ABSTRACT
Introduction: This study was carried out to (i) provide the methodology for determining left atrial (LA) volume, emptying fraction and ejection force (LAEF), from real-time 3-dimensional echocardiography (RT3DE), and (ii) evaluate the effects of age and gender on LA volume and LAEF in a wide age range of healthy participants.
Materials and Methods: RT3DE was performed in 102 healthy participants (age range, 20 to 80 years). From full-volume data sets, LA endocardial borders were automatically traced and LA volumes were determined. LAEF was calculated as 1/3×mitral annular area × (blood density) × (peak velocity of A wave)2 according to Newton’s law of motion and hydrodynamics; wherein the mitral annular area (MVA) is traced using RT3DE and A is the peak Doppler-derived blood velocity at atrial systole with the sample volume placed at the mitral annulus level. Results: ANOVA analysis revealed that LA volume indices were significantly correlated with age (r = 0.366, P <0.0001 for maximal volume index and r = 0.288, P <0.005 for minimal volume index). LAEF was also significantly positively correlated with age (r = 0.49, P <0.0001). The LA emptying fraction was maintained across ages. LA volume indices and LAEF did not differ significantly with gender. Conclusion: Our data can be used as normal reference values for LA volumes and LAEF. We have demonstrated that age is positively related to LA volume indices and LAEF, which suggests that age-dependent cut-off values should be considered in those with heart disease.The left atrium (LA) plays the primary role in the filling of the left ventricle (LV). A number of studies have demonstrated that LA enlargement (i.e. volume increase) is a negative prognostic factor for survival in patients with a variety of cardiovascular disorders, including stroke, congestive heart failure and myocardial infarction. In the absence of mitral valve disease, an enlarged LA is also a marker of chronic elevated LV filling pressures. LA ejection force (LAEF) is a measure of atrial systolic function and plays an important role in LV diastolic filling. In a similar way to LA enlargement, LAEF also serves as an independent determinant of prognosis in patients with heart failure. Real-time 3-dimensional echocardiography (RT3DE) is a new non-invasive imaging technique that has been shown to be useful for assessing LA volumes due to its high feasibility rate of data acquisition and convenient semi-automated offline analysis. Unfortunately, the prior methodology for LAEF determination has proven to be inaccurate. Also, to our knowledge, there have been no published studies on the effect of age and gender on LA volume and LAEF as assessed by RT3DE in healthy participants. Therefore, our main aims were to (i) provide the methodology for determining LA volume, emptying fraction and ejection force using RT3DE, and (ii) determine the effects of age and gender on LA volumes and LAEF using RT3DE in healthy participants across a wide range of ages. Accordingly, the outcomes would establish reference standards for future studies regarding the assessment of LA volumes and contractile function in patients with atrial fibrillation or LV diastolic dysfunction.
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