To identify risk factors for thrombus formation in the left atrial appendage post-standard anticoagulation treatment by multiple dimensions including the morphology of the left atrial appendage and adjacent structures， echocardiographic imaging， and clinical laboratory indicators.
Methods
This single-center case-control study enrolled patients with non-valvular atrial fibrillation （AF） scheduled for radiofrequency ablation on The Second Affiliated Hospital of Harbin Medical University from January 2021 to October 2022. All patients underwent standardized anticoagulation therapy for at least three weeks before admission.Preoperative examinations included transthoracic echocardiography， transesophageal echocardiography， and pulmonary vein CT angiography. Three-D rendering post-processing techniques to construct three-dimensional structures of the left atrial appendage and pulmonary veins， and multiplanar reconstruction technology to observe the morphology of the left atrial appendage opening were utilized. It also measured the opening's length， diameter， circumference，and area. Clinical datas were collected included patient demographics， comorbidities， liver and kidney function， coagulation parameters， and echocardiographic parameters such as atrial and ventricular diameter and valvular flow velocity. Patients were divided into two groups based on the presence or absence of thrombus in the left atrial appendage as detected by transesophageal echocardiography， and the data differences between the groups were compared.
Results
All of 203 patients were included， averaging （58.13±10.67） years in age， with males comprising 64.5% （131/203）. Among them， 21 patients （10.3%， 21/203） had thrombi in the left atrial appendage， and were classified into the thrombus group， while the remaining 182 （89.6%， 182/203） formed the non-thrombus group. There was no significant statistical difference in the proportions of the four left atrial appendage morphologies （chicken wing， windsock， cactus， and cauliflower） between the two groups. The thrombus group had significantly larger left atrial appendage openings and anteroposterior diameters of the left atrium （P＜0.05）. Binary Logistic regression analysis revealed that increased levels of alanine aminotransferase ［odds ratio（OR）=1.039， 95% confidence interval（CI） 1.009-1.070， P=0.010）］， uric acid （OR=1.005， 95%CI 1.001-1.010， P=0.023）， a decrease in activated partial thromboplastin time （OR=0.919， 95%CI 0.858-0.984， P=0.015）， and an enlarged left atrial appendage opening area （OR=1.793， 95%CI 1.234-2.604， P = 0.003） were independent predictive factors for thrombus formation in the left atrial appendage.
Conclusion
The formation of thrombi in the left atrial appendage of patients with non-valvular AF post-standard anticoagulation during the perioperative period is not related to the morphology of the left atrial appendage. Impaired liver and kidney function are independent risk factors for the formation of thrombi in the left atrial appendage. Maintaining activated partial thromboplastin time at a higher level within the normal range may reduce the risk of thrombus formation. Structural changes in the atrium are also potentially linked to the formation of thrombi in the left atrial appendage.
