BACKGROUND:Although transesophageal echocardiography is the definitive test for the detection of left atrial (LA) appendage thrombus, transthoracic echocardiography has yet to prove useful for the determination of increased risk for LA appendage thrombus formation. The authors hypothesized that higher LA volume and/or lower left ventricular ejection fraction (LVEF) might prove valuable as markers of increased risk for LA appendage thrombus formation and tested this hypothesis in a consecutive retrospective series of patients with atrial fibrillation undergoing both transthoracic and transesophageal echocardiography. METHODS:Three hundred thirty-four consecutive patients with atrial fibrillation undergoing transesophageal echocardiography for the detection of LA appendage thrombus were studied. Anticoagulation status, CHADS(2) scores, and echocardiographic parameters were catalogued. The relationship between the presence of LA appendage thrombus and covariates was analyzed using binary logistic regression. RESULTS:LA appendage thrombus was detected in 52 patients (15.6%). A higher CHADS(2) score (odds ratio, 1.45; P < .004), increased LA volume index (odds ratio, 1.02; P = .018), and lower LVEF (odds ratio, 1.02; P = .05) were significant predictors of LA appendage thrombus formation. LA appendage thrombus was not seen in patients with CHADS(2) scores ≤ 1, LVEFs > 55%, and a LA volume indexes < 28 mL/m(2). A ratio of LVEF to LA volume index ≤ 1.5 produced 100% sensitivity for the presence of LA appendage thrombus. CONCLUSIONS:The presence of LA appendage thrombus is related to both clinical and echocardiographic variables. Although no single echocardiographic variable discriminated between the presence and absence of LA thrombus, a normal LVEF and normal LA volume index were associated with the absence of LA appendage thrombus formation. For patients with atrial fibrillation with CHADS(2) scores ≤ 1, normal left ventricular systolic function and normal LA volume in combination may be a useful measure for the identification of patients at low risk for LA appendage thrombus formation.

Left atrial (LA) volume is an important prognostic factor in cardiovascular disease. Multidetector computed tomography (MDCT) is an emerging cardiac imaging modality; however, its accuracy in measuring the LA volume has not been well studied. The aim of our study was to determine the accuracy of MDCT in quantifying the LA volume. A total of 48 patients underwent MDCT and 2-dimensional (2D) echocardiography (2DE) on the same day. The area length and Simpson's methods were used to obtain the 2D echocardiographic LA volume. The LA volume assessment by MDCT was obtained using the modified Simpson's method. Four artificial phantoms were created, and their true volume was assessed by an independent observer using both imaging modalities. The correlation between the LA volume by MDCT and 2DE was significant (r = 0.68). The mean 2D echocardiographic LA volume was lower than the LA volume obtained with MDCT (2DE 79 +/- 37 vs MDCT 103 +/- 32, p <0.05). In the phantom experiment, the volume obtained using MDCT and 2DE correlated significantly with the true volume (r = 0.97, p <0.05 vs r = 0.96, p <0.05, respectively). However, the mean 2D echocardiographic phantom volume was 16% lower than the true volume (2DE, Simpson's method 53 +/- 24 vs the true volume 61 +/- 24, p <0.05). The mean volume calculated using MDCT did not differ from the true volume (MDCT 60 +/- 21 vs true volume 61 +/- 24, p = NS). 2DE appeared to systematically underestimate the LA volume compared to phantom and cardiac MDCT, suggesting that different normal cutoff values should be used for each modality. In conclusion, LA volume quantification using MDCT is an accurate and feasible method. (C) 2010 Elsevier Inc. All rights reserved. (Am J Cardiol 2010;106:104-109)