The association between paced left ventricular activation time and cardiac reverse remodeling in heart failure patients with left bundle branch block.

INTRODUCTION: The association between paced LVAT and cardiac structure and function at baseline, as well as whether longer LVAT is associated with worse cardiac reverse remodeling in patients with heart failure (HF) and left bundle branch block (LBBB) has not been well investigated. The purpose of this study is to investigate the association between paced LVAT and baseline echocardiographic parameters and cardiac reverse remodeling at follow-up. METHODS: Patients with HF and LBBB receiving successful left bundle branch pacing (LBBP) from June 2018 to April 2023 were enrolled and grouped based on paced LVAT. NT-proBNP and echocardiographic parameters were recorded during routine follow-up. The relationships between paced LVAT and echocardiographic parameters at baseline and follow-up were analyzed. RESULTS: Eighty-three patients were enrolled (48 males, aged 65 ± 9.8, mean LVEF 32.1 ± 7.5%, mean LVEDD 63.0 ± 8.5 mm, median NT-proBNP 1057[513-3158] pg/mL). The paced QRSd was significantly decreased (177 ± 17.9 vs. 134 ± 18.5, p < .001) and median paced LVAT was 80[72-88] ms. After a median follow-up of 12[9-29] months, LVEF increased to 52.1 ± 11.2%, LVEDD decreased to 52.6 ± 8.8 mm, and NT-proBNP decreased to 215[73-532]pg/mL. Patients were grouped based on paced LVAT: LVAT < 80 ms (n = 39); 80 ≤ LVAT < 90 ms (n = 24); LVAT ≥ 90 ms (n = 20). Patients with longer LVAT had larger LVEDD and lower LVEF (LVEDDbaseline: p < .001; LVEFbaseline: p = .001). The difference in LVEF6M was statistically significant among groups (p < .001) and patients with longer LVAT had lower LVEF6M, while the difference in LVEF1Y was not seen (p = .090). There was no significant correlation between ΔLVEF6M-baseline, ΔLVEF1Y-6M and LVAT respectively (ΔLVEF6M-baseline: p = .261, r = -.126; ΔLVEF1Y-6M: p = .085, r = .218). CONCLUSION: Long paced LVAT was associated with worse echocardiographic parameters at baseline, but did not affect the cardiac reverse remodeling in patients with HF and LBBB. Those with longer LVAT required longer time to recover.

Permanent left bundle branch area pacing improves mitral regurgitation and cardiac function in patients with right bundle branch block.

BACKGROUND: Permanent left bundle branch area pacing (LBBAP) has been established as an effective means to correct left bundle branch block. Right bundle branch block (RBBB), emerge as a distinct form of cardiac conduction abnormality, can be seen in the context of LBBAP procedure. However, the correction potential of LBBAP in patients with RBBB remains largely unexplored. OBJECTIVE: The objective of this study was to evaluate the efficacy and safety of permanent LBBAP in patients with RBBB. METHODS: Ninety-two consecutive patients who underwent successful permanent LBBAP were recruited from May. 2019 to Dec. 2022 in Fuwai Central China Cardiovascular Hospital. Among them, 20 patients with RBBB were included in our analysis. These patients were followed up at 1, 3, 6 and 12 months post-LBBAP. The QRS duration (QRSd) on the V1 lead of the 12-lead elctrocardiogram was measured and compared before and after the LBBAP procedure. Additionally, mitral regurgitation, tricuspid regurgitation and cardiac function were assessed using transthoracic echocardiography, specifically focusing on left ventricular ejection fraction (LVEF) and mitral regurgitation severity. The acute pitfills and delayed complications associated with the LBBAP procedure were recorded to evaluate its safety. SPSS 23.0 was used to perform statistical analysis with Student's t test or one way ANOVA or nonparametric tests (paired Wilcoxon test). A p value less than 0.05 was defined as significant. RESULTS: The demographic breakdown of the RBBB cohort revealed a mean age of 66.35 ± 11.55 years, 60% being male. Comorbidities were prevalent, including severe atrioventricular block (AVB) in 75%, sick sinus syndrome (SSS) in 20%, heart failure in 25%, atrial fibrillation in 30%, coronary heart diseases in 45%, hypertension in 35%, and diabetes mellitus in 15%. Regarding the LBBAP procedure, the average operation time was 106.53 ± 2.72 min, with 45% of patients (9 individuals) requiring temporary cardiac pacing during the surgery. Notably, the LBBAP procedure significantly narrow the QRS duration in RBBB patients, from 132.60 ± 31.49ms to 119.55 ± 18.58 ms (P = 0.046). Additionally, at the 12-month follow-up, we observed a marked improvement in LVEF, which increased significantly from 55.15 ± 10.84% to 58.5 ± 10.55% (P = 0.018). Furthermore, mitral regurgitation severity improved, with a median reduction from 4.46 (0.9, 7.3) to 2.29 (0, 3.49) cm2 (P = 0.033). Importantly, no cases of ventricular septum perforation or pericardial effusion were reported during the LBBAP procedure or during the follow-up period. CONCLUSION: LBBAP provides an immediate reduction in QRS duration for patients suffering from RBBB, accompanied by improvements in mitral regurgitation and cardiac function as evident in the 12-month follow-up period.

