Prognostic Significance of Left Atrial Appendage "Sludge'' in Patients with Atrial Fibrillation: A New Transesophageal Echocardiographic Thromboembolic Risk Factor

Background: When stratifying thromboembolic risk to patients with atrial fibrillation (AF), left atrial appendage (LAA) thrombus is currently the only echocardiographic index that absolutely contraindicates cardioversion. The aim of this study was to identify the predictors of LAA "sludge'' and its impact on subsequent thromboembolism and survival in patients with AF. Methods: A total of 340 patients (mean age, 66 +/- 12 years; 75% men) who underwent transesophageal echocardiography to exclude LAA thrombus before electrical cardioversion or radiofrequency pulmonary vein isolation) for AF were retrospectively studied. LAA sludge was defined as a dynamic, viscid, layered echodensity without a discrete mass, visualized throughout the cardiac cycle. Follow-up was obtained after a mean of 6.7 +/- 3.7 years, and patients were analyzed according to LAA thrombus (n = 62 [18%]), sludge (n = 47 [14%]), or spontaneous echocardiographic contrast (n = 84 [25%]). Patients without these transesophageal echocardiographic characteristics served as controls (n = 147 [43%]). Results: LAA sludge was independently predicted by enlarged left atrial area (odds ratio, 4.54; 95% confidence interval [CI], 2.38-8.67; P < .001), reduced LAA emptying velocity (odds ratio, 12.7; 95% CI, 6.11-26.44; P < .001), and reduced left ventricular ejection fraction (odds ratio, 2.11; 95% CI, 1.03-4.32; P < .001). Thromboembolic event and all-cause mortality rates in patients with sludge were 23% and 57%, respectively. Multiple logistic regression analyses identified the presence of LAA sludge to be independently associated with thromboembolic complications (adjusted hazard ratio, 3.43; 95% CI, 1.42-8.28; P = .006) and all-cause mortality (adjusted hazard ratio, 2.02; 95% CI, 1.22-3.36; P = .007). Conclusion: Sludge within the LAA is independently associated with subsequent thromboembolic events and all-cause mortality in patients with AF.