Left Atrial Longitudinal Strain as a Tool for Detecting Left Atrial Appendage Spontaneous Echo Contrast in Atrial Fibrillation

Abstract

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, affecting approximately 2% of the population with substantial thromboembolic risk. The left atrial appendage (LAA) serves as the primary site of thrombus formation in non-valvular AF, accounting for up to 90% of cardiac emboli. Spontaneous echo contrast (SEC), detected by transesophageal echocardiography (TEE), represents blood stasis and serves as a validated marker of thrombogenic risk. However, TEE's semi-invasive nature limits its routine use. Left atrial longitudinal strain (LALS), measured non-invasively via speckle-tracking echocardiography, quantifies atrial myocardial deformation and reflects mechanical function. Recent evidence demonstrates strong inverse correlations between reduced LALS and LAASEC severity. Studies show that LALS cut-off values of 8-12% predict dense SEC with sensitivities and specificities exceeding 80-85%, providing incremental value beyond CHA₂DS₂-VASc scores and conventional echocardiographic parameters. This review synthesizes current evidence examining the relationship between LALS parameters and LAASEC in AF patients, explores underlying pathophysiological mechanisms, and discusses clinical applications for non-invasive thromboembolic risk stratification.