Low Pacing Thresholds Research Articles

Safety and performance of conduction system pacing: Real-world experience from a product surveillance registry

BackgroundConduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), has been used as an alternative for pacemaker indicated patients requiring ventricular pacing. ObjectiveThe purpose of this study was to characterize the safety and performance of HBP and LBBAP among patients enrolled in the Medtronic product surveillance registry (PSR). MethodsThis observational analysis included patients who underwent pacemaker implantations for HBP or LBBAP with a Medtronic Model 3830 lead between January 2019 and December 2023 in the Medtronic PSR. The primary outcomes were lead-related complications and pacing capture threshold. Baseline characteristics, R-wave amplitude, impedance, and all-cause mortality were summarized. ResultsA total of 2342 patients were included across 77 centers (mean age 74 years; 38.9% female). Of the patients implanted with a 3830 lead for CSP, 64.1% (n = 1502) had LBBAP placement and 35.9% (n = 840) had HBP placement. The most commonly reported indications for CSP were sinus node dysfunction (67.0%) and atrioventricular block (57.2%). LBBAP had lower pacing thresholds, higher R-wave sensing, and higher impedance (all P <.001) through 30 months. At 36 months postimplant, the lead complication rate for LBBAP and HBP was 2.5% and 6.3%, ,respectively with no difference in all-cause mortality. ConclusionIn a multicenter cohort of LBBAP and HBP patients treated with the catheter-delivered 3830 lead, lead-related complication rates were low and electrical parameters were stable through 30 months.

Complementary use of conduction system pacing techniques for the “pace and ablate” strategy in permanent atrial fibrillation - a case report

Abstract Introduction The feasibility of the conduction system pacing combined with atrioventricular node ablation was demonstrated in patients with atrial fibrillation in whom rate control can’t be achieved with medication and heart failure. Clinical case We present a case of an 82-year-old man with a personal history of permanent atrial fibrillation, admitted with symptoms of heart failure. The resting electrocardiogram showed a very fast ventricular response, and the echocardiography showed a depressed left ventricular function, raising the suspicion of a tachycardia-mediated cardiomyopathy. Since the patient was on maximum doses of atrioventricular nodal-blocking drugs, we opted for a physiological pacing and atrioventricular node ablation strategy. First, the His bundle capture was achieved at low pacing thresholds, and ablation of the atrioventricular node was attempted. Unfortunately, after several failed attempts, an acute increase in the His bundle capture threshold was noted, suggesting inadvertent tissue ablation beneath the pacing lead. In this scenario, we removed the lead from the His bundle area and achieved optimal left bundle branch area pacing. With the lead in this position, atrioventricular node ablation was performed during the first attempt. At the six-month follow-up, there was no recovery of atrioventricular node conduction. Device interrogation revealed stable pacing and sensing parameters, and there was a significant improvement in clinical status and left ventricular function. Conclusions Mastering both His bundle pacing and left bundle branch area pacing offers the potential to overcome intraprocedural challenges, giving alternative strategies to achieve physiological pacing. These approaches can be used interchangeably based on the evolving dynamics of the procedure and the patient’s specific needs.

