Abstract 17795: Left Atrial Appendage Volume Reflects Severity of Mitral Regargitation: A Three-Dimensional Transesophageal Echocardiography Study

Abstract

Background: Left atrial (LA) size is well known to reflect volume overload condition such as mitral regurgitation (MR). However, the effects to left atrial appendage (LAA) have not been well defined. LAA structure has multilobed complicated three-dimensional structures. Recent development of real-time 3-dimensional transesophageal echocardiography (RT3D-TEE) has enabled us to examine morphology and determine absolute volumes of LAA without geometrical assumptions. We investigated the relationship between MR severity and LAA volume. Methods: Seventy-four patients with MR who underwent RT3D-TEE were studied. All measurements were performed off-line software. Maximal LAA orifice area, depth and volume, and the number of LAA lobes were assessed (Figure). We also measured LAA emptying flow velocity (LAAev) as the average of 3 consecutive cardiac cycles in patients in normal sinus rhythm and 5 consecutive cardiac cycles in patients with atrial fibrillation. MR grade was evaluated by vena contracta width (VCW). In 58 patients, we also determined the maximal LA volume by the Simpson method from apical views by 2-dimensional transthoracic echocardiography. Pulsed Doppler E, tissue Doppler E' and E/E' were also measured. Results: Mean LAA orifice area was 5.0±3.8 cm 2 , LAA volume was 11±10 ml, LA volume was 116±57ml, and LAAev was 41±23 cm/sec. Patients with moderate to severe MR had larger LAA orifice area, LAA volume, and LA volume than patients with mild MR (Table). In contrast, there were no relationship between MR severity, the number of LAA lobes and LAAev. 3D derived LAA volume was correlated with VCW significantly (r=0.51, p<0.01). Conclusion: LAA volume was associated with MR severity.