Evaluation Of Left Atrial Structure And Function In Patients With Paroxysmal Atrial Fibrillation Before And After Radio Frequency Catheter Ablation

With the development of social economy,the lifestyle of the Chinese people has changed dramatically and the life expectancy of the population has been greatly increased,therefore,the incidence of cardiovascular diseases in China has been increasing year by year.According to the 2004epidemiological survey in China,the prevalence rate of atrial fibrillation(AF)among people aged 35 to 59 was 0.42%,and that of people aged 60 or above was 1.83%.The United States has an estimated 3 million to 5 million people with AF,compared with an estimated 33 million people worldwide.AF is a very common supra-ventricular arrhythmia that is marked by rapid and irregular activation in the atria without discrete P waves on the body surface electrocardiogram(ECG).AF can be diagnosed with a surface ECG,a transesophageal electrocardiogram,or intracardiac atrial electrocardiogram.Atrial fibrillation generally can be classified in paroxysmal AF(PAF),persistent AF and long-standing persistent AF.PAF is defined as AF that terminates spontaneously or with intervention within 7 days of onset;persistent AF is defined as continuous AF that is sustained beyond 7 days;and long-standing persistent AF is always defined as continuous AF of greater than12 months’duration.Atrial fibrillation not only increases the risk of ischemic stroke,but also is a strongly linked risk factor for congestive heart failure,leading to decreased quality of life and increased financial burden.Catheter ablation is an important treatment opinion for symptomatic atrial fibrillation patients,especially for those with ineffective medication.Unfortunately,after long-term follow-up,the recurrence rate of atrial fibrillation after catheter ablation was as high as 52%.In recent years,the two-dimensional speckle tracking echocardiography(STE)measurement of left atrial two-dimensional strain can be used for assessment of left atrial function,the value of predicting recurrence after radio frequency catheter ablation(RFCA)of atrial fibrillation in patients with atrial fibrillation clinical acceptance.Recent studies have shown that three-dimensional echocardiography can evaluate the strain and non-synchronism of the left atrium with good repeatability,and which is simpler and faster than two-dimensional strain echocardiography.Three-dimensional echocardiogra-phic assessment of left atrial synchronicity help predicting whether normal or mildly expanded left atrial size and normal left ventricular systolic function of patients with paroxysmal atrial fibrillation after radio frequency catheter ablation recurrence,but it is not clear.In the guidelines,radio frequency catheter ablation is recommended for patients with symptomatic PAF who have failed AAD therapy.RFCA is widely accepted as a minimally invasive treatment of AF which can generate energy lesions on the atrial muscle cells around the pulmonary vein,produce thermal damage,cause myocardial cell dehydration,solidification,necrosis,reduce melting line near the atrial muscle cells number,atrial muscle contraction force may fall.Over time,inflammation,edema,postoperative scar tissue contraction,left atrium structure reconstruction to a certain extent.Radio frequency energy itself in the process of the application of RFCA may be the cause of atrial muscle cell damage,thus affecting left atrial structure and function,but maintaining sinus rhythm after ablation is helpful for the improvement of the atrial structure and function.The combined effect of the two modeling in patients with paroxysmal atrial fibrillation who receive RFCA is an urgent issue to be discussed.It is generally accepted that anti-coagulation therapy for patients with atrial fibrillation can reduce the incidence of thrombosis and thromboembolic stroke.However,due to poor patient compliance,the rate of adherence to anti-coagulation therapy is only 2.0%to 6.6%.CHADS2 score is currently the most widely used scoring system for predicting stroke risk.Since 2010,the guideline of treatment of atrial fibrillation issued by the European society of cardiology recommends CHA2DS2-VASc,a modified scoring system,which is more and more used in patients with non-valvular atrial fibrillation thromboembolism risk assessment,to guide the use of anticoagulants.However,it is not clear whether the echocardiographic parameters,CHADS2score and CHA2DS2-VASc can accurately predict left atrial/left atrial appendage(LA)thrombosis in patients with no-valve AF.Part one Real time three-dimensional