Abstract 15564: Complex Remodeling of Left Atrial Appendage Predisposes to Thrombus Formation in Patients with Nonvalvular Atrial Fibrillation
Background: Left atrial appendage (LAA) thrombus formation depends on multiple factors. However, whether LAA morphological characteristics are related to LAA thrombus formation has not been identified. The aim of this study was to determine relationship between LAA structure and LAA thrombus formation using 3-dimensional (3D) transesophageal echocardiography (TEE) in patients with atrial fibrillation (AF).
Methods: In 250 nonvalvular AF patients (197 males, 60±11years), TEE were performed to assess LAA thrombus. Details of LAA structure were assessed by 3D TEE; LAA orifice area, depth, volume, and number of LAA lobes were measured on reconstructed 3D imaging. Severity of LAA spontaneous echo contrast (SEC) and LAA flow velocities were assessed to determine LAA flow stasis and LAA function. Type of AF, CHADS (2) score, and echocardiography measures were compared to determine variables to predict LAA thrombus.
Results: In patients with LAA thrombus (n=19), significantly larger LAA orifice area, longer depth, larger volume, and increased number of lobes were observed compared to those without LAA thrombus. In addition, higher prevalence of persistent AF, higher CHADS (2) score, higher grade of SEC, larger LA volume, and lower LAA filling and emptying flow velocity were identified compared to those without LAA thrombus. In a multivariate logistic regression analysis, LAA filling flow velocity (RR=0.92, 95% CI; 0.87–0.99, P=0.04) and the number of LAA lobes (RR=4.17, 95% CI;1.56–11.0, P=0.002) were identified as independent predictors of LAA thrombus. In patients with persistent AF (n=136), the number of LAA lobes only was an independent predictor (RR=4.31, 95% CI; 1.47–12.7, P=0.007).
Conclusion: Increased number of LAA lobe was the strong predictor of LAA thrombus formation on the basis of LAA dilatation. The complex structural change of LAA in patients with AF may be malignant remodeling that predisposes to thrombus formation in combination with LAA flow stasis.
- © 2010 by American Heart Association, Inc.