Left Bundle Branch Pacing Group Research Articles

Long-term efficacy of left bundle branch pacing and biventricular pacing in patients with heart failure complicated with left bundle branch block.

Left bundle branch pacing (LBBP) can physiologically correct complete left bundle branch block (CLBBB), and has become the best alternative to biventricular pacing (BiVP). To compare the efficacy of LBBP and BiVP in patients with heart failure (HF) complicated with CLBBB. This was a single-center retrospective study. Patients with HF complicated with CLBBB who underwent successful cardiac resynchronization therapy (CRT) in Wuhan Asian Heart Hospital from June 2018 to June 2023 were enrolled and divided into LBBP group and BiVP group according to the pacing method. The primary endpoints were the absolute increase of left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), and echocardiographic response rate. Secondary endpoints were all-cause mortality, heart failure hospitalization (HFH), NT-proBNP, paced QRS duration, pacing threshold, and procedural duration. A total of 120 patients were enrolled in this study, including 60 patients in LBBP group and 60 patients in BiVP group. The median follow-up time was 37 ± 19 months. Compared with BiVP group, LBBP group had a more significant increase in absolute LVEF (ΔLVEF) (14.8 ± 9.9% vs. 10.7 ± 9.0%, P = 0.02), a more significant reduction in LVEDD (56.9 ± 10.9 mm vs. 61.1 ± 10.8 mm, P = 0.03), and a higher echocardiographic super response rate (65% vs. 45%, P = 0.02). There were no significant differences in all-cause mortality (1.7% vs. 10.0%, P = 0.11) and HFH (6.7% vs. 13.3%, P = 0.22). In terms of paced QRS duration (128.7 ± 14.1 ms vs. 137.5 ± 16.5 ms, P = 0.002), pacing threshold (0.72 ± 0.21 V/0.4 ms vs. 1.39 ± 0.51 V/0.4 ms, P < 0.001), procedural duration (134.1 ± 32.2 min vs. 147.7 ± 39.4 min, P = 0.04), the LBBP group was superior to the BiVP group. In nonischemic cardiomyopathy (NICM) patients with HF combined with CLBBB and LVEF ≤ 35%, LBBP is better than BiVP.

Is left bundle branch pacing (LBBP) associated with better depolarization and repolarization kinetics than right ventricular mid septal pacing (RVSP)? - Comparison of frontal QRS -T angle in patients with LBBP, RVSP and normal ventricular conduction

AimsTo assess the frontal QRS- T angle (f QRS- T angle) in patients with left bundle branch pacing (LBBP) as compared to right ventricular mid septal pacing (RVSP) implanted for symptomatic high degree atrioventricular (AV) block and to compare with control subjects with normal ventricular conduction (CSNVC) MethodsA total of one-fifty subjects were chosen (50 patients with LBBP, 50 patients with RVSP and 50 CSNVC). The indication for pacemaker implantation was symptomatic high degree AV block. Baseline clinical and electrocardiogram (ECG) parameters like QRS duration (QRSD), QRS axis and f QRS-T angle and Ejection Fraction (EF) were assessed. f QRS-T angle was measured as the difference between the computerised mean frontal QRS and T wave axes in the limb leads. If the difference between the QRS axis and T-wave axis exceeds 180°, then the resultant QRS-T angle would be calculated as 360° minus the absolute angle to obtain a value between 0° and 180°. Baseline, immediate post procedural and 6 month follow up (f/u) ECGs and EF were chosen for the analysis. ResultsPatients who underwent LBBP had significantly shorter paced QRSD than patients who had undergone RVSP (112 ± 12 ms vs 146 ± 13 ms; 95 % confidence interval (CI): 43, −31; p<0.001). There was no significant difference in the QRSD before and after LBBP. The QRSD before and after pacing in RVSP was 111 ± 27 ms and 146 ± 13 ms; 95 % CI: 43, −28; p < 0.001. The QRSD in control patients with NVC was 82.94 ± 9.59 ms.RVSP was associated with wider f QRS-T angle when compared with LBBP (103 ± 53° vs 82 ± 43°; 95 % CI: 39, −1.0; p = 0.037). The baseline and immediate post procedure f QRS-T angle in LBBP was 70 ± 48° and 82 ± 43°; 95 % CI: 31, 5.3; p = 0.2. At 6 months f/u, the f QRS-T angle was 61 ± 43°; 95 % CI: 8.5, 35; p=0.002. The baseline and immediate post procedure f QRS-T angle in RVSP was 67 ± 51° and 103 ± 53°; 95 % CI: 54, −17; p < 0.001. At 6 months f/u, the f QRS-T angle in RVSP group was 87 ± 58°; 95 % CI: 2.6, 29; p = 0.020. The f QRS T angle in control patients with NVC was 24 ± 16°. When subgroup analysis was done the difference in the f QRS-T angle was significant between RVSP and LBBP groups only in patients who had wide QRS escape.The mean LVEF at 6-month follow-up in LBBP vs RVSP was 61 ± 3.7 % vs 57.1 ± 7.8 %; 95 % CI:1.48, 6.32, p = 0.002. In the RVSP group, three patients developed pacing induced cardiomyopathy (PIC) whereas no patients in the LBBP group developed PIC at 6-month follow-up; p=0.021. One patient with PIC had deterioration of functional status with new onset HF symptoms. The patient symptoms improved with medical therapy and needed no hospitalisation. The patient declined further interventions including upgradation to CRT or LBB pacing. No deaths or ventricular arrhythmias were observed during the study period. ConclusionLBBP is associated with narrower f QRS-T angle as compared to RVSP both at post implant period and at 6 month f/u period. These findings might be due to the more physiological depolarization and repolarization kinetics associated with LBBP. RVSP was associated with 6 % incidence of PIC. Hence wide f QRS-T angle might be a predictor of PIC.

