This study was designed to determine the ability and reliability of 3-dimensional (3D) transesophageal echocardiography (TEE) to assess the geometry and size of the left atrial appendage (LAA). Three-dimensional TEE may allow more accurate assessment of, and provide additional information on, LAA morphology compared to 2-dimensional TEE. Validation studies for LAA morphology data derived from 3D TEE were performed using 10 isolated porcine LAA specimens. Of 107 enrolled patients, 55 patients were in sinus rhythm (normal sinus rhythm), in whom 3D transesophageal echocardiographic images were obtained from full-volume mode imaging, and in 52 patients with atrial fibrillation, zoom-mode imaging was used. LAA orifice area, depth, and volume and the number of LAA lobes were assessed on reconstructed 3D imaging. Left atrial volume was calculated using 2-dimensional echocardiographic imaging. In experimental studies, excellent correlations (r >0.90, p <0.001) between the measurements by full-volume or zoom-mode imaging and reference data were observed in all parameters. The mean LAA orifice long diameter was 29.7 +/- 7.4 mm, the mean short diameter was 20.6 +/- 5.9 mm, the mean orifice area was 5.1 +/- 2.5 cm(2), the mean LAA depth was 38.5 +/- 8.2 mm, and the mean volume was 9.2 +/- 5.6 ml. The most frequent number of LAA lobes was 2 (n = 52), followed by 3 (n = 28), 1 (n = 18), and 4 (n = 3). Left atrial volume was weakly correlated with LAA orifice long diameter (r = 0.33, p = 0.001), short diameter (r = 0.40, p <0.001), area (r = 0.39, p <0.001), LAA depth (r = 0.21, p = 0.03), and volume (r = 0.36, p = 0.001). In conclusion, 3D TEE is a reliable modality to evaluate LAA geometry and provides detailed information to quantify varied LAA characteristics.