Feasibility and safety of physiologic pacing post-TAVR

Abstract Introduction His-Purkinje conduction system pacing (HPCSP) is an increasingly used technique due to its benefits. The transcatheter aortic valve replacement (TAVR) has in turn been growing and surpasses the number of procedures than surgical aortic valve replacement, however, the main disadvantage with respect to the surgical technique is a greater risk of atrioventricular block and the need for permanent pacing. Purpose Assess the feasibility of HPCSP in patients after TAVR, the success rates and the pacing thresholds. Methods We present a series of consecutive patients (undergoing TAVI in a single center with need for subsequent ventricular stimulation (n=58), from March 2019 to July 2023, performing HPCSP as the first stimulation option. Results We achieved HPCSP in 49 of 58 patients (84.5%). Patients had a mean age of 81.5 years, 60.3% men, mean LVEF 53.82 ± 12.4%. His bundle pacing (HBP) was successful as first option in 41.4% of cases, and left bundle branch area (LBBAP) in 43,1 % of cases (73.5% of the remaining 58.6%) , while the other 9 patients (15.5%) were pace conventionally at right ventricle, septal or wireless. HBP thresholds and R-wave amplitudes at implantation were 0.99 ± 0.72 at 0.5 ms, 4.59 ± 3.67 mV), remaining stable at follow-up at 1 month (1.16 ± 0.92 at 0.5 ms, 4.17 ± 3.97 mV),. Average QRS width was40.8 ± 21.3 ms pre and 122.43 ± 15.2 ms post). LBBAP pacing thresholds and R-wave amplitudes were(0.89 ± 0.45 at 0.5 ms, 6.145 ± 5.3 mV)at implant, and were stable at follow-up at 1 month (0.75 ± 0.3 at 0.5 ms, 8.41 ± 5.8 mV), with no improvements on QRS (129.75 ± 21.01 ms pre, 134.13 ± 17.34 ms post). During a mean follow-up of 23 months. There has been no acute elevation of thresholds or need for reintervention. Only 6 patients have died (10.3%), 2 of them (33%) from cardiovascular causes. Conclusions HPCSP is feasible as a routine techniquein patients after TAVR who need a pacemaker implantation, with low pacing thresholds, which remained stable on the follow-up.

Feasibility and safety of permanent left bundle branch area pacing in pediatric patients

Abstract Introduction Left bundle branch area pacing (LBBAP) is a promising pacing strategy with a low and stable pacing threshold. It maintains electrical and mechanical synchronization of the ventricles. Conduction system pacing (CSP) has evolved rapidly to become the pacing method of choice for many adult and pediatric patients. Recent studies have begun to demonstrate the feasibility and efficacy of CSP in pediatric patients. Nowadays, research articles about LBBAP in children are comparatively rare, therefore, research in this area is preferred. Limited data on LBBAP in pediatric patients (≤ 18 years old) are available. Purpose This study aims to describe the feasibility and safety of LBBAP in pediatric patients. Methods This study includes 4 patients: 1 male, and 3 females, respectively. The average age of the patients was 15.5±1.9 years and the weight was 51,5±17,6 kg. All patients were diagnosed with 3rd-degree atrioventricular (AV) block, in one case the total AV block occurred after previous radiofrequency ablation of the parahisian and right lateral accessory pathway. One patient had previously been implanted with an epicardial pacemaker and presented to our clinic with ventricular lead dysfunction. Pacing parameters were assessed during implantation, the next day after the procedure, and 1, 3 months follow-up. Echocardiography was performed to evaluate LV function and assess the approximate lead location and impact on tricuspid valve function. Results LBBAP was successfully achieved in all patients resulting in narrow QRS complexes (102±12.7ms) and right bundle branch block QRS morphology. To confirm left bundle branch area capture, peak left ventricular activation time (pLVAT) (84.5±4.1ms), V6-V1 (43.5±2.5ms) inter-peak interval, presence of left bundle potential, transition from non-selective to selective capture were recorded at during the implantation. The mean paced QRS duration was (108±13 ms). Pacing threshold and impedance remain stable (0.75±0.25V, and 615±50 Ohm, respectively). There was no major complication during the implanting process and follow-up. Conclusions LBBAP can be performed safely in children with narrow QRS complexes and can achieve stable pacing parameters.

Aveir VR real-world performance and chronic pacing threshold prediction using mapping and fixation electrical data.

