Evaluation of the Left Atrial Appendage with Real-Time Three-Dimensional Transesophageal Echocardiography: Implications For Catheter-Based Left Atrial Appendage Closure Nucifora et al: RT3DTEE Imaging of LAA

Background Precise knowledge of left atrial appendage (LAA) orifice size is crucial for correct sizing of LAA closure devices. Aim of the present study was to determine the performance of real-time three-dimensional transesophageal echocardiography (RT3DTEE) for LAA orifice size assessment, compared to twodimensional transesophageal echocardiography (2DTEE), and to investigate the impact of atrial fibrillation (AF) on LAA orifice size. Methods and Results 137 patients (38 controls, 31 with paroxysmal AF, 38 with persistent AF and 30 with permanent AF) underwent 2DTEE and RT3DTEE. Both techniques were used to measure LAA orifice area. Clinically-indicated 64-slice computed tomography (CT) was used as reference technique in 46 patients. 2DTEE underestimated LAA orifice area, compared to RT3DTEE (1.99±0.94 cm vs. 3.05±1.27 cm; p<0.001). RT3DTEE showed higher correlation with CT for the assessment of LAA orifice area, compared to 2DTEE (r=0.92, 95%CI 0.85-0.95, vs. r=0.72, 95%CI 0.54-0.83, respectively). At Bland–Altman analysis, RT3DTEE and 2DTEE underestimated LAA orifice area, compared to CT. However, RT3DTEE showed smaller bias (0.07 cm vs. 0.72 cm) and narrower limits of agreement (-0.71 to 0.85 cm vs. -0.58 to 2.02 cm) with CT, compared to 2DTEE. Among AF patients, a progressive increase in RT3DTEE-derived LAA orifice area was observed with increasing frequency of AF (p<0.001). At multivariate analysis, AF and left atrial volume index (p<0.001 for both) were independently associated with RT3DTEEderived LAA orifice area. Conclusions RT3DTEE is more accurate than 2DTEE for the assessment of LAA orifice size. A progressive increase in LAA orifice area is observed with increasing frequency of AF.