Left Bundle Branch Pacing vs Left Ventricular Septal Pacing vs Biventricular Pacing for Cardiac Resynchronization Therapy

BackgroundLeft bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are considered to be acceptable as LBBAP strategies. Differences in clinical outcomes between LBBP and LVSP are yet to be determined. ObjectivesThe purpose of this study was to compare the outcomes of LBBP vs LVSP vs BIVP for CRT. MethodsIn this prospective multicenter observational study, LBBP was compared with LVSP and BIVP in patients undergoing CRT. The primary composite outcome was freedom from heart failure (HF)–related hospitalization and all-cause mortality. Secondary outcomes included individual components of the primary outcome, postprocedural NYHA functional class, and electrocardiographic and echocardiographic parameters. ResultsA total of 415 patients were included (LBBP: n = 141; LVSP: n = 31; BIVP: n = 243), with a median follow-up of 399 days (Q1-Q3: 249.5-554.8 days). Freedom from the primary composite outcomes was 76.6% in the LBBP group and 48.4% in the LVSP group (HR: 1.37; 95% CI: 1.143-1.649; P = 0.001), driven by a 31.4% absolute increase in freedom from HF-related hospitalizations (83% vs 51.6%; HR: 3.55; 95% CI: 1.856-6.791; P < 0.001) without differences in all-cause mortality. LBBP was also associated with a higher freedom from the primary composite outcome compared with BIVP (HR: 1.43; 95% CI: 1.175-1.730; P < 0.001), with no difference between LVSP and BIVP. ConclusionsIn patients undergoing CRT, LBBP was associated with improved outcomes compared with LVSP and BIVP, while outcomes between BIVP and LVSP are similar.

Feasibility study on cardiac resynchronization in the treatment of heart failure by single left bundle branch pacing

To examine the feasibility of single left bundle branch pacing for cardiac resynchronization therapy (CRT) by carrying out a frequency adaptive atrioventricular delay (RAAVD) algorithm and automatic optimization of the single left bundle branch pacing atrioventricular interval (AVI) based on the right atrioventricular interval (RAS–RVS). Thirty-six patients with CRT class Ia indications according to the European Society of Cardiology 2016 guidelines and implanted with RAAVD functional three-chamber pacemakers were prospectively enrolled in this study. Patients were divided into a single left bundle branch pacing group (n = 21) and a standard biventricular pacing group (n = 15). The optimization of the two groups was performed under standard cardiac colour Doppler ultrasound, followed by the comparison of the QRS width, cardiac function improvement, and echocardiography indicators. The ratio of AVI to the right atrial-right ventricular interval (RAS–RVS) after single LV pacing optimization was defined as the single left bundle branch pacing coefficient (LUBBPε). In comparison to the BVP, the QRS was significantly narrowed (P = 0.017), accompanied by a significantly increased proportion of patients with NYHA class I and II, as well as the 6MWT. Compared with standard biventricular pacing, LVEDD was significantly shortened (P = 0.045), accompanied by significantly improved LAD, AVVTI, EA distance/RR, IVMD, and TS-SD after the operation. RAS–RVS was 156 ± 33 ms, the optimized AVI was 102 ± 10 ms, and LUBBPε was calculated to be 0.66 ± 0.06. Depending on the LUBBPε, a three-chamber pacemaker with a single left bundle branch pacing system was developed based on RAS–RVS-optimized AVI automatically. A three-chamber pacemaker with single left bundle branch pacing can achieve CRT based on RAS–RVS, reaching the optimal AVI of 66% of RAS–RVS.

Outcomes of Upgrading to LBBP in CRT Nonresponders: A Prospective, Multicenter, Nonrandomized, Case-Control Study

BackgroundCardiac resynchronization therapy (CRT) nonresponders account for nearly 30% of CRT candidates. Left-bundle branch pacing (LBBP) is an alternative to CRT. ObjectivesThis study aimed to evaluate the feasibility, clinical efficacy, and outcomes of upgrading to LBBP in CRT nonresponders, using propensity-score matching (PSM) analysis. MethodsCRT nonresponders were defined as those with an implantable CRT-pacemaker or CRT-defibrillator for more than 12 months who remained nonresponsive (a decrease in left ventricular end-systolic volume of <15% or a left ventricular ejection fraction [LVEF] absolute increase of <5%) after optimal medical therapy and device optimization compared with baseline. In total, 145 CRT nonresponders were prospectively enrolled and randomly divided into 2 groups: upgraded to LBBP (n = 48), and continuing biventricular pacing (BVP) (control; n = 97). PSM was performed at a 1:1 ratio, and clinical evaluation and echocardiographic assessments were compared at baseline and follow-up in paired cohorts. The primary composite endpoint for clinical outcomes (heart failure-related rehospitalization events, all-cause death, or heart transplantation) was analyzed. ResultsSuccessful upgrading to LBBP was achieved in 48/49 patients (97.96%), with a significant decrease in QRS duration (P < 0.001). In the paired LBBP group, LVEF significantly increased (baseline: 29.75% ± 7.79%; 6 months: 37.78% ± 9.25% [P < 0.001]; 12 months: 38.84% ± 12.13% [P < 0.001]) with 21/44 patients (47.73%) classified as echocardiographically responsive, whereas in the BVP control group, no significant improvement was observed (29.55% ± 6.74% vs 29.22% ± 8.10%; P = 0.840). In a multivariate logistic regression model, LV end-diastolic volume and baseline LBBB QRS morphology were independent predictors of echocardiographic response after upgrading to LBBP. At a median 24 months, the primary composite endpoint was significantly lower in the LBBP group (HR: 0.31; 95% CI: 0.14-0.72; log-rank P = 0.007). ConclusionsUpgrading to LBBP is feasible and effective in achieving significant heart function improvement and better clinical outcomes in CRT nonresponders, making it a reasonable and promising pacing strategy. (LBBP in CRT Non-Response patients; ChiCTR1900028131)

Left bundle branch pacing preserved left ventricular myocardial work in patients with bradycardia.

