Transesophageal Echocardiographic Assessment of Right Atrial Appendage Anatomy and Function: Comparison with the Left Atrial Appendage and Implications for Local Thrombus Formation

Abstract

We sought to define right atrial appendage (RAA) anatomic and functional parameters in a consecutive series of participants and to compare these measures with left atrial appendage (LAA) indices among patients with in sinus rhythm and atrial fibrillation (AF). With AF, both atria are fibrillating, yet the vast majority of thrombi are located within the LAA. Transesophageal echocardiography provides anatomic and functional information regarding both the LAA and the RAA. In a consecutive series of 92 patients (48 men; age 61 +/- 17 years) referred for transesophageal echocardiography, RAA and LAA anatomy (width, length, area) and ejection velocity were measured at two orientations (RAA, 90 and 135 degrees; LAA, 0 and 90 degrees). RAA anatomic measures were similar for both imaging planes, whereas LAA area was larger at 90 degrees. There was a modest correlation between RAA and LAA anatomic measures (area: r = 0.58, P = .001). RAA neck width was substantially greater than LAA neck width (P < .0001) whereas appendage area was similar (P = not significant) and RAA neck width/area was greater than LAA neck width/area (P < .0001). AF was associated with approximately 50% decline in ejection velocity for both the LAA and the RAA with an increase in LAA area (P = .006 vs sinus), but similar anatomic remodeling was not found for the RAA (P = not significant vs sinus). In this consecutive series of patients undergoing transesophageal echocardiography, RAA anatomic and functional parameters were found to be independent of imaging plane, with anatomic measures demonstrating a correlation with LAA measures. Although AF is associated with depressed RAA and LAA ejection velocities, anatomic RAA remodeling appears to be absent. The larger RAA width and lack of anatomic remodeling may partially explain the substantially lower prevalence of RAA thrombus found among patients with AF.