The Relationship Between Lead V₁/I And Left Ventricular Remodeling After Cardiac Resynchronization Therapy In Heart Failure

BackgroundsCardiac resynchronization therapy(CRT)is one of the important methods for the treatment of heart failure with myocardial asynchrony decreased ejection fraction in recent years.Patients with heart failure are prone to leading to atrioventricular,interventricular and intraventricular conduction delays due to potential myocardial tissue damage,resulting in non-synchronous contraction between the left and right ventricles,resulting in ejection fraction(EF)decreased,increasing ventricular end-diastolic diameter(LVEDD),increasing left ventricular end-diastolic volume(LVEDV),mitral regurgitation and QRS waves broadening,left bundle branch block(LBBB)and other electrical remodeling,thus,which increases the mortality of patients with heart failure,and affects the long-term prognosis of the patients.Cardiac resynchronization therapy can improve the symptoms and quality of life of patients with heart failure by restoring coordinated contraction between left and right ventricles and improving electrical remodeling,and then,reduce the rate of rehospitalization and mortality.The guidelines recommend that patients who benefit from CRT treatment according to the duration of QRS waves and the morphology of left bundle branch block before operation.However,even among patients carefully screened according to the guidelines,only about two-thirds of patients would benefit from CRT treatment.CRT non-responder may be related to many factors,among which the asynchrony of interventricular mechanical contraction and electrical conduction are important factors for CRT responder.However,the previous studies focused on identifying the morphological characteristics of preoperative ECG in patients with heart failure to identify the beneficiaries of CRT.The few studies have assessed patients' response to CRT by interpreting pacing electrocardiograms after CRT.Therefore,this study attempts to evaluate a method based on pacing electrocardiogram after CRT to predict whether the first routine 12-lead electrocardiogram after CRT is related to the improvement of left ventricular ejection fraction(LVEF).ObjectiveThe purpose of our study was to evaluate whether QRS morphology in Vi lead and/or I lead(suggesting posterolateral capture of left ventricle)were associated with left ventricular remodeling in the first routine 12-lead ECG after operation.Methods89 patients with heart failure treated with CRT in our hospital from June 2014 to December 2018 were analyzed retrospectively.The patients were divided into two groups:biventricular pacemaker QRS morphology group(n=51)and non-biventricular pacemaker QRS morphology group(n=38).The baseline general clinical data,the first routine 12-lead ECG before and after CRT and results of routine echocardiography more than 6 months after operation were analyzed retrospectively.The QRS morphology of biventricular pacing is defined as V1 lead R/S?1 and/or I lead R/S?1.CRT reactions was defined as an increase in left ventricular ejection fraction(LVEF)by more than 5%after CRT.ResultsAmong the 89 patients,the average age was 57.4 years old.51%of the patients were female,and the average baseline LVEF was 30%.74.2%of the patients were left bundle branch block,and the other 25.8%were non-left bundle branch block.42%of the patients NYHA cardiac function grade was ? grade,38%of the patients' cardiac function grade was ? grade,and 9%of the patients' cardiac function grade was ? grade.The general clinical data and the results of preoperative electrocardiogram and echocardiography(NYHA grade,drug use,QRS duration,QRS morphology,preoperative LEVF,preoperative LVEDD,left ventricular electrode position,etc.)were similar between the two groups,but there was no significant difference in baseline data between the two groups.Among the 89 patients,51(57.3%)had a response to CRT,and 40(78.4%)of the them met our definition of the QRS morphology of our biventricular pacing.Of the 38 patients(42.7%)who did not response to CRT,27(71.1%)did not met our definition of the QRS morphology of our biventricular pacing.Response to CRT was significantly correlated with the QRS morphology of our biventricular pacing(X2=21.79,P<0.001).The improvement of ejection fraction in patients with biventricular pacing QRS morphology was significantly higher than that in patients with non-compliance(14.8%vs 3.29%,P<0.001).The mean end diastolic diameter of left ventricle was significantly shorter than that of nonconforming patients(9.5 vs 3.8mm,P=0.010).In the subgroup analysis of 23 non-LBBB patients.10 patients with biventricular pacing,7 patients(70%)had improved LVEF.In 13 patients w who did not conform to our biventricular pacemaker QRS morphology.The LVEF of 9 patients did not improve.ConclusionsThe study shows the importance of QRS morphology in postoperative 12-lead ECG for the curative effect of CRT.In addition,subgroup analysis showed that patients with heart failure without left bundle branch block could still benefit from CRT if the ECG conformed to the QRS morphology of biventricular pacing.