Aveir VR performance and predictors for its pacing threshold (PCT) in a real-world cohort were investigated. Electrical measurements at various stages of an Aveir VR implant were prospectively collected. Predictors for 3-month PCT were studied. A retrospective cohort of consecutive 139 Micra implants was used to compare the PCT evolution. High PCT was defined as ≥1.5 V, using a pulse width of 0.4 ms for Aveir and 0.24 ms for Micra. Excellent PCT was defined as ≤0.5 V at the respective pulse width. Among the 123 consecutive Aveir VR implant attempts, 122 (99.2%) were successful. The majority were of advanced age (mean 79.7) and small body size (mean BSA 1.60). Two patients (1.6%) experienced complications, including one pericardial effusion after device reposition and one intraoperative device dislodgement. Eighty-eight patients reached a 3-month follow-up. Aveir 3-month PCT was correlated with impedance at mapping (P = 0.015), tether mode (P < 0.001), end-of-procedure (P < 0.001), and mapping PCT (P = 0.035), but not with PCTs after fixation (P > 0.05). Tether mode impedance >470 ohms had 88% sensitivity and 71% specificity in predicting excellent 3-month PCT. Although it is more common for Aveir to have high PCT at end of procedure (11.5% for Aveir and 2.2% for Micra, P = 0.004), the rate at 3 months was similar (2.3% for Aveir and 3.1% for Micra, P = 1.000). Aveir VR demonstrated satisfactory performance in this high-risk cohort. Pacing thresholds tend to improve to a greater extent than Micra after implantation. The PCT after fixation, even after a waiting period, has limited predictive value for the chronic threshold. Low-mapping PCT and high intraoperative impedance predict chronic low PCT.

Left bundle branch area pacing in patients with CRT indication: short-term results &amp; 1-year follow-up

Abstract Background Cardiac resynchronization therapy (CRT) using bi-ventricular pacing is class I recommendation for symptomatic patients with heart failure (LVEF ≤35%), QRS duration ≥150 msec and LBBB QRS morphology. Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT. The aim of this study was to assess the feasibility and outcomes of LBBAP in patients eligible for CRT. Methods Patients with CRT indications were subjected to LBBAP. Peri-procedural outcomes &amp; QRS duration were recorded. Changes in New York Heart Association (NYHA) class, need for HF hospitalization, echocardiographic data, lead-device parameters were evaluated at follow-up. HF status was assessed by clinical (no HF hospitalization and improvement in NYHA class) and echocardiographic response (≥5% improvement in LVEF). Results LBBAP was attempted in 16 patients (mean age 59.3 ±7.04 years, 37.5% women, ischemic cardiomyopathy in 33.3%). All patients had baseline LBBB. Pacing threshold and R-wave amplitudes were 0.8 ± 0.3 V at 0.5 ms and 12.1 ± 3.5 mV at implantation and remained stable during mean follow-up of 11.25 ± 3.7 (Range 6-18) months. LBBAP resulted in significant QRS narrowing from 147.5 ± 9.7 to 116 ± 10.2 ms (p &amp;lt; 0.01). LVEF improved from 28.2 ± 2.8% to 38.9 ± 5.1% (p &amp;lt; 0.01). Clinical and echocardiographic improvement was observed in 77% and 74% of patients, respectively. Conclusions LBBAP is feasible, safe and effective. It provides an alternative option for CRT. LBBAP provides low and stable pacing thresholds and is associated with improved clinical and echocardiographic outcomes.

Abstract 14047: Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Patients With Left Ventricular Systolic Failure: A Systematic Review and Meta-Analysis