Relationship Between Electrical Parameters and Cardiac Synchrony in Patients Underwent Left Bundle Branch Area Pacing.

PURPOSE: The study aims to assess cardiac synchrony under different left bundle branch area pacing (LBBAP) and evaluate the relationship between different surface or intracardiac electrical parameters and mechanical synchrony. METHODS: Eighty-two patients with successful LBBAP were recruited. The electrical synchrony, evaluated by paced QRS duration (pQRSD) and Stim-LVAT (stimulus to left ventricular activation time), and mechanical synchrony, evaluated by the standard deviation of the time-to-peak contraction velocity in 12 left ventricular segments (Tsd-12-LV), were compared between groups in patients underwent LBBAP. To investigate the relationship between different electrical parameters with mechanical synchrony under LBBAP, patients were divided into subgroups according to left ventricular activation time (LVAT, < 60, 60-70, and > 70 ms), presence of left bundle branch (LBB) potential (positive, negative), QRS axis (normal, left axis deviation [LAD]), and potential to ventricular interval (PVI, < 20 and > 20 ms). Mechanical synchrony was compared among the subgroups respectively 3 days post LBBAP procedure. RESULTS: No statistically significant differences were documented in electrical synchrony, evaluated by pQRSD, and mechanical synchrony, evaluated by Tsd-12-LV among the subgroups divided by the stim-LVAT, LBB potential, PVI duration, or paced QRS axis in the LBBAP group. CONCLUSIONS: LBB potential, PVI, or normal paced QRS axis is not the prerequisite for successful LBBAP and optimal cardiac synchrony. Adopting a Stim-LVAT value of less than 75 ms to attain ideal electrical and mechanical synchrony during the LBBAP procedure may be applicable. TRIAL REGISTRATION: http://www.chictr.org.cn/index.aspx. CLINICALTRIALS: gov identifier: ChiCTR1800021104.

Conduction System Pacing: Hope, Challenges, and the Journey Forward.

PURPOSE OF THE REVIEW: Cardiac pacing has evolved in recent years currently culminating in the specific stimulation of the cardiac conduction system (conduction system pacing, CSP). This review aims to provide a comprehensive overview of the available literature on CSP, focusing on a critical classification of studies comparing CSP with standard treatment in the two fields of pacing for bradycardia and cardiac resynchronization therapy in patients with heart failure. The article will also elaborate specific benefits and limitations associated with CSP modalities of His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). RECENT FINDINGS: Based on a growing number of observational studies for different indications of pacing therapy, both CSP modalities investigated are advantageous over standard treatment in terms of narrowing the paced QRS complex and preserving or improving left ventricular systolic function. Less consistent evidence exists with regard to the improvement of heart failure-related rehospitalization rates or mortality, and effect sizes vary between HBP and LBBAP. LBBAP is superior over HBP in terms of lead measurements and procedural duration. With regard to all reported outcomes, evidence from large scale randomized controlled clinical trials (RCT) is still scarce. CSP has the potential to sustainably improve patient care in cardiac pacing therapy if patients are appropriately selected and limitations are considered. With this review, we offer not only a summary of existing data, but also an outlook on probable future developments in the field, as well as a detailed summary of upcoming RCTs that provide insights into how the journey of CSP continues.

