Normal Values of Echocardiographic Left Atrioventricular Coupling Index and Left Atrial Stiffness Index Reflecting Left Ventricular Diastolic Function: A Multicenter Study.

Background: The left atrioventricular coupling index (LACI) and left atrial stiffness index (LASI) have recently demonstrated significant correlations with left ventricular (LV) diastolic function. However, the absence of reference values limits their widespread use. This study aimed to establish normal reference ranges for LACI and LASI.

Methods: A total of 1,648 healthy participants from 55 centers were enrolled. The LACI was defined as the ratio of left atrial (LA) minimum volume to LV end-diastolic volume. The LASI was calculated as the ratio of the average E/e' ratio to LA reservoir strain.

Results: Both LACI and LASI increased with age in both sexes. The LACI was higher in women than in men (P < .001), whereas no significant sex difference was observed for LASI (P = .868). Age, sex, LV global longitudinal strain (GLS), and LA reservoir strain independently predicted LACI. Age, body mass index, LV GLS, and LA volume index were independently associated with LASI. Elevated LACI and LASI were observed in participants with high-normal blood pressure, overweight status, and indeterminate LV diastolic function.

Conclusions: Sex- and age-stratified reference values for LACI and LASI were established. Left ventricular GLS, LA reservoir strain, and LA volume index should be considered when interpreting these parameters. Hypertension, obesity, and LV diastolic dysfunction may significantly affect LACI and LASI, suggesting their potential utility in identifying early cardiac dysfunction.