Determinants of LA Strain: Independent Effects of LA Volume and LV Global Longitudinal Strain

Abstract

Background: Left atrial (LA) global longitudinal strain (GLS) by 2D echocardiography has demonstrated prognostic value. LA GLS has been linked to left ventricular (LV) function but the impact of altered LA volume has not been well studied. We sought to examine the relationship between LA GLS, LA volume and LV GLS. Method: Patients without previous cardiac disease referred for exercise stress echocardiography were prospectively recruited. All participants underwent comprehensive transthoracic echocardiography (TTE) prior to exercise stress echocardiogram. Only patients with no evidence of ischaemia on stress echocardiogram, normal LV ejection fraction (LVEF) and left ventricular mass indexed (LVMI) were included. Results: 260 patients (57% male, mean age 59 ± 14 yrs) with normal LVEF and LVMI were included. 182 (70%) patients had hypertension (HTN), 86 (33%) patients had diabetes mellitus (DM) and 81 (31%) patients had HTN and DM. On linear regression analysis, both LV GLS (p < 0.01) and indexed LA volume (LAVI) (p < 0.01) were independent determinants of LA GLS. For further evaluation, we examined LA GLS and LV GLS as tertiles based on tertiles of LAVI. At the lower tertiles of LAVI, a linear relationship was observed between LA GLS and LV GLS. At higher tertiles of LAVI, reduction in LA GLS relative to worsening LV GLS was non-linear and exponential. Conclusion: Out findings suggest that in the presence of normal LAVI, LA GLS had a linear relationship to LV GLS. LA remodelling reflected by larger LAVI had an incremental negative association with LA GLS independent of LV GLS.