Left atrial longitudinal strain correlates better than its emptying fraction with left ventricular impairment in hypertrophic cardiomyopathy

Purpose. Three-dimensional echocardiography (3DE) is more accurate and reproducible than conventional echocardiography in assessing left atrial (LA) volumes and function. Impairment of myocardial longitudinal strain has been recently correlated with fibrosis burden at both left ventricular (LV) and LA level. Our aim was to assess the relationship of LA longitudinal strain with LA function indices provided by 3DE, as well as their respective relationship with LV function in HCM. Methods: 32 pts with HCM (51+13 yrs, 20 men), 2D and 3D LA data sets were analyzed using GE EchoPac BT12 and TomTec 4D LA analysis software. 2 pts have been excluded due to poor quality LA acquisitions. 2D LA longitudinal strain at the end of reservoir phase (PALS) and LA strain at atrial contraction (PACS) obtained from 4- and 2-chamber views were averaged. 3D LA volumes (maximal, LAV max; minimal, LAVmin; and before atrial contraction, LAVpreA), total emptying fraction (total EF) and active emptying fraction (active EF) were semi-automatically computed using 3D echocardiography. LV mechanical function was assessed in terms of 2D longitudinal strain (2DLS - absolute values) and E/e’average. Results: Impairment of LA longitudinal performance was correlated with LA volumes across all phases: LAVmax (r=-0.73 for PALS and PACS), LAV preA (r=-0.76 for PALS and -0.73 for PACS), LAVmin (r=-0.70 for PALS and -0.71 for PACS) (p,0.0001 for all). Modest correlations were identified for LA strain parameters with 3D LA total EF and active EF (r=0.57 and 0.56 for PALS; r=0.54 and 0.50 for PACS). LA strain parameters, as opposed to total EF and active EF, were correlated with LV 2DLS (r=0.74 for PALS and 0.54 for PACS) and inversely with E/e’average (r=-0.38 for PALS and -0.42 for PACS). 3D LA phasic volumes were also correlated with LV 2DLS (r=-0.43 for LAVmax and r=-0.36 for LAVpreA, p,0.05) and filling pressures (r=-0.43, p=0.02 for all LA phasic volumes). Conclusion: InHCMpatients, there is only a modest relationship between LA longitudinal deformation and LA function parameters assessed by 3DE. LA 2D longitudinal strain and LA 3D volumes could be more useful clinical indicators of myocardial impairment inHCM than 3D LA emptying fraction.