The Risk Factor Of Thrombus Formation And The Effect Of Catheter Ablation On Repetitive Thrombus Formation In Patients With Atrial Fibrillation

Background and ObjectiveAtrial fibrillation(AF)is the most common sustained cardiac arrhythmia in adults.AF patients are at great risk for potential thrombosis.The vast majority of nonvalvular atrial fibrillation(NVAF)strokes are caused by embolism due to the shedding of a LAA-derived thrombus.The CHA2DS2-VASc score is the most predominantly used AF stroke risk stratification scheme to predict thromboembolic events.Previous studies have demonstrated that even AF patients with a low CHA2DS2-VASc score were likely to experience thromboembolic events.At the same time,the scoring system did not include all risk factors for atrial thrombosis.Transesophageal echocardiography(TEE)is currently the preferred examination for evaluating atrial thrombus.In this study,we attempted to use TEE to detect atrial thrombus,analyze the basic clinical characteristics of patients with thrombosis,summarize their echocardiographic and other parameters,and calculate the CHA2DS2-VASc score of patients,so as to evaluate the risk factors of atrial thrombus in patients with AF.Treatment for intra-atrial thrombus has been suggested with vitamin K antagonists or non-vitamin K antagonist oral anticoagulants.However,strategies to further manage of patients after thrombolysis,such as continued use of anticoagulants or rhythm control,is unknown.Effective management of patients can prevent thrombus re-formation and even cardiogenic stroke.Catheter ablation(CA)can restore sinus rhythm in patients with atrial fibrillation and increase the left atrial appendage flow velocity(LAAFV),thereby reducing or even reversing the risk of thrombosis.Therefore,at a follow-up of at least 1 year,sinus rhythm maintenance,thrombosis re-formation,and cerebral ischemic lesions were assessed in patients with AF who underwent CA after atrial thrombolysis.Methods1.This single-center study reviewed patients with AF underwent CA between January 2015 and June 2020,1726 patients were included,among which 58 patients had a history of intracardiac thrombus diagnosed with routine TEE prior to CA.According to the examination results,patients were divided into non-intracardiac thrombus and intracardiac thrombus groups.In addition,left atrial appendage flow velocity was measured and recorded.For each index,univariate logistic regression analysis was firstly adopted,followed by multivariate logistic regression analysis.According to the results and combined with CHA2DS2-VASc score,ROC curve was drawn,area under curve(AUC)was calculated,and risk factors were assessed.2.In this study,1726 patients mentioned above were followed for at least 1 year,including 58 patients who underwent catheter ablation after atrial thrombolysis.Thromboembolic events and bleeding events were recorded during the follow-up,and the recurrence of atrial tachyarrhythmia was collected.According to inclusion and exclusion criteria,27 patients were screened out and divided into postoperative recurrence group and non-recurrence group.TEE and brain MRI were performed at the latest follow-up to assess atrial thrombosis recurrence,LAAFV,and cerebral ischemic lesions.Results1.In this study,58 out of the 1726 patients(3.36%)developed intracardiac thrombus.Among the examined baseline characteristics,BMI,AF type,and renal dysfunction were significantly different between the two groups(p<0.05).The CHA2DS2-VASc scores of the two groups did not differ significantly.Regarding risk factors of cardiac thrombus formation,BMI,AF type,and renal dysfunction showed statistical significance(p<0.05),which was included in the multivariate logistic model.The results demonstrated that persistent AF is the only independent risk factor affecting the formation of atrial thrombus(OR 3.152;95%CI,1.806 to 5.500;p<0.001).The ROC curves showed that the combination of CHA2DS2-VASc score,AF type,renal dysfunction,and BMI was of higher predictive value(AUC,0.70).It is suggested that CHA2DS2-VASc score combined with persistent AF,BMI and renal dysfunction can predict the formation of atrial thrombosis to a certain extent.2.During follow-up,LAAFV presented with a significant increase among patients with sustainable sinus rhythm(n=15,pre and post-CA difference 17.46±14.81cm/s,p<0.001),no significant change was observed in recurrent tachyarrhythmia patients(n=12,4.46±10.84cm/s,p>0.05).The incidence of the documented recurrence of atrial tachyarrhythmia of the thrombus group was significantly higher than that of the no-thrombus group(23/58,39.66%vs.410/1668,24.58%,p<0.05).In the Cox regression analysis,patients with atrial thrombus had worse outcomes compared with those without atrial thrombus(HR,1.656;95%CI,1.084 to 2.530;p=0.02),after adjusting for age,sex,BMI,and the type of AF.Conclusion1.Persistent AF is an independent risk factor for thrombus formation.2.Catheter ablation can help maintain sinus rhythm effectively in AF patients with a history of atrial thrombus.3.Successful CA may improve the LAAFV and thereby decrease the risk of intracardiac thrombus formation.