Three-dimensional echocardiographic analysis of right atrial volume in normal and abnormal hearts: comparison of biplane and multiplane methods

Background: Although right atrial size has clinical and prognostic importance, few data exist regarding the optimal three‐dimensional echocardiography (3DE) method for assessing right atrial volume (RAV). While measuring RAV in multiple planes may improve the accuracy, it also increases analysis time. The purpose of this study was to determine the minimum number of planes required for optimal assessment of RAV, using eight‐plane 3DE measurements as a reference standard. Methods: 3DE was performed in 70 subjects (35 normal and 35 abnormal). 3DE RAV was obtained from three methods by tracing right atrial endocardial borders at ventricular end‐systole in two orthogonal planes (two‐plane), four equiangular planes (four‐plane), and eight equiangular planes (eight‐plane) in each subject. The time required for analysis was recorded for each method. Results: Based on eight‐plane RAV, mean RAV was 41±13 mL in the normal group, and 82±35 mL in the abnormal group. The average time for two‐plane, four‐plane, and eight‐plane analysis was 69 ± 29, 118 ± 29, and 203 ± 37 s, respectively (P < 0.001 for comparisons between all groups). Four‐plane approach had close agreement with eight‐plane (2.6% underestimation for total group), while two‐plane measurement underestimated RAV by an average of 19% for the total group, compared to eight‐plane. Conclusion: Four‐plane measurement of RAV shows good agreement with eight‐plane measurement, while reducing the time required for analysis. Compared to eight‐plane analysis, biplane measurement of RAV can result in underestimation of RAV, particularly in abnormal subjects with right atrial enlargement and remodeling. (Echocardiography 2012;29:608‐613)