Research On CRT Interval Optimization Of Dual-chamber Left Bundle Branch Pacing

Objectives: To investigate the viability and effectiveness of the dual-chamber left bundle branch anti-heart failure system,and to further optimize the atrial-ventricular interval(AVI)based on the right atrial sense-left bundle branch sense(RAS-LBBS)and the right atrial-right atrial(RA-RA)interval to explore and develop a new AVI automatic optimization algorithm for the dual-chamber left bundle branch anti-heart failure system.Methods: A total of 53 patients admitted to the Department of Cardiology,the First Affiliated Hospital of Kunming Medical University from April 2018 to December 2022,who met the 2016 and 2021 ESC Guidelines for cardiac resynchronization therapy(CRT)Class Ia indications and inclusion criteria,underwent CRT treatment,and provided written consent for the study were enrolled.There were 28 cases in the study group-left bundle branch pacing(LBBP)group(10 dual-chamber system and 18 triple-chamber system)and 25 cases in the control group-Biventricular pacing(Bi VP)group(1 dual-chamber system and 24 triple-chamber system).Basic information,New York Heart Association(NYHA)cardiac function grading,6-minute walking test(6MWT),NT-pro BNP,ECG and echocardiogram synchronization indexes were collected.For patients who had undergone the procedure successfully,postoperative optimization was carried out.Using the AS-VS interval set during the operation minus atrial perception compensation(ASC)(the default value is 30ms)as the baseline,the AVI was shortened or prolonged in steps of 5-15 ms each time,and the AVI corresponding to the best surface electrocardiogram shape,the narrowest QRS wave time limit,and the best cardiac color Doppler index was chosen as best AVI.Individual rate-adaptive atrioventricular delay(RAAVD)functional parameters were then adjusted for the LBBP group.Particularly,the linear regression equation between the patient’s heart rate and the PR interval according to the patient’s Holter prior to the operation was established,and the lower limit rate and the upper tracking rate corresponding to the PR interval were obtained either directly or indirectly.The PR interval of the lower limit rate,the optimized PR interval,and the PR interval of the upper tracking rate were used to determine the RAAVD parameters for the two-chamber and three-chamber left bundle branch pacing systems.The RA-RA interval,RAS-LBBS interval,and optimized AVI of the LBBP group were colleted.The optimized AVI/RA-RA and the RAS-LBBS minus optimized AVI were used to compute the single left bundle branch pacing coefficient ε and single left bundle branch pacing offset Δ,respectively.Follow-up was performed at 3,6,and 12 months,as well as every year after the first year.The evaluation of the patient’s cardiac function according to the NYHA,the 6-MWT,a standard12-lead ECG,echocardiography,pacemaker routine parameter monitoring,the presence of complications,hospitalization for heart failure,and all-cause mortality were all included in the follow-up.The statistical analysis and processing were conducted using SPSS 22.0(SPSS,Inc.,Chicago,IL,USA),and the statistical significance threshold of P-value was set as 0.05,two-tailed.Results: 1.The QRS duration of patients in the LBBP group and the Bi VP group was dramatically reduced by CRT from 167.43 ± 17.69 ms and 165.56 ± 27.06 ms before the operation to 124.68 ± 19.94 ms and 135.40 ± 10.63 ms after the operation,respectively.The QRS duration in the LBBP group was shorter than that of the Bi VP group,according to the results of the inter-group comparison(p<0.05).2.Dual-chamber pacing systems have lower operating costs(4.00 ± 0.43 vs.12.11 ± 1.20,p<0.001)and higher expected battery lives(9.56 ± 1.85 years vs.4.48 ± 0.79 years,p<0.001),but there is no statistically significant difference in operation times(2.58 ± 0.61 hours vs.3.20 ± 1.25 hours,p>0.05).3.The proportion of patients with NYHA III and above,the 6MWD,and the level of NT-pro BNP at the most recent follow-up in both groups were significantly better than baseline(p>0.05)after an average follow-up of 13.17 ± 6.77 months;echocardiography revealed that cardiac function,cardiac cavity size,and mechanical synchronization of the atrioventricular,interventricular,and left ventricular were significantly improved in relative to those in baseline.4.The mean values of RA-RA interval,RAS-LBBS interval and optimal AVI of 28 subjects in the LBBP group were 832.01±93.05 ms,180.29±44.69 ms and 124.29±23.64 ms,respectively.According to the formula,ε is caculated as 0.142 ± 0.021 and Δ is 56.00 ± 15.56 ms.An approach is proposed based on the formula for automatic AVI optimization of the dual-chamber anti-heart failure pacing system based on left bundle branch area pacing.Conclusion:1.It is feasible to realize cardiac resynchronization therapy by dynamic fusion of autoexcitation in two-chamber left bundle branch pacing;dual-chamberanti-heart failure pacing system based on left bundle branch area pacing can significantly shorten QRS duration,improve cardiac function,and mechanically synchronize the heart;the effect is comparable to standard double chamber pacing;2.For heart failure,a dual-chamber pacemaker with a single left bundle branch pacing can optimize the AVI using RA-RA and RAS-LBBS intervals.14% of the RA-RA interval or RAS-LBBS interval minus 60 ms is the optimal AVI.