Left bundle branch area pacing for heart failure patients requiring cardiac resynchronization therapy: A meta-analysis.

INTRODUCTION: Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT. METHODS: We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2 > 50% indicating significant heterogeneity. RESULTS: Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2 = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2 = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2 = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2 = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2 = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2 = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2 = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2 = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2 = 0%, p = .87). CONCLUSION: This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

Feasibility and safety of zero-fluoroscopy left bundle branch pacing: An initial experience.

INTRODUCTION: Left bundle branch pacing (LBBP) has emerged in recent years as a new pacing modality, providing patients with a narrower paced QRS than conventional pacing and stable pacing parameters. At the same time, there is a growing concern about the use of fluoroscopy in pacemaker implantations, given its harmful effects on both patients and operators. However, there are no prior experiences of zero-fluoroscopy in LBBP procedure. METHODS: We conducted an observational prospective study recruiting consecutive patients that underwent zero-fluoroscopy LBBP pacemaker implantation. A 6-month follow-up visit was programmed for every patient. The main goal of our study was to assess the efficacy, feasibility, and safety of the procedure. RESULTS: From January 2021 to February 2022, we included 10 patients, 8 males. The average age was 63 ± 4 years. The procedure was successful in all patients. We observed a significant reduction in paced QRS width compared with basal QRS width (149 ± 31.9 vs. 116 ± 15.6 ms, p = .02). All device parameters remained stable at 6-month follow-up: no significant differences in mean impedance (700.5 ± 136.4 vs. 494 ± 72.7 Ohm, p = .09), capture threshold (0.67 ± 0.2 vs. 0.83 ± 0.2 V @ 0.4 ms, p = .27) or endocardial V-wave amplitude (10.6 ± 5.2 vs. 13.9 ± 6.3 mV, p = .19). No complications were reported in any case. CONCLUSION: Zero-fluoroscopy LBBP is feasible and safe, and it may be considered in cases where radiation exposure is contraindicated or especially undesirable. Future randomized clinical trials are needed for the widespread use of this new technique.

Left Bundle Branch Area Pacing Contributes to a Greater Acute Blood Pressure Reduction Compared to Right Ventricular Pacing.

Background: Several previous studies have explored the potential arterial blood pressure (BP) changes in patients undergoing right ventricular pacing (RVP), however, the relationship between left bundle branch area pacing (LBBAP) and BP variations remains unknown. This study aimed to examine the acute BP variations following LBBAP and RVP implantation in patients with bradycardia. Methods: We conducted a single-center retrospective study including all patients who underwent de-novo dual-chamber pacemaker implantation between January 2019 and June 2021. Patients were divided into two groups, LBBAP and RVP, and propensity score-matching (PSM) was used to balance confounding factors. Three time periods were defined according to the timing of the implant: baseline (within 24 hours before implantation), hyper-acute period (0-24 hours post-implantation), and acute period (24-48 hours post-implantation). BP was measured at least three times per period using an arm pressure cuff and then averaged for analysis, which allowed us to determine the acute impact of pacemaker implantation on BP. Results: From a cohort of 898 patients, 193 LBBAP receivers were matched to 193 RVP receivers. A significant decrease in systolic BP (SBP) after the implantation was observed in the study cohort, from baseline 137.3 ± 9.2 mmHg to the acute period of 127.7 ± 9.4 mmHg (p < 0.001). The LBBAP group exhibited a greater SBP reduction than the RVP group ( Δ 11.6 ± 6.2 mmHg vs. Δ 7.6 ± 5.8 mmHg, p < 0.001). In further subgroup analysis, LBBAP receivers who had high baseline SBP (p < 0.001) and those without using anti-hypertensive drugs (p = 0.045) appeared to have a higher magnitude of SBP reduction. Conclusions: Permanent pacemaker implantation may contribute to an acute decrease in systolic BP, which was more pronounced in LBBAP receivers. Future experimental and clinical investigations are necessary to explore the underlying mechanisms and the long-term hemodynamic effects of LBBAP versus RVP.