Introduction: There is limited data comparing the effectiveness of Left Bundle Branch Area Pacing (LBBAP) and traditional Biventricular Pacing (BiVP) in patients with left ventricular systolic failure. The aim of this study was to assess the electromechanical and clinical outcomes of both cardiac resynchronization (CRT) techniques. Hypothesis: LBBAP offers comparable or superior clinical outcomes compared to BiVP in patients with systolic left ventricular failure Methods: We conducted a systematic review of PubMed (MEDLINE), Embase, Google Scholar, Scopus, and Cochrane Central Register of Control Trials (CENTRAL) for studies comparing LBBAP with BiVP from inception till May 22, 2023. To evaluate categorical and continuous outcomes, risk ratios (RRs) and standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs) were calculated using RevMan version 5.4 software. Results: We selected 12 studies involving 3,004 patients (LBBP=1,242; BiVP=1,762) for our meta-analysis. The pooled results demonstrated significant improvements with LBBAP in left ventricular ejection fraction (LVEF) (SMD=0.40, 95%CI[0.25, 0.54], P&lt;0.00001), NYHA functional class (SMD=-0.44, 95%CI[-0.65, -0.23], P&lt;0.0001), reduction in QRS duration (SMD=-0.90, 95%CI[-1.14, -0.66], P&lt;0.00001), fewer heart failure hospitalizations (RR=0.72, 95%CI [0.62, 0.85], P&lt;0.0001), and improved survival (RR=0.73, 95%CI [0.58, 0.92], P=0.007). Additionally, LBBAP was associated with a lower pacing threshold at implantation (SMD=-1.03, 95%CI[-1.32, -0.74], P&lt;0.00001) as compared to BiVP. Conclusions: LBBAP was associated with significant improvements in both electromechanical and clinical outcomes, including LVEF, reduction in QRS duration, NYHA class, heart failure hospitalizations, and all-cause mortality in patients with systolic left ventricular failure.

Left bundle branch area pacing vs biventricular pacing for cardiac resynchronization: A systematic review and meta-analysis

Left bundle branch area pacing (LBBAP) may offer greater physiological benefits than traditional biventricular pacing (BiVP). However, there are limited data comparing the efficacy of LBBAP vs BiVP in patients with systolic heart failure (HF). The purpose of this meta-analysis was to compare the feasibility and electromechanical and clinical outcomes of both LBBAP and BiVP. We conducted a systematic review of studies retrieved from various databases including PubMed, Embase, Google Scholar, Scopus, and Cochrane Central Register of Control Trials (CENTRAL) published up to May 22, 2023. The risk ratio (RR) and standardized mean difference (SMD) with corresponding 95% confidence intervals (CIs) were calculated for dichotomous and continuous outcomes, respectively. We included 12 studies with a total of 3004 patients (LBBAP = 1242, BiVP = 1762). Pooled results showed that LBBAP resulted in a significant increase in left ventricular ejection fraction (SMD 0.40, 95% CI 0.25, 0.54, P < .00001), echocardiographic response (RR 1.19, 95% CI 1.10 to 1.29, P < .0001), improvement in New York Heart Association functional class (SMD -0.44, 95% CI -0.65 to -0.23, P < .0001), QRS duration reduction (SMD -0.90, 95% CI -1.14 to -0.66, P < .00001), left ventricular end-diastolic diameter reduction (SMD -0.31, 95% CI -0.57 to -0.05, P = .02), fewer HF hospitalizations (RR 0.72, 95% CI 0.62, 0.85, P < .0001), and improved survival (RR 0.73, 95% CI 0.58, 0.92, P = .007). In addition, LBBAP was associated with shorter fluoroscopy time (SMD -0.94, 95% CI -1.42 to -0.47, P < .0001) and lower pacing threshold at implantation (SMD -1.03, 95% CI -1.32 to -0.74, P < .00001) and at 6 months (SMD -1.44, 95% CI -2.11 to -0.77, P < .0001) as compared with BiVP. Compared with BiVP, LBBAP was associated with better electromechanical and clinical outcomes, including left ventricular ejection fraction, QRS duration, echocardiographic response, New York Heart Association functional class, HF hospitalization, and all-cause mortality in patients with systolic HF.

Effectiveness of conduction system pacing for cardiac resynchronization therapy: A systematic review and network meta-analysis.

