Left atrial size: a structural expression of abnormal left ventricular segmental relaxation evaluated by strain echocardiography

Abstract

Aims: Left atrial (LA) enlargement is related to left ventricular (LV) remodelling and diastolic dysfunction (DD), reflecting cardiac target organ damage. The aim of this study was to investigate the relation of one-dimensional (1D) and volume derived indexes of LA enlargement with abnormal segmental relaxation in hypertensive patients.

Methods and results: We evaluated 90 hypertensive patients and 50 non-hypertensive volunteers with normal ejection fraction (EF). Global DD was evaluated based on conventional indexes (E/A, deceleration time, LV isovolumic relaxation time), and segmental early and late diastolic strain rates (SR) were recorded from 18 LV segments. The number of segments with abnormal relaxation (SR(E)/SR(A) < 1.1) was represented as segmental DD. LA size was evaluated based on 1D left atrial dimension (LAD) and left atrial volume (LAV), and indexed by body surface area (BSA) and height. The hypertensive patients had higher segmental DD (9.5 +/- 4.2 vs. 5.2 +/- 3.2, P < 0.05) and appeared to have higher 1D and volume-derived indexes of LA size compared to the controls. Individuals with global DD had more deteriorated segmental relaxation and higher LA size compared with those without global DD. When participants were separated according to normal, mildly dilated, and moderately to severely dilated LA size, there was progressive deterioration of segmental DD, mean Ea, and filling pressures, along with the progression of LA enlargement. Volume-derived indexes, LAV/BSA, LAV/height, and LAV, appeared to have better correlations with segmental DD, as well as with linearly changed parameters of DD (Mean Ea, E/Ea), LV remodelling (LVMI, relative wall thickness), age, and systolic blood pressure (SBP), compared to the respective 1D-based (LAD) LA indexes. LAV/BSA was proved to be an independent predictor of segmental DD (beta: 0.23, R(2): 0.48), along with LVMI, SBP and age, irrespective of gender.

Conclusion: LA size constitutes a morphological expression of abnormal segmental relaxation, with volume-derived indexes of LA enlargement, exhibiting higher correlation with segmental DD compared to the respective 1D indexes, and LAV/BSA to be an independent predictor of segmental DD in hypertensive heart disease.