Outcomes Of His-Purkinje System Pacing In Patients With Typical Left Bundle Branch Block And Heart Failure And Predictors For Irreparability Of Heart Function

Background:Multiple prospective randomized studies had demonstrated that cardiac resynchronization therapy(CRT)via biventricular pacing(Bi VP)could improve ventricular synchrony and result in clinical benefits in patients with heart failure and LBBB.However,a high CRT non-response rate of 30-40% were still a challenge due to the limit of different cardiac etiology,the position of left ventricular lead,and the ventricular pacing ratio.In recent years,the use of His-Purkinje system pacing(HPSP),which includes his bundle pacing(HBP)and left bundle branch pacing(LBBP),had been reported in patients with candidates for Bi VP.Furthermore,it delivered more effective ventricular resynchronization than Bi VP and reduced the incidence of pacing-related cardiomyopathy.HPSP could effectively correct left bundle branch block,then reverse true left bundle branch block associated with heart failure theoretically.However,some patients who could not fully benefit from it in practice.The potential predictors for irreparable heart function after HBP in patients with heart failure and typical LBBB correction by HBP were still unknown.Objective:The objective of our study is to assess the clinical benefits of typical LBBB correction by HPSP and identify the potential predictors for unreversal heart function after HPSP in patients with true LBBB and heart failure.Method: Patients who met the inclusion criteria were continuously enrolled from April2018 and ended in April 2020 in the first affiliated hospital of Da Lian Medical University.The inclusion criteria were as follows:(1)ECG with a morphology of typical complete LBBB that meets the Strauss criteria(2)heart failure patients with NYHA Class II–IV symptoms(LVEF<35%)after at least 3 months of optimal medical therapy,who accepted permanent HBP or LBBP.The baseline medical history(including the course of heart failure,gender,age,comorbidity,medication)was collected and 12 lead surface electrocardiograms and transthoracic echocardiography were performed before implantation.The electrocardiograms calibrated at 25 mm/s was performed to assess the QRS duration and verify mechanical resynchronization and echocardiographic indices-including left ventricular end systolic volume(LVESV),left ventricular ejection fraction(LVEF),left ventricular end diastolic dimensions(LVEDD),and left atrial dimensions(LAD),mitral and tricuspid valve regurgitation.Follow-up was done on the 1st month,6th month,12 th month,18 th month and 24 th month.We collected and evaluated His capture thresholds with LBBB correction,R-wave amplitude,pacing impedance,the percentage of HBP and lead-related complications(such as lead dislodgement,lead fracture,pneumothorax,infection,thrombosis and loss of capture)before and after implantation.The clinical outcomes included NYHA functional class,pacemaker replacement hospitalization,HF hospitalization and mortality were documented.The changes of 12-lead ECG parameters,pace-related parameters and biochemical markers of heart failure were evaluated.And the predictors of irreparable heart function were further analyzed.Result:We included 38 patients with typical LBBB and heart failure were enrolled,and35 patients accepted-among them(92.11%)were implanted permanent HBP(32,91.43%)or LBBP(3,8.57%)successfully.The mean age of all the 35 patients was 71.11± 9.66 years old,and 57.14%(20/35)of them were male.10(28.57%)patients with coronary heart disease,1(2.86%)patient with ischemic cardiomyopathy,18(51.43%)patients with a history of hypertension,11(31.43%)patients with a history of diabetes and 8(22.85%)patients with a history of atrial fibrillation.There were no deaths during the follow-up period of 16.03 ± 3.85 months.QRS duration decreased significantly(169.69 ± 20.62 ms vs 112.40 ± 19.60 ms,P<0.001).LV ejection fraction improved from26.43 ± 5.88% to 42.23 ± 11.64%(P<0.001),LVESV decreased significantly(168.10±75.69 ml vs 81.54±41.16 ml,P<0.001)and New York Heart Association functional class changed from 3.37 ± 0.55 to 2.37 ± 0.77.In addition,mitral regurgitation,tricuspid regurgitation,left atrial diameter and left ventricular end systolic diameter were also significantly improved(all with P<0.001 vs baseline).Impedance during follow-up was significantly lower than those at the time of implantation(P<0.001),however,there were no significant differences in thresholds and R-wave amplitudes.Cardiac function was normalized in 15(42.86%)patients after follow-up 8.87 ± 3.84 months.There was no statistical difference between the patients of the cardiac function recovery and the patients with predictors without the cardiac function recovery in gender,age,diseases(diabetes,hypertension,chronic kidney disease(CKD),coronary heart disease),medication(β-receptor blocker,ARNI/Angiotensin Converting Enzyme Inhibitor(ACEI)/Angiotensin II Receptor Antagonist(ARB),spironolactone and statins),preoperative QRS duration,TR,LVEDD and LAD.However,the course of heart failure was longer(5.07±2.49 y vs 6.95±2.65 y,P=0.040),the capacity of the preoperative LVESV was larger(114.42 ± 38.38 ml vs 206.00 ± 72.97 ml,P<0.001)and the postoperative QRS duration was longer(98.48 ± 12.79 ms vs 122.90 ± 17.2ms,P<0.001)were often found in patients without the cardiac function recovery.The longer QRS duration(OR=1.09,95% CI 1.01-1.18,P=0.029)after HPSP was the independent predictor for irreparable heart function after HPSP after the multivariate logistic regression analysis.Conclusions: HPSP improved LVEF and NYHA Class and decreased QRS duration in patients with typical LBBB and heart failure.Postoperative long QRS duration after HPSP was the independent predictor for irreparable heart function after HPSP.