Analysis Of Risk Factors For Left Atrium/Left Atrial Appendage Thrombosis In Patients With Nonvalvular Atrial Fibrillation

Research backgroud:Nonvalvular atrial fibrillation is the independent risk factors of stroke of embolism.Although guidelines recommend effective anticoagulant therapy to prevent AF related embolism based on risk factors,but stroke caused by atrial fibrillation still occupied a quarter of the elderly patients with stroke.So it is necessary to explore other stroke risk factors beyond what guidelines recommend.Welch proposed in 1909 cardiac stroke associated atrial fibrillation is mainly due to LAA thrombus,so it is extremely important to early diagnose or find LA/LAA thrombus for patients with nonvalvular atrial fibrillation.Especially theses risk factors leading to LAA thrombus.In 2010,wang,etc firstly divided the LAA morphology into four types,namely “Chicken” 、 “Wing” 、 “Cauliflower” 、 “Cactus” and “Windsock”,to guide the LAA closure.Di Biase,etc then reported that different LAA morphology have certain relevance with stroke/TIA.They also point out that compared with other LAA morphology,the “Chicken ”LAA morphology which has a clear bend in the main lobe is less likely to form thrombus.These important findings arouse widespread attention.Kimura found "cauliflower" LAA morphology has a close correlation with stroke/TIA.Obviously,all these studies reveal that stroke has a close relationship with LA/LAA thrombus.So we speculated that the LAA morphology is a powerful predictor for LA/LAA thrombus in non-valvular atrial fibrillation.LAA morphology should be included in the risk factors of LA/LAA thrombus.The present commonly used CHADS₂ score and CHA₂DS₂ VASc score have certain predictive value for LA/LAA thrombus.Though they are practical,the risk factors of these scoring system are relatively limited and less than half what we have recognize now,meaning that many other important risk factors have not been taken into account,such aslower creatinine clearance,increased LA diameter,persistent AF,LAA morphology,etc.So if we could explore out a more practical stroke risk stratification schemes,then the anticoagulant therapy in patients with atrial fibrillation will be more effective,and will also reduce the risk of hemorrhage due to unnecessary anticoagulant therapy.Research objectives:The purpose of this research is to explore the correlation of LAA morphology with LA/LAA thrombus in patients with nonvalvular atrial fibrillation and then straightforward whether LAA morphology can act as a predictor of stroke in patients with nonvalvular atrial fibrillation,suppling the scoring system of CHADS₂ score and CHA₂DS₂-VASc score,so as to guide anticoagulant therapy for patients with nonvalvular atrial fibrillation,reducing the risk of stroke.Research method:This study is a single-center,retrospective analysis.Data from 555 patients in whom transesophageal echocardiography was performed for screening before direct-current cardioversion or radiofrequency ablation between January 2009 and June 2014 in changhai hospital were analyzed.All patients were seperated into two groups-thrombus group and non-thrombus group which is based on transesophageal echocardiography.The morphology of left atrial appendage is reconstructed through the CT and is divided into four types,namely “Chicken Wing”,“Cauliflower”,“Cactus” and “Windsock”.CHA₂ DS score and CHA₂DS₂-Va Sc score are calculated in all patients.We compare the clinical data of the two group and find the strongest risk factors associated with LA/LAA thrombus with multi-factor logistic regression analysis.And then to rebuild a new scoring system to predicte LA/LAA thrombus.Finally compare the new score system with CHADS₂ score and CHA₂DS₂-VASc score system to predict ability of LA/LAA thrombus.Research result:1.General information the thrombus group and non-thrombus group have no statistically significant difference in the morbidity of hypertension,diabetes,stoke/TIA,vascular disease.Heart failure,renal insufficiency have statistically significant difference,the morbidity is 5.9% and 20% respectively,17.1% and 2.9% respectively,p is 0.003 and 0.000 respectively.The morbidity rates of the thrombus group is higher than the non-thrombus group in heart failure and renal insufficiency.In these risk factors,hypertension is the most common risk factors for this study,the prevalence of hypertension in the general population（47.7%）,thrombus group（48.6%）and non-thrombus group（47.7%）are the highest.2.Molecular markers In these data,BNP、D2、 Fg、 e GFR are statistically significant difference in thrombosis and non-thrombosis group.Lp（a）have no statistically significant difference.The results of logistic regression analysis showed that is D2（OR:1.74;95%CI:1.073-2.807;p:0.025）、BNP（OR:3.00;95%CI:1.709-9.677;p:0.002）were independent risk factor for thrombosis.3.The LAA morphology observation LAA external diameter 、 LAA internal diameter、LAA volume、 LA diameter、the proportion of the three different LAA morphology “Chicken ”、“Cauliflower”、“Cactus” are statistically significant difference in thrombosis and non-thrombosis group,the proportion of the “Windsock” LAA morphology have no statistically significant difference.The results of logistic regression analysis showed that is LA diameter（OR:4.07;95%CI:1.709-9.677;p:0.002）、non-persistent atrial fibrillation（OR:5.14;95%CI:1.911-13.818;p:0.001）、non-“Chicken Wing” LAA morphology（OR:11.48;95%CI:4.157-31.684;p:0.000）were independent risk factor for thrombosis.The OR of non-“Chicken Wing” LAA morphology is 11.48 and is highest.When considering other risk factors,including CHA₂DS₂ score and CHA₂DS₂-VASc score,non-“Chicken Wing” LAA morphology has the most obvious correlation with LA/LAA thrombus.We think the LAA morphology may be useful for predicting LA/LAA thrombus in patients with nonvalvular atrial fibrillation.So we creat L2CHADS₂ score on the basis of the CHADS₂ score,giving the “Chicken Wing” LAA morphology 2points.When the cut point is 1,1 and 2 respectively,their sensitivity and specific of CHADS₂ score,CHA₂DS₂-VASc score,L2CHADS₂ score were 0.657 and 0.427,0.886 and 0.225,0.886 and 0.225.AUC is 0.558,0.557 and 0.767 respectively.The AUC of L2CHADS₂ score is significantly higher than the CHADS₂,CHA₂DS₂-VASc score,while there is no obvious difference between CHADS₂ score and CHA₂DS₂-VASc score.The positive predictive value and negative predictive value of L2CHADS₂ score are higher than CHADS₂ score and CHA₂DS₂-VASc score.Conclusion: According to our research results,non-“Chicken Wing” LAA morphology is a powerful predictor for LA/LAA thrombus in non-valvular atrial fibrillation.LAA morphology should be included in the risk factors of LA/LAA thrombusis.The sensitivity and AUC of L2CHADS₂ score are higher than CHADS₂ score and CHA₂DS₂-VASc score,and the specificity of L2CHADS₂ score is higher than the CHADS₂ score,and is the same as CHA₂DS₂-VASc score.