Cardiac resynchronization therapy (CRT) with biventricular pacing (BiV-CRT) is ineffective in approximately one-third of patients. CRT with Conduction system pacing (CSP-CRT) may achieve greater synchronization. We aimed to assess the effectiveness of CRT with His pacing (His-CRT) or left bundle branch pacing (LBB-CRT) in lieu of biventricular CRT. The PubMed, Embase, Web of Science, Scopus, and the Cochrane Library were systematically searched until August 19, 2023, for original studies including patients with reduced left ventricular ejection fraction (LVEF) who received His- or LBB-CRT, that reported either CSP-CRT success, LVEF, QRS duration (QRSd), or New York Heart Association (NYHA) classification. Effect measures were compared with frequentist network meta-analysis. Thirty-seven publications, including 20 comparative studies, were included. Success rates were 73.5% (95% CI: 61.2-83.0) for His-CRT and 91.5% (95% CI: 88.0-94.1) for LBB-CRT. Compared to BiV-CRT, greater improvements were observed for LVEF (mean difference [MD] for His-CRT +3.4%; 95% CI [1.0; 5.7], and LBB-CRT: +4.4%; [2.5; 6.2]), LV end-systolic volume (His-CRT:17.2mL [29.7; 4.8]; LBB-CRT:15.3mL [28.3; 2.2]), QRSd (His-CRT: -17.1ms [-25.0; -9.2]; LBB-CRT: -17.4ms [-23.2; -11.6]), and NYHA (Standardized MD [SMD]: His-CRT:0.4 [0.8; 0.1]; LBB-CRT:0.4 [-0.7; -0.2]). Pacing thresholds at baseline and follow-up were significantly lower with LBB-CRT versus both His-CRT and BiV-CRT. CSP-CRT was associated with reduced mortality (R = 0.75 [0.61-0.91]) and hospitalizations risk (RR = 0.63 [0.42-0.96]). This study found that CSP-CRT is associated with greater improvements in QRSd, echocardiographic, and clinical response. LBB-CRT was associated with lower pacing thresholds. Future randomized trials are needed to determine CSP-CRT efficacy.

PO-01-024 FEASIBILITY, SAFETY AND LONG-TERM OUTCOMES OF LEFT BUNDLE BRANCH PACING – THE AUSTRALIAN EXPERIENCE

Left bundle branch pacing (LBBP) has shown to be safe and effective, observing low and stable pacing thresholds. Considering it being a relatively new technology, long-term outcomes of this pacing modality is still unclear. We aimed to prospectively assess the efficacy, long-term effects, and safety of LBBP in consecutive patients requiring right ventricular pacing. Heart failure patients and patients requiring cardiac resynchronisation therapy were excluded from this study. In this cohort study, consecutive patients requiring pacing therapy were enrolled. Permanent LBBP leads were implanted if the left bundle branch (LBB) capture threshold was <2.5V/0.5 ms. Pacing parameters, ECG parameters, complications and echocardiographic measurements were assessed during follow-up. In 156 enrolled patients (67±7 years of age), LBB capture was acutely achieved in 147 (94%) patients, and 134 (91%) patients received permanent LBBP. 13 (9%) patients did not receive permanent LBBP, due to no LBB capture (n=6), high LBB capture thresholds (n=5) and fixation failure (n=2). The median follow-up period of permanent LBBP was 55±6 months. LBB capture threshold remained stable with acute threshold of 1.82±0.91 V/0.5 ms to 2.09±0.12 V/0.5 ms at 5-year follow-up (p>0.05). Mean percentage right ventricular pacing was 33±9%. Mean paced QRS duration at implant was 93±6 ms and at final follow-up was 101±3 ms (p>0.05). Mean left ventricular ejection fraction at baseline was 51.4±2.1%, which remained stable at 54.7±1.8% at final follow-up (p>0.05). At baseline, left atrial indexed volume was 31±2mL/m2 and at final follow-up remained stable at 33±1.5mL/m2 (p>0.05). No patient had worsening of right ventricular function, mitral or tricuspid regurgitation. This large observational study suggests that left bundle branch pacing is feasible, safe and effective with high success rates and low complication rates during long-term follow-up. Therefore, left bundle branch pacing appears to be a reliable method for physiological pacing in patients with bradycardia indication.

