Long-term Changes In Right Ventricular Apical Pacing Electrode Parameters And Analysis Of Left Ventricular Asynchrony, Morphology And Systolic Function

BackgroundRight ventricular apex(RVA)is the most commonly implanted pacing site in the world.However,because RVA pacing does not pass through the conduction system,but spreads from the apex to the whole ventricular,which leads to unfavorable left ventricular remodeling and wall motion differences,and then affects the cardiac systolic function,resulting in adverse prognosis.Because of the fact that alternative right ventricular pacing has not been confirmed in large randomized studies and lack of strong evidence,it has a high incidence of complications and high cost.Therefore,it is crucial to evaluate the cardiac structure and hemodynamic effects of patients with long-term RVA pacing compared with healthy adults.ObjectiveThe purpose of this study was to determine the changes of electrode parameters in long-term RVA pacing and the differences in left ventricular asynchrony,morphology and systolic function between long-term RVA pacing(pacing ratio>99%)and healthy adults,for better judging the prognosis of RVA pacing and providing clinical guidance.MethodMethods:sixty one patients with complete atrioventricular block(?°AVB)who were admitted for dual-chamber permanent pacemaker replacement(PPM)in Beijing Anzhen Hospital,Capital Medical University,China from May 1,2014 to May 31,2019 were enrolled.At the same time,61 healthy subjects matched with PPM patients in gender,age,follow-up time and complications were included(control group).The electrode impedance,pacing threshold and amplitude of P wave and R wave in PPM group were compared at implantation and follow-up.preimplantation and follow-up mean QRS duration,left atrial anteroposterior diameter(LAD),left ventricular end diastolic diameter(LVEDD),ratio of interventricular septum thickness(IVST)to left ventricular posterior wall thickness(LVPWT),left ventricular mass index(LVMI),left ventricular ejection fraction(LVEF),degree of tricuspid regurgitation and pulmonary artery systolic pressure were measured and compared between PPM group and control group.In order to determine predictors of LVEF decline in PPM group at follow-up,LVEF was used as dependent variable,and electrode parameter,left ventricular dyssynchrony,morphology and systolic function at implantation and long-term follow-up were used as independent variables.ResultAfter 112.44 ± 34.94 months of follow-up,atrial electrode impedance decreased significantly;atrial pacing threshold increased and P-wave amplitude decreased,but there was no significant difference;RVA ventricular electrode threshold increased significantly compared with implantation's,electrode impedance and R-wave amplitude decreased significantly.Compared with healthy group,long-term RVA pacing significantly increased in mean QRS duration,LAD,LVEDD,LVMI,degree of tricuspid regurgitation,and decreased LVEF significantly.However,mean LVEF was still more than 50%LVEF at follow-up,though 9 patients(14.8%)have decreased LVEF by more than 15%.LVEF in PPM group at follow-up was negatively correlated with preimplantation and follow-up LVMI as well as degree of tricuspid regurgitation at follow-up.Conclusion In sum?long-term RVA pacing has certain effects on left ventricular structure and systolic function in ?°AVB patient,but average LVEF is still>50%.Preimplantation high LVMI can predict the decline of LVEF in PPM group at follow-up...