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. Left ventricular (LV) myocardial work (MW) incorporates afterload and LV global longitudinal strain to estimate global and segmental myocardial contractility. However, the effect of LBBP on LV MW remains unknown. This study aimed to evaluate the impact of LBBP on LV MW in patients receiving pacemaker for bradyarrhythmia. We prospectively enrolled 70 bradycardia patients with normal LV systolic function receiving LBBP (n = 46) and non-selective His-bundle pacing (NS-HBP) (n = 24). For comparative analysis, patients receiving right ventricular pacing (RVP) (n = 16) and control subjects (n = 10) were enrolled. Two-dimensional speckle tracking echocardiography was performed. The LV pressure-strain loop was non-invasively constructed to assess global LV MW. After 6-month follow-up, LBBP group (with >40% ventricular pacing during 6 months) had shorter peak strain dispersion (PSD) compared with RVP group, and higher LV global longitudinal strain compared with RVP group and NS-HBP group, but had no difference in left intraventricular mechanical dyssynchrony, including septal-to-posterior wall motion delay and PSD, compared with NS-HBP group. During ventricular pacing, LBBP group had higher global MW index (GWI) (2,189 ± 527 vs. 1,493 ± 799 mmHg%, P = 0.002), higher global constructive work (GCW) (2,921 ± 771 vs. 2,203 ± 866 mmHg%, P = 0.009), lower global wasted work (GWW) (211 ± 161 vs. 484 ± 281 mmHg%, P < 0.001) and higher global MW efficiency (GWE) (91.4 ± 5.0 vs. 80.9 ± 8.3%, P < 0.001) compared with RVP group, and had lower GWW (211 ± 161 vs. 406 ± 234 mmHg%, P < 0.001) and higher GWE (91.4 ± 5.0 vs. 86.4 ± 8.1%, P < 0.001) compared with NS-HBP group. In this study we found that in patients with mid-term (6-month) high ventricular pacing burden (>40%), LBBP preserved more LV MW compared with NS-HBP and RVP. Further studies are warranted to assess the association between LV MW and long-term clinical outcomes in LBBP with high ventricular pacing burden.

Acute procedural comparison between left bundle branch pacing and left ventricular septal pacing

Abstract Funding Acknowledgements Type of funding sources: None. Background Left bundle branch area pacing (LBBAP) includes both left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP). The implant procedure characteristics of these two pacing modalities have not been yet fully described. We sought to compare 2 different LBBAP implant strategies: the first one accepting LVSP as a procedure endpoint and the second one aiming at achieving LBBP in every patient. Methods Consecutive patients undergoing LBBAP at our centre from January 2020 to October 2022 were included. After our initial LBBAP learning curve, LVSP was accepted as a procedure endpoint in the first 217 patients. Thereafter, LBBP was attempted in every patient with a maximum of 5 lead deployment attempts or &amp;gt; 30 minutes for lead implant even if LVSP had been previously achieved. Definition of LBBP or LVSP was established according to currently accepted criteria. Procedure characteristics including total procedure time, LBBAP lead implant time, radiation exposure parameters, electrical parameters and acute complications were evaluated. Results A total of 422 consecutive patients were included in the analysis (217 patients with LVSP as acceptable endpoint, and 205 patients with LBBP as final endpoint). Baseline characteristics of the patients are described in table 1. In the LVSP group, the final capture pattern was LVSP in 57.6% and LBBP in 29% whereas in the LBBP group the final capture pattern was LVSP in 19.5% and LBBP in 71.2%. Failure of LBBAP occurred in 13.4% of LVSP group and 9.3% of LBBP group. LBBAP lead position in the septum was basal in 12,5% of LVSP group vs. 23,9% of LBBP group and medium in 81.7% and 72%, respectively (Table 2). A discrete LB potential was identified in 21.2% of LVSP group patients and in 45.8% of LBBP patients, p&amp;lt;0.0001. The LBBP strategy was associated with significantly longer LBBAP lead implant time (19±11min vs. 17±10 min, p=0.05), higher number of lead deployment attempts (3.4±1.8 vs 2.9±1.9, p=0.004), higher number of lead turns (22.4±4.3 vs. 18.3±4,1, p&amp;lt;0,0001) and higher fluoroscopy time (13.2±9.5 min vs. 10.6±9.3 min, p=0.003). Incidence of septal perforation was comparable between the 2 groups (10.6% for LVSP group and 7.8% for LBBP group, p=0.4) but development of complete AV block during implant tended to be more frequent in LBBP group (3.9% vs. 1.4%, p=0.13). The final paced QRS width, measured from the pacing spike, was comparable between the 2 groups: 161±18 ms for LVSP group and 158±19 ms for LBBP group, p=0.2. Conclusions LBBP can be achieved in more than 70% of unselected patients with significantly prolonged procedure time, higher number of lead deployment attempts and higher radiation exposure. When LVSP is accepted as an outcome, LBBP can be achieved in up to 29% of cases. The final paced QRS duration is comparable between the two implant strategies. Any potential clinical benefit of LBBP over LVSP in the long-term remains to be proven.

