Transesophageal echocardiographyfor detection of left atrial appendage thrombi: Is it good enough?
Credits:Mazda Biria1, Thomas Rosamond MD1, Dhanunjaya Lakkireddy1, Louis Wetzel, MD21Department of Cardiovascular Disease (Mid-America Cardiology), 2Department of Radiology, The University of Kansas Hospital
Disclosure : There areno relevant conflicts of interests for any of the authors involving the currentstudy topic;
Corresponding Author: Thomas L. Rosamond, M.D., Clinical Assistant Professor of Medicine, Co-Director of Cardiovascular Computed Tomography/Magnetic Resonance Imaging, Department of Cardiovascular Disease (Mid-America Cardiology), The University of Kansas Hospital, Mail Stop 4023, 3901 Rainbow Boulevard, Kansas City, Kansas 66160-7200. Tel: 913-588-9600. Fax: 913-588-9770. E-mail: firstname.lastname@example.org
Abbreviations: TEE: TransesophagealEchocardiogram, CTA: Computed Tomographic Angiography.
Key Words: TEE, atrial fibrillation, left atrial appendage, thrombosis, CT angiogram, and multi-slice cardiac computed tomographic angiography.
doi : 10.4022/jafib.v1i1.418
Transesophageal echocardiography (TEE) has beenconsidered the gold standard for visualization of left atrial appendage thrombiprior to electrocardioversion in patients with atrial fibrillation1. We report two cases in which 64-slice computed tomographic angiography (CTA)demonstrated prominent left atrial appendage thrombi in spite of a negativetransesophageal echocardiogram.
A 65-year old gentleman with a 10 year historyof paroxysmal atrial fibrillation and left ventricular dysfunction was beingprepared for 64-slice cardiac CTA prior to planned pulmonary venous isolation. In the interim however, he presented with symptomatic persistent atrialfibrillation and was submitted for elective cardioversion after transesophagealechocardiography was performed and failed to demonstrate a left atrialappendage thrombus (Figure 1). He was successfully cardioverted with a sub-therapeuticINR. A subsequent 64-slice CT angiogram was performed the same day as part ofpreparation for radiofrequency ablation. Sixty-four slice CTA demonstrated alarge thrombus in the left atrial appendage (Movie 1).
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Figure 1 : Transesophagealechocardiogram negative for presence of thrombus.
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Video 1 : CTAngiogram from Case 1 showing presence of thrombus.
A 66-year old gentleman with a history of persistentatrial fibrillation for six months with therapeutic INRs was admitted to thehospital for direct current electrical cardioversion. A previous cardioversionhad failed to maintain sinus rhythm. Transesophageal echocardiogram wasperformed prior to cardioversion and did not show evidence for left atrialappendage thrombus (Figure 2). The patient was successfully cardioverted tonormal sinus rhythm without complications. The INR remained therapeuticthroughout the hospital stay. A 64-slice CTA was obtained the next day inorder to identify the pulmonary venous anatomy in preparation for pulmonaryvenous isolation but demonstrated the presence of a large mobile thrombus inthe left atrial appendage (Movie 2).
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Figure 2 : Transesophagealechocardiogram in Case 2 was also negative for presence of thrombus.
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Video 2 : CTAngiogram from Case 2 showing presence of thrombus.
Transesophageal echocardiography has recognizedlimitations in the visualization of the left atrial appendage due to chambersize and shape variability2. Nevertheless, studiesemploying transesophageal echocardiography have been said to show 100%sensitivity for the detection of left atrial thrombi3. The chanceof thrombus formation in atria is high after cardioversion due to myocardial stunningand it has been considered as the cause of CVA/TIA after cardioversion. The twocases presented in this report however, demonstrate the limitation of transesophagealechocardiography to detect even large mobile thrombi in the left atrialappendage. Subtherapeutic INR in the first case may explain presence of thrombiin the left atrium at the time of CTA. However, in the presence of therapeuticanticoagulation with warfarin in the second case, left atrial appendage thrombuswas unrecognized by TEE. None of these cases had a known history of thrombosisthat suggests hypercoagualable state. Studies have shown limitations of CTA in diagnosis of left atrial appendage due to high interobserver variability4, inability of distinguishing between thrombus and slow blood flow in the appendage5, and low sensitivity in comparison to TEE5,6. Left atrial appendage sometimes is difficult to visualize in its entirety by TEE as was in the two mentioned cases. The tip of the LAA if very long, curved and with greater branching could pose a problem in identifying clots with TEE.
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