echocardiography assessment of left atrial synchrony predicts recurrence of paroxysmal atrial fibrillationObjective:The aim of this study was to investigate whether LA volumes,functions and dyssynchrony were related to recurrence of paroxysmal atrial fibrillation(PAF)in patients with normal left ventricular(LV)systolic function,and normal or mildly enlarged left atrial volume,using real time three-dimensional echocardiography imaging(RT 3DE).Methods:From January 2012 to March 2014,158 patients with paroxysmal atrial fibrillation underwent radio frequency catheter ablation in our hospital.Patients with paroxysmal atrial fibrillation(AF)and normal or mildly enlarged of the left atrial volume,normal left ventricular systolic function were included.All patients were admitted for their first admission of pulmonary venous isolation.Exclusion criteria:1.age<18 years,2.left atrium enlargement(volume index>41 mL/m~2),3.left ventricular ejection fraction<55%),4.patients with pregnant,5.patients with structural heart diseases,6.patients with old myocardial infarction,7.history of open chest surgery,8.patients with secondary pulmonary vein isolation technique,9.patients with moderate to severe valvular dysfunction,10.other cardiac arrhythmias.Eighty-eight of the patients met the inclusion criteria(60±10years old,63%male).All patients underwent echocardiography examination during sinus rhythm before radio frequency catheter ablation 24 hours.Left atrial anteroposterior diameter(LAD),left ventricular end diastole anteroposterior diameter(LVEDD),left ventricular end diastole anteropo-sterior diameter(LVESD),left ventricular end-diastolic volume(LVEDV),left ventricular end systolic volume(LVESV),left ventricular ejection fraction(LVEF)and mitral valve flow early diastolic velocity(E wave)and atrial systolic velocity(A wave),ratio of E wave and A wave(E/A),left atrial volumes,including left atrial maximum volume(LAV-max),left atrial minimum volume(LAV-min),and left atrial pre-atrium contraction volume(LAV-preA),left atrial ejection fractions including left atrial total ejection fraction,passive and active ejection fraction.LA dyssynchrony was quantified by the standard deviation of time to left atrial minimum systolic volume(LA Tmsv-SD)from end-diastole by real time three-dimensional echocardiography(RT 3DE).Results:1.After 11.7±3.6 months of follow-up,67 patients were free of AF recurrence but 21 patients failed,and the recurrence rate of atrial fibrillation was 24%.There was no difference in age,gender,weight,height,body surface area,combined disease,CHADS2 score,and history time of atrial fibrillation between the without recurrence group and the recurrence group.2.Patients with recurrence of AF after RFCA showed greater LA Tmsv-SD compared with patients without recurrence(P<0.001).3.There were no differences in LV dimensions or volumes,LV diastolic function parameters including mitral E and A velocities,E/A ratio,deceleration time,e’,E/e’between the two groups.4.There were no difference in LA volumes and LAEFs by RT 3DE and LA GLS by two-dimensional speckle-tracking imaging between patients with and without recurrence of AF after RFCA.5.LA Tmsv-SD was the predictor of PAF in a multivariate logistic regression analysis.The ROC analysis demonstrated that LA Tmsv-SD(AUC=0.88)of 14.5ms was the optimal cut-off value to discriminate patients with recurrence AF from patients without recurrence AF with a sensitivity of 95.2%and a specificity of 68.7%.Conclusions:1.LA Tmsv-SD was larger in the recurrence group than without recurrence group.2.LA Tmsv-SD is the predictor of PAF recurrence after RFCA.3.LA Tmsv-SD 14.5ms in RT 3DE predicts patients with paroxysmal atrial fibrillation with normal or mildly enlarged left atrial volume and normal left ventricular systolic function recurrence after radio frequency catheter ablation of sensitivity 95.2%,specificity 68.7%.Part two Characteristic changes of volume and structure of the left atrium in patients with paroxysmal atrial fibrillation after catheter ablationObjective:to observe the effect of radio frequency catheter ablation on the structure and function of left atrium(LA)in paroxysmal atrial fibrillation(PAF)patients with normal left atrial volume index(LAVI)and enlarged LAVI.Methods:51 patients with paroxysmal atrial fibrillation were included in our study.Patients were divided into group 1 with normal LAVI(LAVI≤34mL/m~2,n=40)and group 2 with enlarged LAVI(LAVI>34 mL/m~2,n=11).Transthoracic echocardiogram was performed at pre-ablation,and 3,6,and 12months post-ablation.Left ventricular end diastole anteroposterior diameter(LVEDD),left