Left bundle brunch pacing versus conventional right ventricular pacing in patients with bradycardia and conduction system disorders: a systematic review and meta-analysis

Abstract Funding Acknowledgements Type of funding sources: None. Background Right Ventricular Pacing (RVP) is well established as the widely accepted pacing method. However, its effects in ventricular function can be detrimental, causing electrical and mechanical dysynchrony and potential LVEF impairment. Left Bundle Branch Pacing (LBBP) is a new pacing strategy that appears to have better results preserving left ventricular function, by directly engaging the intrinsic conduction pathway of the heart. Purpose The aim of this systematic review and meta-analysis is to compare the safety and efficacy of the two pacing methods (LBBP and RVP) in patients suffering from bradyarrhythmia and conduction system disorders. Methods Medline, Embase and Pubmed databases were searched for studies comparing LBBP with RVP. Outcomes were QRSd (QRS duration), ventricular mechanical synchrony, LVEF changes, and Heart Failure Hospitalizations (HFH) to assess the efficacy, lead properties and complications to assess the safety. Two independent reviewers identified studies, extracted data, and assessed the risk of bias using the Cochrane Risk of Bias 2 tool for randomized clinical trials and the Newcastle-Ottawa-Scale for observational studies. Pairwise meta-analysis was conducted using random and fixed effects models. Risk Ratios (RRs) and weighted and standard mean difference (WMD, SMD) with 95% confidence intervals (CIs) were used to report dichotomous and continuous variables respectively. Heterogeneity was assessed with the I² statistic. Results 1318 articles were identified, and finally 25 trials with 4250 patients (2127 LBBP and 2123 RVP) were included in the analysis. Pooled analyses verified that QRSd is shorter in LBBP group both at implantation (WMD:-32.32, CI 95%:-35.18 to -29.45; I²=88%; P&amp;lt;.001) and at Follow Up (WMD: -32.20, CI 95%: -40.70 to -23.71; I²=92%; P&amp;lt;.001) and LBBP succeeded better interventricular mechanical synchrony (SMD:-2.04, CI 95%:-2.32 to -1.76; I²=21%; P&amp;lt;.001) than RVP. Intraventricular mechanical synchrony was also significantly better in LBBP vs RVP independently of the way of measurement in each study (SMD:-1.77, CI 95%:-2.45 to -1.09; I²=90%; P&amp;lt;.001) and in the subgroup analysis of the studies that implemented the same way of measurement (P&amp;lt;.001; I²=26%). LVEF alteration was not significant in the LBBP compared to native (P=.68; I²=52%), while in the RVP group showed a significant reduction (P&amp;lt;.001; I²=51%). LBBP showed, significantly better results in HFH (P&amp;lt;.001; I²=0%) and achieved similar pacing thresholds (P=.86) and higher R wave amplitudes (P&amp;lt;.05) than RVP while lead related complications had no difference between the two groups (LBBP=1.90% vs RVP=1.72%; P=0.71). Conclusions To our knowledge this is the first meta-analysis that assess the safety and efficacy of LBBP in such an important number of patients. LBBP preserves ventricular electrical and mechanical synchrony, shows a reduction in HFH compared to RVP and has excellent pacing parameters, without compromising safety.

Incidence of conversion to sinus rhythm in refractory atrial fibrillation patients after atrioventricular node ablation with conduction system pacing

Abstract Funding Acknowledgements Type of funding sources: None. Background "Ablate and pace" strategy is a reasonable therapeutic option in refractory atrial fibrillation (AF) when rhythm or rate control cannot be achieved with catheter ablation or pharmacological therapy. Atrioventricular node ablation (AVNA) combined with conduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch pacing (LBBP), are increasingly adopted, as they offer more physiological activation of the left ventricle compared to other pacing modalities. However, the incidence of conversion to sinus rhythm after "ablate and pace" strategy with CSP is not known. Purpose To determine the incidence of spontaneous conversion to sinus rhythm and its predicting factors in patients undergoing AVNA and CSP. Methods Refractory AF patients undergoing AVNA with CSP at our institution between June 2018 and May 2022 were prospectively included. Echocardiographic and clinical parameters including ECG were assessed at baseline and 6 months after the procedure. Results Sixty-three patients (male 41.3%, age 71±9 years, left ventricle ejection fraction (LVEF) 40% (IQR 20)) were included. Thirty-seven patients (58.7%) received HBP and 26 patients (41.3%) LBBP. During follow-up, spontaneous conversion to sinus rhythm (SR) was registered in 5 patients (8%); 3 in HBP group and 2 in LBBP group. Baseline characteristics of patients who converted to SR did not differ from non-sinus rhythm (NSR) patients except for left atrial volume index (LAVI), which was smaller in SR group (43 mL/m2 (IQR 6) vs. 60 mL/m2 (IQR 19); p&amp;lt;0.01). Multiple regression model confirmed an inverse association between LAVI and conversion to sinus rhythm even after considering other clinically relevant covariates (odds ratio=0.685, p=0.03). At follow-up, LAVI did not change in any group (SR: p=0.345; NSR: p=0.508). LVEF increased in both groups, from 40% (IQR 20) to 51% (IQR 18) in NSR group (p&amp;lt;0.01) and from 41% (IQR 11) to 54% (IQR 11) in SR group (p=0.138), although the increase in SR group did not reach statistical significance due to small sample size. Similarly, ESVi decreased in both groups; in NSR group (from 47 mL/m2 (IQR 33) to 29 mL/m2 (IQR 24), p&amp;lt;0.01) and in SR group (from 33 mL/m2 (IQR 19) to 25 mL/m2 (IQR 0), p=0.176), where statistical significance was not reached due to small sample size and small initial volumes. Symptomatic improvement according to NYHA class was more pronounced in SR group (p=0.026). Conclusion The results of our study show that spontaneous conversion to sinus rhythm after AVNA combined with CSP is not uncommon, especially in patients with smaller left atria. Patients who converted to SR showed superior symptomatic improvement compared to NSR patients. Larger studies are warranted to clarify the predicting variables of SR restoration in these patients, which should be considered for initial atrial pacing lead implantation (dual-chamber device) when "ablate and pace" strategy is adopted.

