE)-derived left ventricular (LV) and left atrial (LA) volumes and functional properties has been demonstrated in recent studies. A better understanding of LV volumetric dependence on systolic peak LA (reservoir) strains in healthy circumstances could complete this knowledge. Therefore, 3DSTE was used for the simultaneous evaluation of these parameters in healthy adults, aiming to examine their complex relationship. <b>Materials and Methods:</b> The present study consisted of 165 healthy individuals with a mean age of 33.1 ± 12.3 years and 90 men. A complete two-dimensional echocardiography with Doppler with 3DSTE was performed in all the cases. <b>Results:</b> The peak LA global radial (GRS), longitudinal (GLS), and 3D (G3DS) strains were increased in the subjects with a mean LV end-diastolic volume (EDV) as compared to those cases with a lower-than-mean LV-EDV. In the cases with a higher-than-mean LV-EDV, no further increase in these peak global LA strains could be detected. The peak LA global circumferential and area strains showed a tendentious (non-significant) increase with an increasing LV-EDV. The peak LA global strains showed similar non-significant associations with the LV end-systolic volume (except the peak LA-G3DS, which proved to be significant). <b>Conclusions:</b> In healthy adults, the 3DSTE-derived peak LA-GRS and LA-G3DS are increased with a larger LV-EDV up to a point, beyond which a further increase cannot be seen, suggesting a working Frank-Starling mechanism in this context similar to that for LA volumes. Similar associations are present for the peak LA-GLS as well.