Upgrading right ventricular pacemakers to biventricular pacing or conduction system pacing: a systematic review and meta-analysis.

Guidelines recommend patients undergoing a first pacemaker implant who have even mild left ventricular (LV) impairment should receive biventricular or conduction system pacing (CSP). There is no corresponding recommendation for patients who already have a pacemaker. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies assessing device upgrades. The primary outcome was the echocardiographic change in LV ejection fraction (LVEF). Six RCTs (randomizing 161 patients) and 47 observational studies (2644 patients) assessing the efficacy of upgrade to biventricular pacing were eligible for analysis. Eight observational studies recruiting 217 patients of CSP upgrade were also eligible. Fourteen additional studies contributed data on complications (25 412 patients). Randomized controlled trials of biventricular pacing upgrade showed LVEF improvement of +8.4% from 35.5% and observational studies: +8.4% from 25.7%. Observational studies of left bundle branch area pacing upgrade showed +11.1% improvement from 39.0% and observational studies of His bundle pacing upgrade showed +12.7% improvement from 36.0%. New York Heart Association class decreased by -0.4, -0.8, -1.0, and -1.2, respectively. Randomized controlled trials of biventricular upgrade found improvement in Minnesota Heart Failure Score (-6.9 points) and peak oxygen uptake (+1.1 mL/kg/min). This was also seen in observational studies of biventricular upgrades (-19.67 points and +2.63 mL/kg/min, respectively). In studies of the biventricular upgrade, complication rates averaged 2% for pneumothorax, 1.4% for tamponade, and 3.7% for infection over 24 months of mean follow-up. Lead-related complications occurred in 3.3% of biventricular upgrades and 1.8% of CSP upgrades. Randomized controlled trials show significant physiological and symptomatic benefits of upgrading pacemakers to biventricular pacing. Observational studies show similar effects between biventricular pacing upgrade and CSP upgrade.

Conduction system pacing in everyday clinical practice: EHRA physician survey.

With the increasing interest in conduction system pacing (CSP) over the last few years and the inclusion of this treatment modality in the current guidelines, our aim was to provide a snapshot of current practice across Europe. An online questionnaire was sent to physicians participating in the European Heart Rhythm Association research network as well as to national societies and over social media. Data on previous experience with CSP, current indications, preferred tools, unmet needs, and perceptions for the future are reported and discussed.

Left Bundle Branch Pacing for Bradycardia in Non-obstructive Hypertrophic Cardiomyopathy Patients: Feasibility, Safety, and Effect.

PURPOSE: Left bundle branch pacing (LBBP) is as an innovative physiological pacing approach. The research on LBBP in non-obstructive hypertrophic cardiomyopathy (NOHCM) patients is scarce. This study aimed to assess the feasibility, safety, and effect of LBBP in bradycardia NOHCM patients with permanent pacemaker (PPM) implantation indication. METHODS: Thirteen consecutive patients with NOHCM who received LBBP were retrospectively enrolled as a hypertrophic cardiomyopathy (HCM) group. Following 1:3 matching, 39 patients without HCM were randomly matched as a control group. Echocardiographic index and pacing parameters were collected. RESULTS: The successful LBBP was achieved in 96.2% of all cases (50/52), and the success rate of the HCM group was 92.3% (12/13). In the HCM group, the paced QRS duration (from the pacing stimulus to QRS end) was 145.6±20.8 ms. The stimulus to left ventricular activation time (s-LVAT) was 87.4±15.2 ms. In the control group, the paced QRS duration was 139.4±17.2 ms, and the s-LVAT was 79.9±14.1 ms. During the implantation, R-wave sensing and the pacing threshold of the HCM group were significantly higher than the control group (20.2±10.5 vs 12.5±5.9 mV, P < 0.05; 0.8±0.3 vs 0.6±0.2V/0.4 ms, P < 0.05). In addition, the fluoroscopic duration and procedural duration were longer in the HCM group (14.8±8.3 vs 10.3±6.6min, P = 0.07; 131.8±50.5 vs 101.4±41.6 min, P < 0.05). The lead insertion depth was 15±2 mm in the HCM group, and no procedure-related complications occurred. During the 12-month follow-up, pacing parameters remained stable and were of no significance in the two groups. The cardiac function did not deteriorate, and the left ventricular outflow tract gradient (LVOTG) did not increase in the follow-up. CONCLUSION: LBBP might be feasible and safe for NOHCM patients with conventional bradycardia pacing indication, and there is no deterioration in cardiac function and LVOTG of patients with NOHCM.