Autocapture algorithm behaviour in left bundle branch pacing

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Autocapture algorithms allow remote monitoring of patients, reducing the need for face-to-face hospital consultations and increasing patient safety. These algorithms are widely validated in patients with conventional pacing and are not recommended in His bundle pacing, but there is no information on its behaviour in left bundle branch pacing (LBBP). Purpose The objective was to analyse the autocapture algorithm behaviour in LBBP and its differences with conventional pacing and manual thresholds during device first programming (acute phase), after 1-7 days (subacute phase) and 1-3 months later (chronic phase). Methods Prospective non-randomised single-centre comparative study. Consecutive patients with an indication for cardiac pacing were included. The implant was performed in the left bundle branch area or in the right ventricle endocardium (outflow tract or apex) at the discretion of the operator. LBBP was considered according to published criteria. Autocapture algorithm was activated in both groups whenever allowed by the device. The thresholds manual measurement was performed with the intracavitary electrogram and the surface electrocardiogram. Results Sixty patients were included, 40 with LBBP and 20 with conventional pacing. Baseline characteristics of patients are shown in Figure 1. The feasibility of the autocapture algorithm was more frequent in late phases, with a favourable trend toward bipolar pacing (Figure 2A). The failures in the activation of the algorithm were mainly due to the absence of adequate safety margins (90.9% in conventional pacing and 86.6% in LBBP), the rest were attributable to atrial tachyarrhythmias (9.1 and 6.7%, respectively) and electrical noise (remaining 6.7% in LBBP). In LBBP group, there were not statistically significant differences between manual and automatic thresholds except in subacute phase (unipolar) (Figure 2B), and both remained stable during follow-up (average increase of 0.46V). Conclusions Autocapture algorithm is feasible in LBBP, with a favourable trend toward bipolar pacing. Automatic thresholds are similar to manual in patients with LBBP, and they remain stable during follow-up.

Echocardiographic Evaluation of the Effect on Left Ventricular Function Between Left Bundle Branch Pacing and Right Ventricular Pacing.

The purpose of this study was to assess the left ventricular function effects of permanent left bundle branch pacing (LBBP) versus traditional right ventricular pacing (RVP). Consecutive patients receiving pacemaker implantation were included and divided into left bundle branch block (LBBB) group and right ventricular pacing (RVP) group. Baseline characteristics were collected, and they received 1-year follow-up. Electrocardiogram (ECG) characteristics and pacing parameters were assessed before and after implantation. Cardiac function parameters such as left ventricular ejection fraction (LVEF) and tricuspid regurgitation (TR) were recorded and compared. Of 78 patients included, 45 patients received LBBP (mean age, 72.7 ± 12.2 years; male, 55.6%) and 33 patients underwent RVP (mean age 72.9 ± 11.8 years; male, 63.6%). The pacing parameters were satisfactory during the implantation and remained stable during mid-term follow-up. During the follow-up period, LBBP patients had a greater decrease in LVEDD and LVESD. The TR in the LBBP group was significantly improved as compared to the RVP group (P=0.016). Permanent LBBP achieves favorable cardiac hemodynamic effects with good stability and safety. LBBP may reduce severe TR at 1-year follow-up, and LBBP may be an option for patients with severe TR.

Left bundle branch pacing on mechanical synchrony and myocardial work in bradycardia patients.

Left bundle branch pacing (LBBP) has emerged as a novel physiological pacing method to produce narrower QRS duration, but whether it could restore mechanical synchrony and improve myocardial work still lacks sufficient evidence. Therefore, the goal of this study was to evaluate mechanical synchrony and myocardial work in LBBP. We collected 20 patients with LBBP due to symptomatic bradycardia and another 29 age-matched patients with right ventricular pacing (RVP). For LBBP patients, cardiac electro-mechanical synchrony and myocardial work were measured at baseline and 7 days after implantation and compared with the RVP patients. In the LBBP group, paced QRS duration and mechanical synchrony were not significantly different from baseline(all P > 0.05), but significantly smaller than that in the RVP group (all P<0.05). Meanwhile, global longitudinal strain (GLS) in LBBP was greater than that in the RVP group (17.7 ± 3.5% vs. 14.8 ± 3.1%, P < 0.05). Global myocardial work index and global constructive work were also better than that in the RVP group(all P<0.05). Global work efficiency was 91.9 ± 3.1%, which was greater when compared with RVP (P < 0.05). LBBP provides better cardiac electro-mechanical synchrony and more effective myocardial work than that in RVP, thus improving global heart function.