ventricular end diastole anteroposterior diameter(LVESD),left ventricular end-diastolic volume(LVEDV),left ventricular end-systolic volume(LVESV),left ventricular ejection fraction(LVEF)and mitral valve flow early diastolic velocity(E wave)and atrial systolic velocity(A wave),ratio of E wave and A wave(E/A).Left atrial structure indexes were also measured including the left anterior-post diameter(LAD),left atrial maximum volume(LAV-max),left atrial minimum volume(LAV-min),left atrial pre-atrium contraction volume(LAV-preA).The changes of left atrial functions were examined by calculating left atrial passive ejection fraction(LAEF passive),left atrial active ejection fraction(LAEF active),left atrial total ejection fraction(LAEF total),LA global longitude strain and LA strain rates.Results:1.Patients in group 2 were much older(63.6±4.5 vs 58.0±9.9 years,P=0.011)and with more longer atrial fibrillation history(80.6±19.4 vs10.6±7.6 months,P=0.015)as compared to group 1.2.Patients in group 2 with larger LAD,LAV-max,LAV-min and LAV-preA(37.4±3.6 vs 33.5±4.4mm,75.7±11.7ml vs 50.1±10.8ml,60.3±8.5ml vs 37.4±9.2ml,42.6±9.3ml vs 23.0±6.9ml;P=0.003,<0.001,<0.001,<0.001)as compared to group 1.3.Group 2 have lower LAEF active,LAEF total,LA strain and LA strain rates(43.7±8.5%vs 54.3±8.9%,29.8±7.6%vs 38.6±9.4%;31.68±4.32%vs40.89±8.04%,1.35±0.30%vs 1.79±0.41%,-1.55±0.30%vs-2.17±0.65%,-1.85%(-2.30,-1.25)vs-2.85%(-3.10,-2.30);P=0.001,0.006,<0.001,0.002,0.002,<0.001,separately)as compared to group 1.4.LAV-max significantly decreased at 3 months after ablation in group 2,but no further decrease was observed at 6 month and 12 months.However,no change was found in diameter and volumes of LA in group 1.5.LA A-SR was significantly decreased at 3 month and 6 months after ablation in the group 1,but no change of LA function was found in group 2.Conclusions:1.Patients with larger LA volume were older and with longer AF history as compared to patients with normal LA volume,and patients with larger LA volume have lower LAEF and LA strain and strain rates.2.Radio frequency catheter ablation could reduce the increased left atrial structure,especially in patients with larger LA volume.3.Radio frequency catheter ablation can reduce LA A-SR in patients with normal left atrium size.Part three Echocardiographic parameters,CHA2DS2-VASc and CHADS2 score predict left atrial thrombus and thrombus high risk in Non-Valvular Atrial FibrillationObjective:To explore the clinical value of echocardiographic parameters,CHA2DS2-VASc score and CHADS2 score risk stratification schemes with respect to their ability to predict LAA thrombus in transesophageal echocardiography of patients with non-valvular atrial fibrillation.Methods:According to TEE results,923 patients with non-valvular atrial fibrillation were divided into all AF patients with LA thrombus and without,all AF patients with LA thrombus high risk and without,PAF patients with LA thrombus and without,PAF patients with LA thrombus high risk and without.The patients’CHA2DS2-VASc and CHADS2 risk scores and categories were also calculated.Comparing the predictive value of CHA2DS2-VASc and CHADS2 scores for risk stratification of LA thrombosis in patients with non-valvular atrial fibrillation is on the basis of the receiver-operating characteristic curve(ROC curve).Results:Two scoring criteria were applied to 923 patients with non-valvular atrial fibrillation.The proportions of LA thrombus and LA thrombus high risk were higher in high CHADS2 and CHA2DS2-VASc score groups.The area under the curve(AUC)concerning the prediction of LA thrombus and LA thrombus high risk were similar using CHADS2 and CHA2DS2-VASc.The new models which including echocardiographic parameters and clinical risk factors had higher AUC comparing with CHADS2and CHA2DS2-VASc score with 0.834(95%CI 0.808 to 0.857),sensitivity67.6%,specificity 89.0%,cut value>1;0.828(95%CI 0.802 to 0.851),sensitivity65.3%,specificity88.6%,cut value>1;0.832(95%CI 0.805 to0.857),sensitivity 84.6%,specificity69.6%,cut value>0;0.835(95%CI 0.808to 0.859),sensitivity 66.7%,specificity88.6%,cut value>1.Conclusions:1.With the increase of CHADS2 and CHA2DS2-VASc score risk stratification,the risk of LA thrombus and high risk of thrombus in patients with NVAF increases gradually.2.The overall ability of CHADS2 score to predict LA thrombus and thrombus high risk in patients with non-valvular atrial fibrillation was the same as CHA2DS2-VASc.3.It is demonstrated that new models which including echocardiographic parameters and clinical risk factors have higher ability to predict LA thrombus and LA thrombus high risk in NVAF.