Left bundle branch pacing in alternating bundle branch block.

We present a case of symptomatic intermittent AV block showing during monitorization alternating bundle branch block. Presuming a high need of pacing, conduction system pacing was considered a more physiological alternative in this patient. Left bundle branch pacing restored a stable atrioventricular synchrony with a paced QRS complex similar to the native one and might be a good alternative in these cases.

Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing.

BACKGROUND: The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited. METHODS AND RESULTS: We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12­lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI). RESULTS: QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning. CONCLUSIONS: QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Left bundle branch pacing as an alternative to biventricular pacing for cardiac resynchronisation therapy.

BACKGROUND: Left bundle branch pacing (LBBP) is a novel physiological pacing technique which may serve as an alternative to biventricular pacing (BVP) for the delivery of cardiac resynchronisation therapy (CRT). This study assessed the feasibility and outcomes of LBBP in comparison to BVP. METHODS: LBBP was attempted in 40 consecutive patients as the first-line method for delivering CRT. To evaluate LBBP versus BVP, 40 patients with identical inclusion criteria who received BVP were compared with the LBBP group. Acute success rate, complications, functional and echocardiographic outcomes as well as hospitalisation for heart failure and all-cause mortality 6 months after implantation were evaluated. RESULTS: LBBP was successfully performed in 31 (78%) patients and resulted in significant QRS narrowing (from 166 ± 16 to 123 ± 18 ms, p < 0.001), improvement in left ventricular ejection fraction (LVEF; from 28 ± 8 to 43 ± 12%, p < 0.001) and New York Heart Association functional class (from 2.8 ± 0.5 to 1.6 ± 0.6, p < 0.001) at 6 months. No LBBP-related complications occurred. Compared to BVP, LBBP resulted in a greater reduction in QRS duration (44 ± 17 vs 15 ± 26 ms, p < 0.001) with comparable absolute improvement in LVEF (15.2 ± 11.7 vs 9.6 ± 12.1%, p = 0.088). Hospitalisation for heart failure and all-cause mortality were similar in the two groups. CONCLUSIONS: LBBP is feasible and was safe in 78% of patients with favourable electrical resynchronisation and functional improvement and may serve as an alternative to BVP.

Computed tomography imaging-identified location and electrocardiographic characteristics of left bundle branch area pacing in bradycardia patients.

INTRODUCTION: Left bundle branch area pacing (LBBAP) is a novel physiological pacing modality. The relationship between the pacing lead tip location and paced electrocardiographic (ECG) characteristics remains unclear. The objectives are to determine the lead tip location within the interventricular septum (IVS) and assess the location-based ECG QRS duration (QRSd) and left ventricular activation time (LVAT). METHODS: This multicenter study enrolled 50 consecutive bradycardia patients who met pacemaker therapy guidelines and received LBBAP implantation via the trans-ventricular septal approach. After at least 3 months postimplant, 12-lead ECGs and pacing parameters were obtained. Cardiac computed tomography (CT) imaging was performed to assess the LBBAP lead tip distance from the LV blood pool. RESULTS: Among the 50 patients, analyzable CT images were obtained in 42. In 23 of the 42 patients, the lead tips were within 2 mm to the LV blood pool (the LV subendocardial (LVSE) group), 13 between 2 and 4 mm (the Near-LVSE group), and the remaining 6 beyond 4 mm (the Mid-LV septal (Mid-LVS) group). No significant differences in paced QRSd were found among the three groups (LVSE, 107 ± 15 ms; Near-LVSE, 106 ± 13 ms; Mid-LVS, 104 ± 15 ms; p = .87). LVAT in the LVSE (64 ± 7 ms) was significantly shorter than in the Mid-LVS (72 ± 8 ms; p < .05), but not significantly different from that in the Near-LVSE (69 ± 8 ms; p > .05). CONCLUSION: In routine LBBAP practice, paced narrow QRSd and fast LVAT, indicative of physiological pacing, were consistently achieved for lead tip location in the LV subendocardial or near LV subendocardial region.