Global left ventricular myocardial work efficiency in left bundle branch pacing versus right ventricular septal pacing: preliminary results of a randomized trial

Abstract Background Recently, the concept of left bundle branch pacing (LBBP) has emerged in clinical practice, in an attempt to prevent the deteriorating effects of right ventricular pacing (Vp). Purpose The aim of this study is to compare the effect of Vp on left ventricular (LV) dyssynchrony in patients with atrioventricular block (AVB) and preserved ejection fraction (EF), subjected to either LBBP or right ventricular septal pacing (RVSP). Methods Patients with AVB are randomized 1:1 to LBBP or RVSP. The effect of Vp is evaluated by echocardiographic indices of dyssynchrony, such as global myocardial work efficiency (GWE) and peak systolic dispersion (PSD). GWE represents the ratio of constructive work divided by the sum of constructive and wasted work [1]. Successful LBBP is defined by the presence of right bundle branch block paced QRS morphology in lead V1 and stim to LV activation time &amp;lt;75 msec [2]. No back-up right Vp lead was used in LBBP group. Results We conducted a preliminary analysis of the first 20 patients. Enrollment is still ongoing and total follow-up period is one year. We sought to investigate the acute effect of Vp on LV dyssynchrony 24 hours post procedure. Patients' baseline characteristics were similar in both groups and are presented in Table 1. One crossover was noted from LBBP to RVSP group, due to high ventricular capture threshold during implant. Implantation time was increased in LBBP arm (130±17.4 min in LBBP versus 47.7±4.5 min in RVSP group, p=0.004). Left bundle branch potential was recorded in 3 out of 10 LBBP patients. No statistically significant difference was demonstrated in GWE between the two groups (91.3% in LBBP versus 87.4% in RVSP group, p=0.052). PSD was numerically shorter in LBBP (53.3 msec) versus in RVSP (63.6 msec), p=0.114. There were no complications during both the acute perioperative phase and the running period of the follow-up. Moreover, no acute ventricular threshold capture rise, or lead dislodgement has been observed in neither group. The increased implantation time may be attributed to the more demanding technique, or the learning curve period required in the arm of LBBP. In the present analysis, a remarkable difference regarding GWE in favor of the LBBP group was demonstrated, although statistically not significant. However, even in this initial phase of the study, there is a trend of better LV synchrony and less wasted myocardial work in the LBBP group. The final difference of these indices will be assessed at the end of the one-year follow-up, when comparative results will be available. Conclusion LBBP is a novel, safe pacing method. Despite the longer procedural time and the risk of crossover, LBBP seems to offer better – without however statistical significance – LV synchrony even in the acute postoperative phase compared to RVSP. Longer follow-up studies are required to test whether LBBP compared to RVSP confers substantial clinical benefit. Funding Acknowledgement Type of funding sources: None.

Impact on right ventricular performance in patients undergoing permanent pacemaker implantation: Left bundle branch pacing versus right ventricular septum pacing.

The novel method of left bundle branch pacing (LBBP) has been reported to achieve better electrical and mechanical synchrony in the left ventricle than conventional right ventricular pacing (RVP). However, its effects on right ventricle (RV) performance are still unknown. Consecutive patients undergoing dual-chamber pacemaker (PM) implantation for sick sinus syndrome (SSS) with normal cardiac function and a narrow QRS complex were recruited for the study. The pacing characteristics and echocardiogram parameters were measured to evaluate RV function, interventricular and RV synchrony, and were compared between ventricular pacing-on and native-conduction modes. A total of 84 patients diagnosed with SSS and an indication for pacing therapy were enrolled. Forty-two patients (50%; mean age 65.50 ± 9.30 years; 35% male) underwent successful LBBP and 42 patients (50%; mean age 69.26 ± 10.08 years; 33% male) RVSP, respectively. Baseline characteristics were similar between the two groups. We found no significant differences in RV function [RV-FAC (Fractional Area Change)%, 47.13 ± 5.69 versus 48.60 ± 5.83, p = .069; Endo-GLS (Global Longitudinal Strain)%, -28.88 ± 4.94 versus -29.82 ± 5.35, p = .114; Myo-GLS%, -25.72 ± 4.75 versus -25.72 ± 5.21, p = .559; Free Wall St%, 27.40 ± 8.03 versus -28.71 ± 7.34, p = .304] between the native-conduction and LBBP capture modes, while the RVSP capture mode was associated with a significant reduction in the above parameters compared with the native-conduction mode (p < .0001). The interventricular synchrony in the LBBP group was also superior to the RVSP group significantly. LBBP is a pacing technique that seems to associate with a positive and protective impact on RV performance.

Left Bundle Branch Pacing Postatrioventricular Junction Ablation for Atrial Fibrillation: Propensity Score Matching With His Bundle Pacing.

Left bundle branch pacing (LBBP) has emerged as a promising pacing modality to preserve physiological left ventricular activation; however, prospective data evaluating its long-term safety and efficacy in pacemaker-dependent patients following atrioventricular junction (AVJ) ablation are lacking. This study aimed to examine the feasibility, safety, and efficacy of LBBP in patients with atrial fibrillation and heart failure (HF) after AVJ ablation and compare LBBP with His bundle pacing (HBP) through a propensity score (PS) matching analysis. We prospectively enrolled patients with atrial fibrillation and HF referred for AVJ ablation and LBBP between July 2017 and December 2019. The control group was patients selected from HBP implants performed from 2012 to 2019 using PS matching with a 1:1 ratio. A total of 99 patients were enrolled in the study. The LBBP implant success rate was 100%. Left ventricular ejection fraction improved from baseline 30.3±4.9 to 1-year 47.3±14.5 in HF patients with reduced ejection fraction and from baseline 56.3±12.1 to 1-year 62.3±9.1 in HF patients with preserved ejection fraction (both P<0.001), and left ventricular ejection fraction in both groups remained stable for up to 3 years of follow-up. A threshold increase >2 V at 0.5 ms occurred in only one patient. Of 176 (81.9%) of 215 patients who received permanent HBP post-AVJ ablation, 86 were matched to the LBBP group by 1:1 PS (propensity score matched His bundle pacing, N=86; propensity score matched left bundle branch pacing, N=86). No significant differences in echocardiographic or clinical outcomes were observed between the 2 groups (P>0.05), whereas lower thresholds, greater sensed R-wave amplitudes, and fewer complications were observed in the propensity score matched left bundle branch pacing group (P<0.05). LBBP is feasible, safe, and effective in patients with atrial fibrillation and HF post-AVJ ablation and has similar clinical benefits, a higher implant success rate, better pacing parameters, and fewer complications compared with HBP.

