The Effect Of Biventricular Pacing On Cardiac Function In Third Degree Atrioventricular Block Patients With Preserved Ejection Fraction And Left Ventricular Enlargement

Objective: To compare the effect of biventricular pacing and right ventricular septum pacing on cardiac function and structure in third degree atrioventricular patients with preserved ejection fraction and left ventricular enlargement.To compare the effect of different right ventricular lead location on the therapeutic effect of cardiac resynchronization in patients undergoing biventricular pacing.Methods: Retrospective analysis of 100 third degree atrioventricular block patients with preserved ejection fraction and left ventricular enlargement admitted in our hospital from March 2015 to December 2020 were divided into triple chamber pacemaker group（CRT group）and dual chamber pacemaker（DDD group）,including 44 patients in the CRT group,including 38 patients in CRT-P group and 6 patients in CRT-D group;The DDD group had 56 patients;the right ventricular lead location in CRT group included right ventricular septum and right ventricular apical,and the right ventricular lead location in DDD group only included right ventricular septum.The patients in both groups were followed up for12 months.Changes on NYHA cardiac function grade,QRS duration,echocardiography indexes（Left ventricular ejection fraction,Left ventricular end-diastolic diameter,Left ventricular end-systolic diameter,Left ventricular end-diastolic volume,Left ventricular end-systolic volume,Left atrial diameter,Fraction shortening,Mitral regurgitation）were compared between two groups.LVEDD<55mm at the last follow-up was defined as left ventricular reverse remodeling（LVRR）.Compared the incidence of postoperative LVRR between two groups.According to the different location of right ventricular lead location,the patients in the CRT group were divided into the right ventricular septum pacing group（RVSP）and the right ventricular apical pacing group（RVAP）.Compared the changes of QRS duration and echocardiography indexes（LVEDD,LVEDV）between the two groups in order to assess the effect of different RV pacing sites on the efficacy of CRT.Results: Compared with preoperation（the last follow-up）,the NYHA cardiac function grade improved（p<0.05）,the MR grade dropped（p<0.05）,and the QRS duration was shortened in CRT group（p < 0.05）,the LVEDD,LAD,LVESD,LVEDV,LVESVdecreased（p < 0.05）,the LVEF and FS did not show any significant change after the operation.There was no significant improvement in postoperative NYHA cardiac function grade in the DDD group（p>0.05）,MR grade was aggravated（p<0.05）,QRS duration was longer than preoperation（p < 0.05）,LVEDD,LAD,LVEDV did not change significantly compared with preoperative pacemaker implantation（p > 0.05）,LVESD,LVESV increased（p < 0.05）,LVEF,FS decreased.One patient from CRT group was hospitalized for recurrent heart failure at 12 months post-operative follow up,and five in the DDD group were hospitalized for recurrent heart failure.The incidence of postoperative LVRR was 40.9% in the CRT group and 17.9% in the DDD group,which was statistically significant（p < 0.05）.In patients underwent Biventricular pacing,the postoperative LVEDD,LVEDV and QRS duration between RVAP and RVSP groups were all shortened compared with the preoperative ones,without significant difference in different period between two groups.Conclusion: In third degree atrioventricular block patients with preserved ejection fraction and left ventricular enlargement,Biventricular pacing can reverse ventricular remodeling,reduce the hospitalization rate of patients with recurrent heart failure compared with right ventricular septum pacing.In patients with Biventricular pacing implanted with CRT,right ventricular septum pacing was not superior to right ventricular apical pacing in reversing left ventricular electricalmechanical remodeling.