Assessing the left atrial appendage thrombus using 3D transesophageal echocardiography and pulse wave doppler
Authors: Djemmal B , Amrouche A , Salem M.A , Djermane D , Benkhedda S 
Published: October 2021

Abstract

Background/Introduction
In some patients, detecting and visualizing left atrial appendage (LAA) thrombus (especially at fundus level) seems to be challenging. Thus looking for indirect signs such as morphology, size and function may be of use.

Purpose
Finding echocardiographic signs suggesting presence of LAA thrombus using 3D TEE & pulse wave doppler.

Methods
We collected data via transesophageal echocardiography (TEE) from different set of patients with diseased heart (valvular especially mitral stenosis, congenital, pre-cardiac conversion for atrial fibrillation). And that by using EPIQ7 echo machine by Phillips. With each patient, we acquired pulse wave doppler determining the maximum (telesystolic) emptying velocity at mid LAA (MEV-LAA), and maximum long axis surface area of LAA (LAA-SA) using Xplan modality or multiplanar reconstruction from gated 3D acquisitions of LAA. Doing so we tried to assess the relationship between LAA thrombus and its morphology (2D/3D) using the 04 shapes classification (windsock, cauliflower, chicken wing, cactus), measuring LAA-SA considering a cutoff of 6cm2 or above a dilated LAA. A MEV-LAA considered diminished if less than 25cm/s. Finally we calculated the ratio of LAA-SA/MEV-LAA.

Results
We assessed a group of 55 patients. LAA thrombus was visualized in 10 of them. The predominant morphology was windsock 50.9% then equally chicken wing and cauliflower 14.5%, cactus 11%. Thrombus occurred in major part with cauliflower type with 50% of all patients with the same shape. LAA was dilated in 25 patients in whom 7 had LAA thrombus (Se: 70% Sp: 60% PPV: 22%). LAA maximum emptying velocity was reduced in 18 patients in whom 10 had LAA thrombus (Se: 100% Sp: 82.2% PPV: 36%). We found that 7 patients with a ratio LAA-SA/MEV-LAA &lt;1.7 had LAA thrombus (Se: 70% Sp: 97.8% PPV: 47%).
Cauliflower morphology has the highest occurrence of thrombus as demonstrated in the literature. LAA-SA is the least reliable criteria associated with LAA thrombus. MEV-LAA is has the most sensible value of the three measurements. The ratio LAA-SA/MEV-LAA seems to have the highest specificity and positive predictive value in terms of association with thrombus (in cauliflower type this ratio seems to be less specific). Some limitations of this study was the limited number of patients assessed, no comparison in terms of sex (LAA size is different in men and women according to literature), sinus rhythm versus atrial fibrillation (LAA maximum emptying velocity), no correlation with CT-scan of LAA concerning dimensions and thrombus.

Conclusion
3D transesophageal echocardiography and pulse wave doppler study of the LAA seems to be associated with thrombus formation especially indirect signs and indexed values (ratio LAA-SA/MEV-LAA), that tends to push the diagnostic power of TEE. Promptly this will lead to more investigations on a large scale number of patients in different sub-type groups.

Funding Acknowledgement
Type of funding sources: Public hospital(s). Main funding source(s): Mustapha Pacha University Hospital Center, department of Cardiology A2 3D TEE of LAA and Mitral prosthesisXplan on LAA, cauliflower type