Left atrial appendage orifice dimensions in Japanese atrial fibrillation population measured by multiplane transesophageal echocardiography

Background Successful implantation of the WATCHMAN device requires an accurate understanding of left atrial appendage (LAA) anatomy and orifice dimensions. Racial differences are observed in LAA size when comparing Asians with non-Asians. Methods A total of 170 patients (123 male, 67.4 ± 9.2 years) with paroxysmal or persistent atrial fibrillation (AF) underwent transesophageal echocardiography before catheter ablation or cardioversion (September 2018 to September 2019). As per the recommendations of the WATCHMAN device, the maximal LAA ostial diameters were measured at multiplane angles of 0°, 45°, 90°, and 135°. Results The majority of patients (121/170, 71%) had an LAA orifice size within 17–25 mm. Fifteen (8.8%) patients had undersized (< 17 mm) and eight (0.5%) had oversized (> 31 mm) LAA. One patient in this population had no LAA. LAA size was significantly larger in patients with persistent AF than in those with paroxysmal AF (23.3 ± 4.2 mm vs. 20.0 ± 3.0 mm, p < 0.001) and in male patients than in female patients (22.4 ± 4.2 vs. 20.9 ± 3.7 mm, p = 0.03). LAA orifice dimension was significantly correlated with CHADS 2 score, the left atrial volume (LAV), E / e ′, and the left ventricular ejection fraction. Persistent AF, body mass index, and LAV were independently associated with LAA orifice dimension in multivariate analysis. Conclusion This study demonstrated the distribution of LAA orifice dimension in the Japanese AF patients. This finding should be used as a reference to understand the racial characteristics of LAA size for the WATCHMAN procedure.