The Influence of Left Atrial Wall Thickness and Curvature on Wall Strain in Patient-Specific Atrium Models

Abstract

Fibrosis is thought to be a major contributor to atrial fibrillation. Strain is a potential signal for fibrosis in the left atrium (LA). Local strain can be impacted by local anatomy. This study investigated correlation of local strain magnitude with local anatomy described by curvature and wall thickness. We created $3D$ motion models of the LA from retrospective gated computed tomography images from 8 patients. We calculated wall thickness and endocardial curvature across the LA at end-diastole $(ED)$ then calculated LA endocardial area strain throughout the cardiac cycle, using the $ED$ frame as the reference. The average Pearson's correlation of end-systolic strain with inverse wall thickness and curvature was - $0.076\pm0.095$ and 0.01 $7\pm0.81$ respectively. The correlations between inverse wall thickness, curvature and the first four principal components of strain showed no greater dependence of strain on wall thickness or curvature. The LA was divided into 18 regions and correlation was calculated regionally. Regionally, the range of correlation of strain at ES with thickness and curvature was $(-0.58-0.43)$ and $(-0.49-0.47)$ respectively. Neither wall thickness nor curvature appear to strongly influence strain. This is consistent with either boundary forces acting on the atria or variations in regional stiffness impacting regional differences in strain.