Early Echocardiographic Predictors for Atrial Fibrillation Propensity: The Left Atrium Oracle

Abstract

Atrial fibrillation (AF) results from structural and electrical remodeling of the atria, primarily of the left atrium (LA); therefore, LA changes, both anatomical and functional are recognized as proarrhythmic markers with a powerful prognostic value. Being widely available and noninvasive, echocardiography is used to monitor LA form and function in clinical practice. Early functional (electrical) remodeling of the LA precedes anatomical alterations. Impaired LA functions and reduced atrial compliance due to atrial fibrosis may be evaluated using novel echocardiographic techniques, such as tissue Doppler analysis and speckle tracking. Functional evaluation of the LA conveys prognostic information about the risk of AF, as the severity of the impairment is an independent predictor of new-onset AF and AF recurrence. However, specific parameters are still investigated for incorporation into algorithms to predict future AF occurrence. The aim of the review is to summarize echocardiographic parameters, their predicting value and applicability in practice.

Keywords: atrial fibrillation; left atrium dimensions left atrium function; left atrium remodeling; left atrium reverse remodeling.

Fig. 1.

Measurement of the LA diameter (end-systole, inner edge to inner edge) in the parasternal long-axis view by bidimensional echocardiography.

Fig. 2.

Bidimensional echocardiography – 4 chambers view, maximum left atrium dedicated view.

Fig. 3.

Left atrium tridimensional volume and function using 3D-E speckle tracking with a dedicated software.

Fig. 4.

PW Doppler evaluation of the transmitral diastolic flow. E wave – early diastolic filling of the LA; A wave – late diastolic filling determined by atrial contraction.

Fig. 5.

Pulmonary venous flow using PW Doppler echocardiography S systolic flow, D diastolic flow, Ar atrial reversal.

Fig. 6.

PW Doppler evaluation of the LAA flow showing low velocities in a patient with atrial fibrillation.

Fig. 7.

PW Tissue Doppler evaluation at the level of the septal mitral annulus for evaluation of E’ and A’.

Fig. 8.

Assessment of LA function by speckle tracking echo using the R-R interval – peak systolic LA strain (arrow). Four-chamber view depicting the region of interest (ROI, in the left). The curves represent the mean global LA longitudinal strains. The reference point was set at the onset of the R-wave. The total global strain is positive at the opening of the mitral valve (red arrow). Global strain at atrial contraction is also positive (white arrow). The total global strain is a sum of the negative global strain at atrial contraction (red arrow – at mitral valve closure) and the positive global strain (white arrow – at mitral valve opening).

Fig. 9.

Strain evaluation of the left atrium using the P-P interval. Four-chamber view depicting the region of interest (ROI, in the left). The curves represent the mean global LA longitudinal strains. The reference point was set at the onset of the P-wave. The total global strain is a sum of the negative global strain at atrial contraction (red arrow – at mitral valve closure) and the positive global strain (white arrow – at mitral valve opening).