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Published on: February 8, 2022
Prevalence of left atrial appendage pseudothrombus filling defects in patients with atrial fibrillation undergoing
Farhood Saremi1, Stephanie Channual, Swaminatha V Gurudevan
1Department of Radiological Sciences, University of California Irvine, UCI Medical Center, Orange, CA 92868-3298, USA. fsaremi@uci.edu
Insights
Computed tomography angiography (CTA) can reveal filling defects in the left atrial appendage (LAA) of patients with atrial fibrillation (AF). These common defects are often pseudothrombi and not actual blood clots.
Area of Science:
- Cardiology
- Radiology
- Medical Imaging
Background:
- Computed tomography (CT) is a valuable noninvasive tool for detecting atrial thrombi.
- Blood stasis in the left atrial appendage (LAA) of patients with atrial fibrillation (AF) can lead to false-positive results.
- Distinguishing true thrombi from pseudothrombi is crucial for accurate diagnosis and treatment.
Purpose of the Study:
- To investigate the prevalence of LAA filling defects that mimic thrombus in patients with AF during coronary CT angiography (CTA).
- To compare the incidence of these defects in patients with AF versus healthy individuals.
- To assess the relationship between LAA volume, cardiac phase, and the presence of filling defects.
Main Methods:
- Retrospective analysis of coronary CTA scans from 7 patients with AF and 250 healthy individuals.
- Evaluation of LAA filling defects in patients with AF.
- Measurement of LAA volume at 10 different cardiac phases in patients with AF and 30 healthy controls.
- Comparison of LAA volumes and volume changes across cardiac phases between groups.
Main Results:
- Filling defects suggestive of thrombus were observed in 5 out of 7 patients with AF (71.4%) on CTA.
- Follow-up imaging confirmed the absence of thrombus in these patients.
- No LAA filling defects were detected in 250 patients without AF.
- Patients with AF exhibited significantly larger LAA volumes across all measured cardiac phases compared to healthy individuals.
- Patients with AF showed reduced dynamic changes in LAA volume throughout the cardiac cycle compared to controls.
Conclusions:
- Filling defects in the LAA of patients with AF undergoing coronary CTA are common and often represent pseudothrombi.
- These pseudothrombi should not be misdiagnosed as actual thrombi, necessitating careful interpretation of CTA findings.
- Understanding these imaging characteristics can improve diagnostic accuracy and guide appropriate clinical management in AF patients.
Background:
Previous reports have shown that computed tomography (CT) is a useful, noninvasive test for detecting atrial thrombi. However, blood stasis in the left atrial appendage (LAA) of patients with atrial fibrillation (AF) may be a common cause for false-positive results.
Objectives:
We retrospectively evaluated the prevalence of filling defects that may simulate thrombus in the LAA of patients with AF during routine coronary CT angiography (CTA).
Methods:
The LAA of 7 patients with AF was studied for the presence of filling defects and compared with 250 healthy persons. LAA volume in the patients with AF was measured at 10 different cardiac phases and compared with 30 healthy patients.
Results:
Of the 7 patients with AF studied with CTA, 5 were positive for LAA filling defects. Follow-up imaging studies, including transesophageal echocardiogram, contrast-enhanced magnetic resonance angiography, or delayed-CT, were negative for LAA thrombus. Of 250 patients without AF, CTA showed no evidence of LAA filling defects. Patients with AF had significantly larger LAA volumes at all cardiac phases measured compared with patients without AF (15.2 +/- 6.93 mL compared with 6.85 +/- 3.01 mL at atrial contraction [P = 0.0187], 17.4 +/- 7.76 mL compared with 9.46 +/- 3.43 mL at ventricular systole [P = 0.0351], and 14.5 +/- 5.87 mL compared with 8.48 +/- 3.10 mL at mid-diastole [P = 0.0341]). Compared with the healthy persons, the patients with AF showed reduced percentages of change in LAA volume when the atrial contraction phase was compared with other phases: 44.0% +/- 25.6% compared with 16.5% +/- 12.2% compared with ventricular systole (P = 0.0004) and 29.5% +/- 23.7% compared with -1.63% +/- 8.84% at mid-diastole (P < 0.0001).
Conclusions:
Pseudothrombus filling defects are common in the LAA of patients with AF undergoing coronary CTA and should not be mistaken for real thrombus.
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