Left Atrial Reservoir Strain Across Atrial Fibrillation Phenotypes: A Case-Control Echocardiographic Study

Background: Atrial fibrillation (AF) is associated with progressive structural, electrical, and mechanical remodeling of the left atrium. Left atrial reservoir strain (LASr) and the PA-TDI interval have emerged as potential echocardiographic markers of atrial dysfunction and fibrosis. However, their relationships across different AF phenotypes and their incremental associations with conventional echocardiographic parameters require further evaluation. Objective: To compare LASr among individuals with no AF (controls), paroxysmal AF, and persistent AF, and to determine whether differences remain after adjustment for clinical covariates, left atrial (LA) size, and derived LA emptying fraction. Secondary objectives were to assess the relationship between LASr and PA-TDI and explore the discriminatory performance of LASr using receiver operating characteristic (ROC) analysis. Methods: This study evaluated LASr across three groups: controls, patients with paroxysmal AF, and patients with persistent AF. Comparative analyses were performed to examine differences in LASr among the groups, followed by adjusted analyses incorporating available clinical covariates and conventional echocardiographic measures of atrial remodeling. The association between LASr and PA-TDI was examined in participants with measurable PA-TDI values. Exploratory ROC analyses were conducted to assess the ability of LASr to distinguish between AF phenotypes and controls. Conclusion: This study provides a comparative assessment of LASr across different AF phenotypes and examines its incremental association with clinical and conventional echocardiographic measures of atrial remodeling. The findings are intended to clarify the relationship between atrial mechanical dysfunction and AF progression while providing an exploratory evaluation of LASr and PA-TDI as echocardiographic markers. The results should be interpreted as replication and incremental-association evidence rather than as the discovery of a novel diagnostic marker.