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Left atrial appendage thrombus is associated with a higher fractal dimension in patients with atrial fibrillation
Mengyuan Jing1, Huaze Xi1, Jianying Li2
1Department of Radiology, Lanzhou University Second Hospital, Lanzhou, China; Second Clinical School, Lanzhou University, Lanzhou, China; Key Laboratory of Medical Imaging of Gansu Province, Lanzhou, China; Gansu International Scientific and Technological Cooperation Base of Medical Imaging Artificial Intelligence, Lanzhou, China.
Insights
Higher left atrial appendage (LAA) fractal dimension (FD) indicates increased anatomical complexity and a greater risk of LAA thrombosis in atrial fibrillation (AF) patients. This imaging metric aids in predicting clot formation.
Area of Science:
- Cardiology
- Medical Imaging
- Biomedical Engineering
Background:
- Atrial fibrillation (AF) poses a significant risk for thromboembolic events, often originating from the left atrial appendage (LAA).
- Accurate assessment of LAA morphology and thrombotic risk is crucial for effective patient management.
- Traditional risk scores may not fully capture the anatomical complexities contributing to thrombus formation.
Purpose of the Study:
- To evaluate the anatomical complexity of the LAA using fractal dimension (FD) derived from cardiac computed tomography angiography (CTA).
- To investigate the association between LAA FD and the presence of LAA thrombosis in patients with AF.
- To compare the diagnostic performance of LAA FD against the CHA₂DS₂-VaSc score for predicting LAA thrombus.
Main Methods:
- Retrospective analysis of AF patients who underwent cardiac CTA and transesophageal echocardiography (TEE).
- Calculation of LAA FD to quantify morphological heterogeneity.
- Propensity score matching (PSM) to balance patient groups (normal, circulatory stasis, thrombus).
- Logistic regression and ROC curve analysis to assess risk factors and diagnostic performance.
Main Results:
- LAA FD was significantly higher in patients with LAA thrombus compared to those with circulatory stasis or normal LAA morphology, both before and after PSM.
- LAA FD was identified as an independent risk factor for LAA thrombus and circulatory stasis.
- LAA FD demonstrated superior diagnostic performance in identifying thrombus compared to the CHA₂DS₂-VaSc score.
Conclusions:
- Elevated LAA FD is strongly associated with an increased likelihood of LAA thrombus formation in AF patients.
- LAA FD offers a valuable, quantitative method for assessing thrombosis risk and guiding personalized treatment strategies.
- Incorporating LAA FD into risk stratification may improve the management of AF-related thromboembolic complications.
Purpose:
To assess the anatomical complexity of the left atrial appendage (LAA) using fractal dimension (FD) based on cardiac computed tomography angiography (CTA) and the association between LAA FD and LAA thrombosis.
Materials And Methods:
Patients with atrial fibrillation (AF) who underwent both cardiac CTA and transesophageal echocardiography (TEE) between December 2018 and December 2022 were retrospectively analyzed. Patients were categorized into normal (n = 925), circulatory stasis (n = 82), and thrombus groups (n = 76) based on TEE results and propensity score matching (PSM) was performed for subsequent analysis. FD was calculated to quantify the morphological heterogeneity of LAA. Independent risk factors for thrombus were screened using logistic regression. The diagnostic performance of FD and CHA2DS2-VaSc score for predicting thrombus was evaluated using the area under the receiver operating characteristics curve (AUC).
Results:
LAA FD was higher in the thrombus group (1.61 [1.49, 1.70], P < 0.001) than in the circulatory stasis (1.33 [1.18, 1.47]) and normal groups (1.30 [1.18, 1.42]) both before and after PSM. LAA FD was also an independent risk factor in the thrombus (OR [odds ratio] = 570,861.15 compared to normal, 41,122.87 compared to circulatory stasis; all P < 0.001) and circulatory stasis group (OR = 98.87, P = 0.001) after PSM. The diagnostic performance of LAA FD was significantly better than the CHA2DS2-VaSc score in identifying thrombus.
Conclusions:
Patients with high LAA FD are more likely to develop LAA thrombus, and the use of FD provides an effective method for assessing the risk of thrombosis in AF patients, thereby guiding individualized clinical treatment.
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