Mobile Cardiac Acoustic Monitoring System to Evaluate Left Ventricular Systolic Function in Pacemaker Patients.

The mobile cardiac acoustic monitoring system is a promising tool to enable detection and assist the diagnosis of left ventricular systolic dysfunction (LVSD). The objective of the study was to evaluate the diagnostic value of electromechanical activation time (EMAT), an important cardiac acoustic biomarker, in quantifying LVSD among left bundle branch pacing (LBBP) and right ventricular apical pacing (RVAP) patients using a mobile acoustic cardiography monitoring system. In this prospective single-center observational study, pacemaker-dependent patients were consecutively enrolled. EMAT, the time from the start of the pacing QRS wave to first heart sound (S1) peak; left ventricular systolic time (LVST), the time from S1 peak to S2 peak; and ECG were recorded simultaneously by the mobile cardiac acoustic monitoring system. LVEF was measured by echocardiography. A logistic regression model was applied to evaluate the association between EMAT and reduced EF (LVEF < 50%). A total of 105 pacemaker-dependent patients participated. The RVAP group (n = 58) displayed a significantly higher EMAT than the LBBP group (n = 47) (150.95 ± 19.46 vs. 108.23 ± 12.26 ms, p < 0.001). Pearson correlation analysis revealed a statistically significant negative correlation between EMAT and LVEF (p < 0.001). Survival analysis showed the sensitivity and specificity of detecting LVEF to be < 50% when EMAT ≥ 151 ms were 96.00% and 96.97% in the RVAP group. In LBBP patients, the sensitivity and specificity of using EMAT ≥ 110 ms as the cutoff value for the detection of LVEF < 50% were 75.00% and 100.00%. There was no significant difference in LVST with or without LVSD in the RVAP group (p = 0.823) and LBBP group (p = 0.086). Compared to LVST, EMAT was more helpful to identify LVSD in pacemaker-dependent patients. The cutoff point of EMAT for diagnosing LVEF < 50% differed regarding the pacing type. Therefore, the mobile cardiac acoustic monitoring system can be used to identify the progress of LVSD in pacemaker patients.

Effect of left bundle branch pacing on left ventricular systolic function and synchronization in patients with third-degree atrioventricular block, assessment by 3- dimensional speckle tracking echocardiography

ObjectiveTo explore the effect of left bundle branch pacing (LBBP) on left ventricular systolic function and synchronization in patients with third-degree atrioventricular block. MethodsFifty patients with third-degree atrioventricular block from 2019‐ to 01-01 to 2019-6-31 in The Affiliated Hospital of Qingdao University who were eligible for pacing indications were selected. According to different pacing locations, they were randomly divided into LBBP group and right ventricular septal pacing (RVSP) group. Three-dimensional speckle tracking technology was used to collect left ventricular global longitudinal strain (GLS), global radial strain (GRS), and global circumferential strain (GCS) before surgery, 6 months after surgery, 12 months after surgery, and 18 months after surgery. At the same time, the percentage of the standard deviation of the time when the left ventricular 16 segments reach the minimum systolic volume in the cardiac cycle (Tmsv16-SD/R-R) was calculated. And the QRS duration of the two groups was followed up. Results1. GLS in LBBP group and RVSP group after surgery was significantly higher than that before surgery. And GLS in LBBP group and RVSP group showed an upward trend after surgery. However, the increase rate in LBBP group was higher than that in RVSP group. At 18 months after surgery, LBBP group was significantly higher than that in RVSP [(29.92±4.73) vs (26.48±3.80), p<0.05]. GCS in LBBP group increased gradually after surgery. GCS in RVSP group was no significant change after surgery. At 18 months after surgery, GCS in RVSP group was significantly lower than that in LBBP group [(27.92±3.37) vs (29.48±4.40), p<0.05]. There was no significant change in GRS between the two groups(p＞0.05). 2. Tmsv16-SD/R-R in LBBP group and RVSP group after surgery were lower than that before surgery (p<0.05). Tmsv16-SD/R-R in the LBBP group after surgery remained stable (P>0.05). At 18 months after surgery, Tmsv16-SD/R-R was significantly lower than that in the RVSP group [(4.27±0.67) vs (6.34±1.70), P<0.05]. 3. The QRS duration in LBBP group after surgery was significantly lower than that before surgery. And the QRS duration of the patients in the LBBP group remained stable during the 18-month follow-up (P>0.05). The QRS duration in the RVSP group after surgery had no significant change compared with that before surgery.The QRS duration in the LBBP group was significantly lower than that in the RVSP group after surgery (P＜0.05). 4. The LVEF of the LBBP group and the RVSP group remained stable after surgery, and there was no statistical difference between the two groups. ConclusionsAs an emerging pacing method, LBBP has good postoperative contractility and can maintain good electromechanical synchronization.