Preliminary study on left bundle branch area pacing in children: Clinical observation of 12 cases.

INTRODUCTION: Left bundle branch area pacing (LBBAP) maintains electrical and mechanical synchronization of the ventricles. It is a relatively physiological pacing mode, with low and stable pacing threshold and wider indications. LBBAP in children has been rarely reported. METHODS: This study observed 12 children attempted LBBAP from January 2019 to January 2021 in the department of pediatric cardiology of Anzhen Hospital prospectively. Clinical data, pacing parameters, electrocardiograms, intracardiac electrograms, echocardiographic measurements and complications were recorded at implant and during follow-up. RESULTS: The 12 patients aged between 3 and 14 years old and weighted from 13 to 48 kg. Eleven patients were diagnosed with third-degree atrioventricular block and 1 patient (case 4) suffered from cardiac dysfunction due to right ventricular apical pacing (RVAP). Left bundle branch area pacing was successfully achieved in all patients with narrow QRS complexes and V1 lead showed changes like right bundle branch block in the pacing electrocardiogram. Left ventricular ejection fraction in case 4 recovered on the 3rd day after LBBAP. The median of left ventricular end diastolic diameter Z score of the 12 patients decreased from 1.75 to 1.05 3 months after implantation (p < 0.05). The median of paced QRS duration was 103 ms. The median of pacing threshold, R-wave amplitude and impedance were 0.85 V, 15 mV and 717 Ω respectively and remained stable during follow-up. No complications such as loss of capture, lead dislodgement or septal perforation occurred. CONCLUSIONS: Left bundle branch area pacing can be performed safely in children with narrow QRS duration and stable pacing parameters. Cardiac dysfunction caused by long-term RVAP can be corrected by LBBAP quickly.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: LBBP is a pacing technique that seems to associate with a positive and protective impact on RV performance.

Comparisons of electrophysiological characteristics, pacing parameters and mid- to long-term effects in right ventricular septal pacing, right ventricular apical pacing and left bundle branch area pacing.

BACKGROUND: As a near-physiological pacing innovation, left bundle branch area pacing (LBBAP) has drawn much attention recently. This study was aimed to investigate the electrophysiological characteristics, unipolar/bipolar pacing parameters and mid- to long-term effects and safety of three different pacing methods and identify possible predictors of adverse left ventricular remodeling. METHODS: Ninety-two patients were divided into the LBBAP group, right ventricular septal pacing (RVSP) group and right ventricular apical pacing (RVAP) group. Baseline information, electrophysiological, pacing and echocardiographic parameters were collected. RESULTS: The three pacing methods were performed with a similar high success rate. The paced QRSd was significantly different among the LBBAP, RVSP and RVAP groups (105.93 ± 15.85 ms vs. 143.63 ± 14.71 ms vs. 155.39 ± 14.17 ms, p < 0.01). The stimulus to left ventricular activation time (Sti-LVAT) was the shortest in the LBBAP group, followed by the RVSP and RVAP groups (72.80 ± 12.07 ms vs. 86.29 ± 8.71 ms vs. 94.14 ± 10.14 ms, p < 0.001). LBBAP had a significantly lower tip impedance during the procedure and 3-month follow up as compared to RVSP and RVAP (p < 0.001). Higher bipolar captured thresholds were observed in LBBAP during the procedure (p < 0.001). Compared to the baseline values, there was a greater reduction in left ventricular end-diastolic dimension (LVEDD) in the LBBAP group (p = 0.046) and a significant enlargement in LVEDD in the RVAP group (p = 0.008). Multiple regression analysis revealed that the Sti-LVAT was a significant predictor of LVEDD at 12 months post-procedure. At the 24-h post-procedure, significant elevations were observed in the cTnI levels in LBBAP (p < 0.001) and RVSP (p < 0.05). More transient RBB injury was observed in LBBAP. But no significant difference was found in cardiac composite endpoints among three groups (p > 0.05). CONCLUSIONS: LBBAP demonstrated a stable captured threshold, a low tip impedance and a high R-wave amplitude during the 12-month follow-up. Left ventricular remodeling was improved at 12 months post-procedure through LBBAP. The Sti-LVAT was a significant predictor of left ventricular remodeling. LBBAP demonstrated its feasibility, effectiveness, safety and some beneficial electrophysiological characteristics during this mid- to long-term follow-up, which should be confirmed by further studies.

