CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 4, September/October 2023 AFRICA 235 Clinically, the thrombus in approximately 90% of patients with non-valvular atrial fibrillation is generated from the LAA.11 The LAA is a residual accessory structure of the original left atrium in the embryonic period, with a blind pipe-shaped and long hooked structure, which has a different morphology among individuals and can be divided into windsock, chicken-wing, cactus and cauliflower types.12 The contractile and diastolic function of the LAA is involved in the filling and pressure regulation of the left ventricle, and the blood flow velocity is reduced by vortices easily formed in the LAA due to the abundant pectinate and trabecular muscles with rough surfaces.13 In the case of sinus rhythm, RT-3D-TEE can detect the clear-flow spectra for LAA emptying and filling. For atrial fibrillation patients with a low-flow velocity, however, the left atrium and LAA need to expand the diameter and enhance active contraction to relieve the elevated pressure in the left atrium, thus decreasing the filling and emptying velocity of the LAA.14 Moreover, the LAA cannot be completely emptied because of the widened orifice and irregular inward motion of the atrial appendage wall, so the blood is blocked therein, thereby forming a thrombus. As a result, the LAA becomes a common site of atrial thrombus in atrial fibrillation patients.15 Among the RT-3D-TEE measurement parameters in the present study, the LVEF was lower, whereas the LAD, maximum and minimum diameter of the LAA orifice, and LAA length were larger in group A than in group B. The differential indices indicated that group A had more similar conditions to those of LAA thrombosis and a higher risk of thrombus. According to several studies, the CHA2DS2-VASc score is a recognised, effective method for evaluating the risk of thromboembolism in atrial fibrillation patients and has been proven to be more accurate and valuable in predicting thromboembolism in patients with low-risk stroke.16,17 The study by Proietti et al.18 revealed that the survival curve of atrial fibrillation patients was correlated with the CHA2DS2-VASc score. It was shown in this study that the CHA2DS2-VASc score was negatively associated with the RT-3D-TEE measurement parameter LVEF. However, it was positively correlated with LAD, maximum and minimum diameter of LAA orifice and LAA length. Currently, the RT-3D-TEE technique is extensively applied in clinics and can automatically and clearly display the cardiac morphology and structure as well as quantify the cardiac function free of the impacts of rib and intra-pulmonary air, serving as a gold standard for detecting thrombus in the left atrium and LAA.19 Moreover, the analysis results of ROC curves denoted that the RT-3D-TEE measurement parameters and CHA2DS2-VASc score had similar predictive values, implying that RT-3D-TEE is of high value in predicting risk of LAA thrombosis in atrial fibrillation patients. Although RT-3D-TEE is capable of directly exhibiting the morphology, structure and function of the left atrium and LAA of atrial fibrillation patients, it is characterised by difficulty in operating, certain requirements on doctors and an inability to perform on some patients. As a non-invasive imaging examination, CTA has a shorter scanning time, less radiation is used and simpler operation than RT-3D-TEE, so it is more acceptable. CTA images can not only clearly display the changes in cardiac blood flow and morphology of the left atrium and LAA through post-processing, but also precisely assess the structure and function of patient’s left atrium and LAA, thereby providing a reliable basis for clinical practice.20 Based on the correlations of CHA2DS2-VASc score with CTA-based LAA classification, the CHA2DS2-VASc score had a positive correlation with cauliflower LAA. Cauliflower LAA, the most complicated classification of LAA, has more trabecular muscles formed and lower-flow velocity than chicken-wing LAA. Several studies have demonstrated that cauliflower LAA is an independent risk factor for cerebral stroke, transient ischaemic attack and LAA thrombosis.21,22 In this study, the analysis results of ROC curves revealed that the predictive value of CTA was close to that of the CHA2DS2-VASc score, suggesting that CTA possesses high value in predicting risk of LAA thrombosis in atrial fibrillation patients. There were limitations in this study. For example, the time span of retrospective analysis was large, with certain selection and recall biases. The study data were obtained from a single source, and the sample size was small, so the results need to be further validated by multi-centre studies with larger sample sizes. Conclusion Both CTA and RT-3D-TEE had fairly high predictive values for risk of LAA thrombosis in these atrial fibrillation patients. The CHA2DS2-VASc score could be applied to the clinical prediction of risk of LAA thrombus based on the actual condition of the patients. 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