Initial clinical experience of left bundle branch pacing after transcatheter aortic valve implantation

Objective: To investigate the efficacy and safety of left bundle branch pacing(LBBP) in patients after transcatheter aortic valve implantation (TAVI). Methods: This is a retrospective study. A total of 35 patients underwent TAVI and received pacemaker implantation from January 2018 to December 2020 in Beijing Fuwai Hospital were enrolled. Patients were divided into LBBP group (n=12) and right ventricular apex pacing (RVAP) group (n=23) according to the pacing position. The success rate of operation in LBBP group was calculated, and the occurrence of complications were observed, and the parameters of pacemaker were measured on the 3rd day and 1, 3 and 6 months after operation. The N-terminal pro-B-type natriuretic peptide (NT-proBNP), echocardiographic and ECG indexes were compared between the two groups on the 3rd day and 1, 3, and 6 months after pacemaker implantation. Result: A total of 35 patients were included, The age was (76.4±7.7) years, including 19 males (54.3%). The procedure time ((86.58±17.10)min vs. (68.74±9.18)min, P<0.001) and fluoroscopy duration ((20.08±4.44)min vs. (17.00±2.26)min, P<0.001) were significantly longer in LBBP group compared with RVAP group. The operation success rate of LBBP group was 11/12. There was no serious operation related complications such as pneumothorax, hemothorax, electrode dislocation, infection, and lower limb bleeding. The patients were followed up for 7.43 (5.21, 9.84) months. The programmed parameters of pacemaker were in the ideal range and stable during follow-up. At 3 and 6 months after operation, the left ventricular ejection fraction in LBBP group was higher than that in RVAP Group (at 3 months: (60.75±2.89)% vs. (57.35±3.33)%, P=0.004; at 6 months: (63.17±3.33)% vs. (56.17±3.97)%, P<0.001), NT-proBNP values was lower in LBBP group than that in RVAP Group (at 3 months: 822 (607, 1 150)ng/L vs. 1 052 (902, 1 536)ng/L, P=0.006; at 6 months: 440 (330,679)ng/L vs. 783 (588, 1 023)ng/L, P=0.001). At 1, 3 and 6 months after operation, the QRS duration was shorter in LBBP group than that in RVAP group (1 month: 99 (97, 107)ms vs. 126(124, 130)ms, P<0.001; 3 months: 98(96, 105)ms vs. 129(128, 133)ms, P<0.001; 6 months: 96(94, 104)ms vs. 130(128, 132)ms, P<0.001). Conclusions: For patients with permanent pacemaker indications after TAVI, LBBP is feasible, safe and reliable. It could improve the cardiac function in the short term, the long-term effect of LBBP needs to be further observed.

Is the pacing site closer to the left ventricular septal endocardium in left bundle branch pacing or in left ventricular septal pacing?

Distinguishing between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) is challenging. This study aimed to compare the echocardiographic distance from the pacing lead tip to the left ventricular (LV) septal endocardium between patients who underwent LBBP and those who underwent LVSP successfully. Fifty-nine consecutive patients (age 71.9 ± 12.0years, 35.6% male) with traditional indications for permanent cardiac pacing were included (LBBP group, n = 46; LVSP group, n = 13). Unipolar pacing from the final pacing sites generated narrow QRS complexes with a right bundle branch block pattern in all patients. After the procedure, a physician blinded to the group allocation performed echocardiographic measurements of the distance between the lead tip and the LV septal endocardium. The mean paced QRS duration was comparable between the LBBP group and the LVSP group (105.3 ± 15.6ms vs. 109.2 ± 9.6ms, P = 0.287). In the LBBP group, the interval from the left bundle branch potential to QRS onset was 28.7 ± 9.0ms. During diastole, the mean distance between the lead tip and the LV septal endocardium was 0.6 ± 0.9mm in the LBBP group and 3.0 ± 1.6mm in the LVSP group (P < 0.001). During systole, the distance was 1.5 ± 1.4mm in the LBBP group and 4.3 ± 2.6mm in the LVSP group (P < 0.001). The landing zone of the lead tip was closer to the LV septal endocardium in the patients who underwent LBBP. There is a need for real-time intraprocedural monitoring of the distance between the lead tip and the LV septal endocardium when performing LBBP.

Conduction System Pacing for Post Transcatheter Aortic Valve Replacement Patients: Comparison With Right Ventricular Pacing.

Introduction: For patients who develop atrioventricular block (AVB) following transcatheter aortic valve replacement (TAVR), right ventricular pacing (RVP) may be associated with adverse outcomes. We assessed the feasibility of conduction system pacing (CSP) in patients who developed AVB following TAVR and compared the procedural and clinical outcomes with RVP.Methods: Consecutive patients who developed AVB following TAVR were prospectively enrolled, and were implanted with RVP or CSP. Procedural and clinical outcomes were compared among different pacing modalities.Results: A total of 60 patients were enrolled, including 10 who were implanted with His bundle pacing (HBP), 20 with left bundle branch pacing (LBBP), and 30 with RVP. The HBP group had significantly lower implant success rate, higher capture threshold, and lower R-wave amplitude than the LBBP and RVP groups (p < 0.01, respectively). The RVP group had a significantly longer paced QRS duration (153.5 ± 6.8 ms, p < 0.01) than the other two groups (HBP: 121.8 ± 8.6 ms; LBBP: 120.2 ± 10.6 ms). During a mean follow-up of 15.0 ± 9.1 months, the LBBP group had significantly higher left ventricular ejection fraction (LVEF) (54.9 ± 6.7% vs. 48.9 ± 9.1%, p < 0.05) and shorter left ventricular end-diastolic diameter (LVEDD) (49.7 ± 5.6 mm vs. 55.0 ± 7.7 mm, p < 0.05) than the RVP group. While the HBP group showed trends of higher LVEF (p = 0.016) and shorter LVEDD (p = 0.017) than the RVP group. Four patients in the RVP group died—three deaths were due to progressive heart failure and one was due to non-cardiac reasons. One death in the LBBP group was due to the non-cardiac reasons.Conclusions: CSP achieved shorter paced QRS duration and better cardiac structure and function in post-TAVR patients than RVP. LBBP had a higher implant success rate and better pacing parameters than HBP.