Regional heterogeneity in left atrial stiffness impacts passive deformation in a cohort of patient-specific models

TL;DR

This study used patient-specific models to analyze how regional variations in left atrial stiffness influence its passive deformation, revealing that stiffness is a key factor in atrial biomechanics, especially in atrial fibrillation.

Contribution

The paper introduces a method to fit regional myocardial stiffness in patient-specific LA models and demonstrates its significance in LA deformation, advancing understanding of atrial biomechanics in AF.

Findings

Regional myocardial stiffness varies across the LA.

Stiffness significantly influences regional LA deformation.

Anatomical features are less impactful than stiffness.

Abstract

The deformation of the left atrium (LA), or its biomechanical function, is closely linked to the health of this cardiac chamber. In atrial fibrillation (AF), atrial biomechanics are significantly altered but the underlying cause of this change is not always clear. Patient-specific models of the LA that replicate patient atrial motion can allow us to understand how factors such as atrial anatomy, myocardial stiffness and physiological constraints are linked to atrial biomechanics. We created patient-specific LA models from CT images. We fitted regional model stiffness to peak CT-derived deformation during the LA reservoir phase ($\pm0.90$ mm) and used the CT deformation transients through the reservoir and conduit phase for model validation (deformation transients fell within $\pm0.38$ mm per unit time of targets). We found that myocardial stiffness varies regionally across the LA. The regional stiffness values were significant factors contributing to regional physiological LA deformation ($p=0.023$) while features of LA anatomy, including regional wall thickness and adipose volume, were less important. These findings provide insight into the underlying causes of altered LA biomechanics in AF.