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Updated: May 6, 2026
Echocardiographic Evaluation of Atrial Communications before Transcatheter Closure
Published on: February 8, 2022
Comparison of transesophageal echocardiography versus computed tomography for detection of left atrial appendage
Matthew J Budoff1, Adekunle Shittu1, Yalcin Hacioglu1
1Department of Internal Medicine, Los Angeles Biomedical Research Institute at Harbor UCLA Medical Center, Torrance, California.
Insights
Cardiac CT angiography effectively excludes left atrial appendage thrombus. Quantitative analysis of Hounsfield unit density and the LAA/aorta ratio improves detection accuracy for thrombus, aiding atrial fibrillation patient management.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Medical Diagnostics
Background:
- Patients with atrial fibrillation undergoing pulmonary vein isolation often require imaging to assess for left atrial appendage (LAA) thrombus.
- Transesophageal echocardiography (TEE) and cardiac computed tomographic angiography (CCTA) are commonly used, with CCTA previously showing high sensitivity and negative predictive value (NPV) for LAA thrombus.
Purpose of the Study:
- To determine the optimal Hounsfield unit (HU) density cutoff for LAA thrombus detection using CCTA.
- To establish the optimal LAA to ascending aorta (AA) HU density ratio for detecting LAA thrombus.
- To compare quantitative CCTA measurements against TEE in a multicenter population.
Main Methods:
- Eighty-four patients who underwent both CCTA and TEE were included.
- CCTA was used for qualitative (visual assessment) and quantitative (LAA HU density, LAA/AA HU ratio) evaluation of the LAA.
- Quantitative measurements used a 1-cm area of interest in the same axial plane, with results compared to TEE findings of thrombus or spontaneous echo contrast.
Main Results:
- Qualitative CCTA showed 100% sensitivity and 100% NPV for LAA thrombus detection compared to TEE, but only 77.9% specificity and 51.6% positive predictive value (PPV).
- The optimal LAA HU density cutoff for thrombus detection was 119 (sensitivity 88%, specificity 86%, PPV 56%, AUC 0.923).
- The optimal LAA/AA HU density ratio was 0.242 (sensitivity 87%, specificity 88%, PPV 64%, AUC 0.921); both quantitative methods improved specificity and PPV over qualitative assessment.
Conclusions:
- Multidetector computed tomography is a valuable tool for excluding LAA thrombus due to its high NPV.
- Quantitative CCTA measurements, specifically LAA HU density (cutoff 119) or LAA/AA HU ratio (cutoff 0.242), enhance the accuracy of positive thrombus detection.
- These quantitative techniques are particularly useful in scenarios without delayed scanning or when LAA thrombus is an incidental finding.
Abstract:
Patients with atrial fibrillation, who are referred for radiofrequency pulmonary vein antral isolation, frequently undergo transesophageal echocardiography (TEE) to detect and/or exclude left atrial or left atrial appendage (LAA) thrombus and cardiac computed tomographic angiography (CCTA) to define and/or evaluate left atrial and pulmonary venous anatomy. Previous studies have reported CCTA to have high sensitivity and negative predictive value (NPV) for detecting thrombus in the LAA. Previous studies determining an optimal LAA/ascending aorta (AA) Hounsfield unit (HU) density ratio for detection of LAA thrombus have been small, with limited numbers of thrombi. We thus sought to determine both the optimal cutoff for LAA HU density and LAA/AA HU density ratio in detecting LAA thrombus compared with TEE in a multicenter population. We included 84 patients who had undergone CCTA and TEE. LAA was evaluated by 64-row CCTA qualitatively (visual filling defect) and quantitatively (measurement of LAA HU density and LAA/AA HU density ratio), using a 1-cm area of interest in the same axial plane. Results were compared with TEE visualization of thrombus or spontaneous echo contrast. Qualitative identification of thrombus in LAA by CCTA compared with TEE detection of thrombus had a sensitivity of 100%, a specificity of 77.9%, a positive predictive value (PPV) of 51.6%, an NPV of 100%, and a total accuracy of 82.1%. The optimal LAA HU density cutoff for thrombus detection was 119 with a sensitivity of 88%, a specificity of 86%, PPV 56%, and an area under the curve of 0.923 (p = 0.0004). The optimal LAA/aorta HU ratio was 0.242 with a sensitivity of 87%, a specificity of 88%, a PPV of 64%, and an area under the curve of 0.921 (p = 0.0011). There is no significant difference (p = 0.72) between both areas under the curve, and both measurements improved the specificity and PPV compared with qualitative measures. Multidetector computed tomography is an imaging technique that can exclude LAA thrombus with very high NPV. Quantitative measurement of LAA HU density (cutoff 119) or LAA/aorta HU density ratio (cutoff 0.242) improves accuracy of positively detecting LAA thrombus. This technique is especially useful when delayed scanning is not performed and LAA is found incidentally after the patient scanning is complete.
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