The Influence Of Cardiac Resynchronization Threapy On Ventricular Remodeling In Patients Of Third Degree Atrioventricular Block With Systolic Dysfunction

This research concludes two phase.The first phase:Objective Several studies have confirmed that right ventricular apex pacing can cause abnormal conduction which is similar to left bundle branch block,makes the activation originate from right ventricular,pass through the interventricular septum by myocardial cells to the left ventricular,and the posterior or posterolateral basal LV is the latest activated region.This causes the paradoxical septal motion,interventricular and intraventricular dyssynchrony.Long time,high rate right ventricular pacing can damage the cardiac function severely,even develops to heart failure,it is especially apparent in patients who already have cardiac dysfunction.At present researches about other pace points in right ventricular,such as septum,outflow have not found evidence that these points are better than right ventricular apex.Meanwhile,His-bundle pacing still cannot use in clinical practice due to high technical requirements,and can not apply to patients with conduction block under the His-bundle.Cardiac resynchronization therapy(cardiac resynchronization threapy,CRT)can correct the dyssynchronous activation caused by the right ventricular pacing,maybe can avoid the negative impact of the right ventricular pacing.This research is to discuss the effect of cardiac resynchronization threapy(CRT)to cardiac function and left ventricular remodeling in patients of third degree atrioventricular block(AVB)with systolic dysfunction by observing changes of echocardiography indexes including left ventricular ejection fraction(LVEF),left ventricular end systolic volume(LVESV),left ventricular end-diastolic volume(LVEDV),left ventricular end-diastolic diameter(LVEDD),left ventricular end systolic diameter(LVESD),mitral regurgitation(MR)classification after implanting CRT device.Methods Patients of third degree atrioventricular block with an LV end-diastolic diameter?55mm and an ejection fraction?50%,New York Heart Association(NYHA)class I,II,or III who underwent CRT were enrolled in this study from January 2009 to October 2014.Excluding patients with previous receipt of a cardiac implantable electrical device(whether subsequently removed or remaining),unstable angina,acute myocardial infarction,percutaneous or surgical coronary intervention within 30 days before enrollment,valvular disease with an indication for valve repair or replacement,life expectancy<1 year.Collect baseline characteristics of patients such as age,sex,basal diseases,QRS duration ? morphology and echocardiography indexes before implantation.Optimal medicine therapy was given to patients with existence of the signs and symptoms of cardiac dysfunction to make cardiac function stability.The echocardiography was performed preoperative,six months and twelve months of postoperative respectively,regarding the LVEF ? LVESV as major indexes,combine with LVEDV,LVEDD,LVESD,MR grade to observe the changes of cardiac function and left ventricular remodeling.Results 49 patients were enrolled toally,and the LVEF increased gradually at postoperative,it increased 3.22�2.91%(P <0.05)compared to preoperative when 6 months after surgery,and increased 5.02�6.52%(P <0.05)at 12 months further;LVESV was decreased gradually.it declined 25.02�17.95 ml at 6 months(P<0.05),and further down 24.79�22.49ml(P<0.05)at 12months;other indexes also were improved,LVEDV decreased 25.61�24.24ml(P<0.05),LVEDD decreased 3.22�2.91mm(P<0.05),LVESD decreased 4.43� 2.86mm(P<0.05),MR grade dropped 0.49�0.76(P<0.05),these indexes reduced sequentially at 12 months compared to 6months,LVEDV decreased 28.18�22.36ml(P<0.05),LVEDD decreased 4.17�3.14mm(P<0.05),LVESD decreased 4.92�4.40mm(P<0.01),MR grade dropped 0.22�0.55grade(P<0.05).Objective To analyze the predictors of ventricular reverse remodeling in patients with third degree atrioventricular block and left ventricular systolic dysfunction after cardiac resynchronization therapy.Methods Patients with third degree atrioventricular block and left ventricular systolic dysfunction who received CRT in our ceter were enrolled in this study from January 2009 to May 2015,baseline clinical data and postoperative follow-up data were analyzed.Left ventricular end systolic volume(LVESV)decreased more than 15% or left ventricular ejection fraction(LVEF)increased more than 5% within 12 months after CRT was defined as left ventricular reverse remodeling.Patients were divided into reversal group and no reversal group,comparing the clinical data between these groups.And using two classification Logisitic regression model to analyze the predictive factors for CRT to reverse left ventricular remodeling.Results A total of 65 patients were enrolled,the average age was(62 + 14)years old,following up 12 months.Ventricular reverse remodeling occurred in 36 patients(55.4%).The percentage of female(25/11,P=0.011),baseline QRS width >120ms(27/12,P=0.001),interventricular mechanical delay(IVMD)?40ms(30/18,P=0.027)and the standard deviation of time-to-minimum systolic volume of the 16 left ventricular segments expressed in percentage of R-R duration,Tmsv16-SD(%R-R))?8.3%(28/10,P=0.001)were higher in reversal group than no reversal group,two classification logisitic regression analysis showed that female(OR=6.228,95%CI 1.561~24.842,P=0.01),the duration of QRS >120ms(OR=7.77895%CI 1.996~30.769,P=0.003)and Tmsv16-SD(%R-R)?8.3%(OR=8.134,95%CI2.064~32.057,P=0.003)were independent predictors of ventricular remodeling reversal.Conclusion For patients of third degree AVB with systolic dysfunction,CRT is a beneficial pacing mode and therapy technique.CRT can increase the LVEF,reduce the LVESV,reverse left ventricular remodeling and improve cardiac function.And for these patients,female,QRS>120ms and Tmsv16-SD(%R-R)? 8.3% were predictors of left ventricular reverse remodeling by CRT.