P695 Is reference value of left atrial strain using 2D echocardiography really reliable?

Abstract

Abstract Funding Acknowledgements MT received research grant from GE Healthcare. Background Left atrial (LA) longitudinal strain (LALS) assessed by two-dimensional echocardiography (2DE) speckle tracking analysis is increasingly popular for the estimation of left ventricular diastolic dysfunction and the prediction of adverse outcome. Since standard apical 4-chamber and 2-chamber views often maximize the long-axis of the left ventricle, and the long axis of the left ventricle and that of the left atrium do not lie on the same 2D cutting plane, these views have a risk for the foreshortening of the left atrium. It may cause overestimation of LALS due to the reduction of initial perimeter of region of interest that is a denominator for the strain calculation. Purpose The aim of this study was to compare LALS values between 2DE and 3D echocardiography (3DE) in healthy subjects, and investigate whether 2DE speckle tracking analysis overestimates reference value of LALS. Methods LALS and LA longitudinal length were measured by both 2DE and 3DE in 105 healthy subjects (median age, 42 years; 59 men). For 2DE, LA longitudinal length from the mitral annulus to the roof of the left atrium were measured on apical 4-chamber and 2-chamber views at end-diastole and at end-systole, and the values were averaged. Apical 4-chamber and 2-chamber LALS was also measured using 2DE speckle tracking software (EchoPac PC, GE Healthcare) for calculating biplane LALS. 3DE LALS was measured using new 3DE LA strain software (4D Auto LAQ, GE Healthcare). 3DE determined LA longitudinal length at both end-diastole and end-systole was also measured using the same 3DE datasets. Results Mean values of biplane LALS was 39.6 ± 11.8%. 2DE LA longitudinal length at both end-diastole (r=-0.43) and end-systole (r=-0.54) was negatively correlated with biplane LALS. Multivariable regression analysis revealed that both end-diastolic and end-systolic LA longitudinal length had a significant negative association for biplane LALS after adjusting anthropometric and echocardiography image quality parameters. 3DE LALS analysis was not possible in 11 subjects due to the erroneous LA border determination (Feasibility: 90%). 3DE LALS (23.7 ± 7.6%) was significantly lower than biplane LALS (39.5 ± 12.0%, p < 0.001) with a weak correlation (r = 0.33) in 94 subjects who were possible in both analyses. Paired comparison of LA longitudinal length between 2DE and 3DE revealed that 2DE determined LA length at end-diastole (3.51 ± 0.72 cm vs. 4.85 ± 0.56 cm, p < 0.001) and at end-systole (4.63 ± 0.69 cm vs. 5.84 ± 0.54 cm, p < 0.001) was significantly shorter than that obtained from 3DE. Conclusions Our results highlighted that LA cavity visualizing on the standard apical 4-chamber and 2-chamber views are often longitudinally foreshortened, and this is a potential cause for the overestimation of LALS. 3DE may overcome this limitation.