Assessment Of Left Atrial Volume And Function In Patients With Atrial Fibrillation By Real-time Three Dimensional Echocardiography

Objective: Atrial fibrillation(AF)is one of the most common arrhythmias and its morbidity and mortality are also on the rise.Left atrial volume has been recognized as an important predictor of cardiovascular disease morbidity and mortality.Magnetic resonance imaging(MRI)is considered as the gold standard for evaluating the left atrial volume.The left atrial volume measured by multislice spiral computed tomography(MSCT)has a good consistency and repeatability compared with the MRI results.Echocardiography is the most commonly used method for clinical evaluation of left atrial volume.Compared with MRI and MSCT,echocardiography significantly underestimated left atrial volume,but the influence of left atrial enlargement on the accuracy of left atrial volume measured by real-time three-dimensional echocardiography(Rt-3DE)is still unclear.In this study,the left atrial volume measured by 256-slice spiral CT was used as a reference to evaluate the accuracy of real-time three dimensional echocardiography in measuring left atrial volume and function.Method: There were 108 cases of atrial fibrillation by transthoracic echocardiography(TTE)and computed tomography angiography(CTA).The three-dimensional volume of the left atrial was obtained by echocardiography and MSCT reconstruction with the corresponding software.The left atrial maximal volume(LAVmax)and left atrial minimal volume(LAVmin)were measured,and left atrial ejection fraction(LAEF)was calculated.Measurement of left atrial volume was standardized by body surface area.Left atrial size was divided into normal range group(Group I),mild abnormal group(Group II),moderate abnormal group(Group III)and severe abnormal group(Group IV)according to echocardiography guidelines.SPSS was used for statistical analysis.The continuous variable was expressed as mean ± standard deviation.The paired t-test was used to compare the difference between the two methods.Pearson correlation coefficient was used to analyze the correlation between the two methods.The Bland-Altman method was used to assess the bias and consistency between the two methods.Linear regression was combined with one-way anova to analyze the difference of underestimation among groups.P-value < 0.05 was considered statistically significant.Results:1.Left atrial maximal volumeThere was positive correlation between Rt-3DE and MSCT measurements in the total sample(r=0.81,P<0.001).Compared with MSCT,Rt-3DE significantly underestimated the left atrial maximum volume by approximately 56.81ml(approximately 44%).Linear regression analysis showed that there was positive correlation between the volume underestimated value and the extent of left atrial enlargement(r=0.78,P< 0.05),and negative correlation between the volume underestimated percentage and the extent of left atrial enlargement(r=-0.26,P<0.05).With varying degree of enlargement of the left atrium,the underestimationed volume would increase,while the percentage of underestimated volume would decrease.2.Left atrial minimum volumeThere was positive correlation between Rt-3DE and MSCT measurement in the total sample(r=0.73,P<0.001).Compared with MSCT,Rt-3DE significantly underestimated the left atrial minimum volume by approximately 59.12ml(approximately 56%).Linear regression analysis showed that there was positive correlation between the volume underestimated value and the extent of left atrial enlargement(r=0.73,P<0.05),and negative correlation between the volume underestimated percentage and the extent of left atrial enlargement(r=-0.50,P<0.05).With varying degree of enlargement of the left atrium,the underestimationed volume would increase,while the percentage of underestimated volume would decrease.3.Left atrial ejection fractionThere was positive correlation between Rt-3DE and MSCT measurements in total samples(r=0.25,P<0.001).Compared with MSCT,Rt-3DE significantly overestimated the left atrial ejection fraction by approximately 56%.Conclusions:1.There is high correlation between left atrial volume measuremented by Rt-3DE and left atrial volume measuremented by MSCT.Real-time threedimensional echocardiography systematically underestimate the volume of the left atrium and overestimate the ejection fraction of the left atrium.2.In patients with atrial fibrillation,as varying degree of enlargement of the left atrium,the underestimationed volume by real-time three-dimensional echocardiography will increase,while the percentage of underestimated volume will decrease.