Left atrial strain defines functional and structural remodeling in patients with persistent atrial fibrillation

Background: Left atrial (LA) strain is an echocardiographic method to detect atrial dysfunction as a process of structural and functional remodeling of the atria. In patients with persistent atrial fibrillation (AF), functional changes and an enlargement of the LA due to structural remodeling has been described. The aim of our study was 1) the echocardiographic assessment of LA function using LA strain and 2) to investigate the correlation between LA strain and left atrial size index (LAVI) using 3D reconstruction of the LA from multi-detector computed tomography (CT).

Methods: This study includes patients with persistent AF who underwent LA catheter ablation without prior treatment. All subjects underwent measurement of reservoir (LASr), conduit (LAScd) and contraction (LASct) LA strain using two-dimensional speckle tracking echocardiography (2D-STE) and cardiac CT. A 3D reconstruction of the LA from the CT was done using EnSite Verismo (Abbott, USA). The LA volume obtained at the end-systole included LA appendage reconstruction and excluded the pulmonary veins. LAVI was calculated by dividing LA volume by body surface area.

Results: The study included 36 patients (mean age 69 yrs [49 to 80 yrs], 27 male, mean LV-EF 56% [40 to 78%]).
We found the following LA strain measurement: mean LASr 21% [6 to 52%], mean LAScd -12% [-32 to -0,25%] and mean LASct -9% [-32 to -1%]. Mean LAVI: 82 ml/m² [38 to 127 ml/m²].
 
There is a statistically significant negative correlation between LASr (p = 0.002, r = -0.503) and a statistically positive correlation between LASct (p = 0.003, r = 0.482) compared to the LA volume, whereas there is no statistically significant correlation between LAScd and the LA volume (p = 0.088, r = 0.288).
 
Discussion: LA strain in patients with persistent AF as an expression of functional remodeling is reduced compared to normal values in literature. Correlation of LA strain and LAVI are statistically significant for LASr as well as LASct. The correlation between LAScd and LAVI did not reach statistical significance but shows a trend towards a positive correlation. Whether early treatment of AF could prevent further fibrotic remodeling with reducing LA volume and improving LA strain needs further research.