Left Atrial Phasic Function Remodeling During Its Enlargement: a Two-dimensional Speckle-tracking Echocardiography Study

Background: Left atrial (LA) size is often used as a surrogate marker of LA function in clinical practice, with larger atria thought to represent a “dysfunctioning” atrium, since there is no accepted ‘gold’ standard to evaluate LA function. The exact relationship between LA size and phasic function, and whether LA dysfunction occur before LA enlargement (LAE) may be of clinical interest while have not been fully studied. Two-dimensional speckle-tracking echocardiography (2D STE) was showed a promising method in measuring LA physic deformation. Materials and methods: A community cohort of 715 subjects at cardiovascular disease high risk accepted comprehensive echocardiography. LA longitudinal phasic strain Sa (absolute peak strain during atrial contraction), Se (peak strain at early diastole) and Stot (total atrial strain =Sa+Se), representing contractile, conduit, and reservoir function respectively, were measured using off-line 2D STE software in apical 4 chamber view, and data were compared among groups at different LA size and between sub-groups in normal LA size with and without hypertension (HT). Results: With LAE (from normal size, mild, moderate to severe LAE), the Stot(21.74±5.97,20.75±4.99,20.49±5.27,17.75±4.71, respectively, ANOVA p=0.003) and Sa (11.84±3.92,11.00±3.29,10.11±2.57,8.55±2.88, respectively, ANOVA p<0.001) reduced while Se had no change. In normal sized LA subgroups, Stot (21.35±5.91 vs 23.01±6.02, p=0.008) and Se (9.51±4.41 vs 11.17±4.89, p<0.001) reduced in subjects with HT comparing with those without. Conclusion: LA phasic function remodeling occurs before LAE and continues with LAE, with reservoir, conduit and contractile function being affected unparalleled.