Investigation Of Influencing Factors For Left Atrial Appendage Slow Flow Velocity In Non-valvular Atrial Fibrillation

Background and objectivesNon-valvular atrial fibrillation(NVAF)represents a irregular and disordered electrical conduction activity in the atrium,which is the most common continuous arrythmia in encountered in clinical work.Significant disturbances in atrial electrical activity affects the contraction and diastole of the atrium,leading to blood stasis and the formation of thrombus.It has been found that left atrial thrombi are mainly situated in the left atrial appendage.The slow flow velocity of left atrial appendage is one of the essential reasons of left atrial thrombogenesis.Researches about the influencing factors of left atrial appendage flow velocity(LAAFV)are sparse.This study aimed to explore the influencing factors for blood flow velocity in left atrial appendage in subjects with atrial fibrillation.MethodsA total of 114 hospitalized patients with NVAF were enrolled.Baseline clinical characteristics of the subjects were collected.Laboratory parameters including coagulant factors' activities,biochemistry,etc.were measured.Transthoracic echocardiography and transesophageal echocardiography were performed.The left atrial appendage flow velocity was detected by transesophageal echocardiography.According to that,the subjects were classified into two groups:slow LAAFV group(<40cm/s,n=40),and normal LAAFV group(?40cm/s,n=74).ResultsIn terms of atrial morphology,the left ventricular end diastolic diameter(P=0.016),anterior-posterior diameter(P<0.001),superior-inferior diameter(P<0.001)and left-right diameter(P<0.001)of the left atrium,left atrial volume(P<0.001)and the degree of mitral regurgitation(P=0.009)are significant different.In addition,the correlation analysis showed a negative correlation with LAAFV(r<0,P<0.05)except left ventricular end diastolic diameter.However,left ventricular ejection fraction and left ventricular diastolic function were not statistically different between the two groups(P>0.05).For coagulation-related indicators,blood D-dimer concentration(P=0.027)and coagulation factor ?(P=0.008),?(P=0.006)activity were significantly different between the two groups.Correlation analysis showed that the activity of coagulation factors ?,?,?,? was weakly positively correlated with LAAFV(r>0,P<0.05),whereas the activity of coagulation factor ? was negatively correlated with it(r<0,P=0.014).There was no significant difference between activated partial thromboplastin time(APTT),prothrombin time(PT),thrombin time(TT),D-dimer,fibrinogen and coagulation factors,?,? and LAAFV(P>0.05).Among the other indicators,there was a significant difference between the two groups,including N-terminal B-type natriuretic peptide(NT-proBNP)(P<0.001),and aspartate aminotransferase(AST)(P<0.001).While there was no significant difference in serum creatinine,alanine aminotransferase and bilirubin between two groups(P>0.05).For baseline clinical data,the history of ischemic stroke(P=0.035),type of atrial fibrillation(P<0.001)and the events of left atrial thrombus(P=0.039)were statistically different between the two groups.However there was no significance in age,history of heart failure,diabetes,hypertension,tobacco,alcohol intake and CHA2DS2-VASc scores(P>0.05)between two groups.Multivariate linear regression analysis suggested that left atrial volume,superior-inferior diameter of left atrium(LA-SID)and NT-proBNP were independent influencing factors of LAAFV(P<0.05).ConclusionsIn patients with NVAF,left atrial volume,superior-inferior diameter of left atrium(LA-SID)and NT-proBNP were independently associated with LAAFV In view of the morphology,left atrial volume,the left atrial diameter,left ventricular end diastolic diameter and mitral regurgitation are related to LAAFV,except left ventricular end diastolic diameter,cardiac contraction and diastolic function.In light of coagulation-related indicators the activities of coagulation factors ?,?,?,and ?were positively correlated with the blood flow velocity of the left atrial appendage,while the activities of coagulation factor VIII was negatively correlated.However,the concentration of D-dimer and fibrinogen,the activities of factors ?,? and APTT,PT and TT in response to coagulation were not significantly correlated with LAAFV Among the other indicators,the levels of NT-proBNP and AST in the blood were higher in the slow LAAFV,while serum creatinine,bilirubin and ALT were not significantly different between the two groups.In the baseline data,the LAAFV subjects had a higher proportion of history of ischemic stroke,and induced more atrial thrombosis.However,there was no significant difference between the history of heart failure,hypertension,diabetes,coronary heart disease,smoking and alcohol intake compared with normal LAAFV There was no significant difference in age and gender between two groups.However,the proportion of types of atrial fibrillation was higher in the slow LAAFV.