Left Atrial Strain: State of the Art and Clinical Implications

Abstract

The assessment of left atrial strain (LAS) has emerged as an essential component in the evaluation of cardiac function, especially in pathologies such as heart failure and atrial fibrillation. This narrative review aims to outline the available methods for assessing LAS with a major emphasis on speckle-tracking echocardiography techniques. Other imaging modalities, including cardiac magnetic resonance and cardiac computed tomography, also provide important information on LA dynamics but have disadvantages with respect to cost and availability. The current narrative review underlines basic concepts such as the accurate assessment of LAS and discusses the clinical relevance of LAS by pointing out its significant diagnostic and prognostic role in several cardiovascular conditions. The aim of this article is to discuss the current integration of LAS into clinical practice with a view to further improving patient management and treatment strategies.

Keywords: cardiovascular diseases; left atrial strain; speckle-tracking echocardiography.

Figure 1

Left atrial strain. The figure shows the different phases of LAS. In the apical four-chamber, begin tracing at the endocardial border of the mitral annulus, follow the LA endocardial border, extending across the pulmonary veins, and/or the orifices of the LA appendage, up to the opposite mitral annulus side. Note, the left atrium is in the far field and, therefore, has reduced image resolution, making it hard to detect speckles. Therefore, we primarily perform contour detection between the blood (black) and the wall (white), followed by calculating length changes. ROI width of 3 mm is recommended, though adjustments should be made to avoid including the pericardium.

Figure 2

Zero baseline, here defined as the end of diastole. Reservoir—end-diastole to peak (positive valve—LA getting bigger), so LV reservoir function represents LA relaxation and compliance, modulated by LV systolic function through the descent of the LV base. Conduit = value from the peak to the pre-contraction phase (negative value); LA conduit function is reliant on LV diastolic function, including both suction force dependent on LV relaxation and LV chamber stiffness. Contraction = pre-contraction point to baseline (negative value) LA booster function is based on intrinsic LA contractility and LV end-diastolic compliance and pressure.