Septal flash correction with His-Purkinje pacing predicts echocardiographic response in resynchronization therapy.

BACKGROUND: His-Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to Cardiac Resynchronization Therapy (CRT); however, predictors of echocardiographic response have not been described in this population. Septal flash (SF), a fast contraction and relaxation of the septum, is a marker of intraventricular dyssynchrony. METHODS: The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. This retrospective analysis of prospectively collected data included 30 patients. Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6-month follow-up. Echocardiographic response was defined as increase in five points in LVEF. RESULTS: HPCSP shortened QRS duration by 48 ± 21 ms and SF was significantly decreased (baseline 3.6 ± 2.2 mm vs. HPCSP 1.5 ± 1.5 mm p < .0001). At 6-month follow-up, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r = .61, p = .004). A correction of ≥1.5 mm (baseline SF - paced SF) had a sensitivity of 81% and 80% specificity to predict echocardiographic response (area under the curve 0.856, p = .019). CONCLUSION: HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6-month follow-up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6-month follow-up.

Left ventricular septal pacing versus left bundle branch pacing in the treatment of atrioventricular block.

BACKGROUND: This study aimed to evaluate the feasibility and clinical response of LVSP as an alternative to LBBP. METHODS: This was a retrospective study of pacemaker implantation, and 46 consecutive patients with pacemaker implantation were enrolled in the study. The patients were divided into the LBBP and LVSP groups. Electrocardiogram characteristics, pacing parameters, cardiac function, and safety events were assessed during implantation and 12-month follow-up. RESULTS: The procedure time was significantly increased in the LBBP group compared with the LVSP group (53.52 ± 14.39 min vs. 38.13 ± 11.52 min, respectively, p = .000). The pacing QRS duration (PQRSD) decreased by 14.09 ± 41.80 ms in the LBBP group and increased by 9.70 ± 29.60 ms in the LVSP group (p = .031). Furthermore, the left ventricle activation time (LVAT) was shorter in the LBBP group than in the LVSP group (48.70 ± 13.67 ms vs. 58.70 ± 13.67 ms, p =  .032). During the 12-month follow-up, pacing thresholds remained low and stable, and there was no significant decrease in cardiac function. No adverse event was observed during the follow-up period. CONCLUSIONS: Both LBBP and LVSP are safe and feasible methods. LVSP is a good option when multichannel electrophysiological instruments are not available and when the time available for the procedure is limited.

Permanent Left Bundle Branch Area Pacing for High-Degree Atrioventricular Block in a 6-Year-Old Child with 2-Year Follow-Up.

The feasibility and safety of left bundle branch area pacing (LBBAP) used in pediatric patients with atrioventricular block (AVB) have not been well demonstrated. Currently, only several case reports for pediatric patients have been published since the advent of LBBAP, with 3 months to 1 year follow-up. Here, we present a case of LBBAP in a 6-year-old child with a high-degree AVB secondary to the transcatheter device closure of congenital ventricular septal defect. No procedure-related complications were observed, and the electrical parameters were stable at 2-year follow-up. Additionally, we performed a systematic literature review on pediatric patients with LBBAP. Fifteen cases were retrieved after systematically searching PubMed and Embase databases. No complications have been reported among these published cases. In conclusion, consistent with previous cases, our case with 2-year follow-up has demonstrated that LBBAP may be an alternative pacing modality from a very early age. However, given the limited evidence, the long-term outcomes of LBBAP in pediatric patients should be further investigated.