Cardiac resynchronization therapy in heart failure patients by using left bundle branch pacing.

BackgroundLeft bundle branch pacing (LBBP) is emerging as an effective alternative to achieve cardiac resynchronization therapy (CRT) and improve heart function. The purpose of our study was to investigate the feasibility and efficacy of LBBP in heart failure patients with left ventricular ejection fraction (LVEF) <50% and left bundle branch block (LBBB).MethodsAll patients with complete LBBB and LVEF <50% were retrospectively included in the study from April 2018 to April 2021 and underwent CRT via LBBP implantation. ECG, pacing parameters, the New York Heart Association (NYHA) functional class, echocardiographic measurements, and complications were recorded and analyzed at implant and during follow-up of 1, 6, and 12 months.ResultsLeft bundle branch pacing was successful in all 34 patients (mean age 65.6 ± 11.2 years, 67.6% men). A significant decrease in QRS duration (QRSd) was observed after the LBBP operation for 1 month (153.2 ± 1.7 vs. 111.9 ± 2.6 ms, p < 0.01). LBB capture threshold and R-wave amplitude remained stable at 12-month follow-up when compared with implantation values (0.62 ± 0.13 V @ 0.4 ms vs. 0.73 ± 0.21 V @ 0.4 ms, 12.02 ± 5.68 mV vs. 8.58 ± 4.09 mV, respectively). LVEF increased significantly (35.28 ± 1.70% vs. 51.09 ± 1.71%, p < 0.01) accompanied with reduced left ventricular end-diastolic dimension (LVEDd; 65.3 ± 1.99 vs. 53.58 ± 2.07 mm, p < 0.01) and left atrial dimension (LAD; 49.03 ± 1.32 vs. 40.67 ± 1.58 mm, p < 0.01). Normalized LVEF (LVEF ≥ 50%) was found in 70.5% of patients at 12 months. The NYHA classification, brain natriuretic peptide (BNP), and 6-minute walk test (6MWT) were significantly improved at follow-up of 12 months (all p < 0.01 vs. baseline). No deaths or heart failure hospitalizations were observed during the follow-up period.ConclusionThe current work suggested that LBBP was feasible with a high success implantation rate and effective to correct LBBB and improved left ventricular structure and function with a low and stable pacing threshold.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: A multicenter study.

Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This registry study explores the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design in a multicenter patient population. This study prospectively enrolled consecutive patients who underwent LBBAP for bradycardia pacing or heart failure indications at eight Belgian hospitals. LBBAP was attempted using SDL (Solia S60; Biotronik) delivered through dedicated delivery sheath (Selectra3D). Implant success, complications, procedural, and pacing characteristics were recorded at implant and follow-up. The study enrolled 353 patients (mean age 76 ± 39 years, 43% female). The mean number of implants per center was 25 (range: 5-162). Overall, LBBAP with SDL was successful in 334/353 (94%), varying from 93% to 100% among centers. Pacing response was labeled as left bundle branch pacing in 73%, whereas 27% were labeled as myocardial capture. Mean paced QRS duration and stimulus to left ventricular activation time measured 126 ± 21 ms and 74 ± 17. SDL-LBBAP resulted in low pacing thresholds (0.6 ± 0.4 V at 0.4 ms), which remained stable at 12 months follow-up (0.7 ± 0.3, p = .291). Lead revisions for SDL-LBBAP occurred in 5 (1.4%) patients occurred during a mean follow up of 9 ± 5 months. Five (1.4%) septal coronary artery fistulas and 8 (2%) septal perforations occurred, none of them causing persistent ventricular septal defects. The use of SDL to achieve LBBAP is safe and feasible, characterized by high implant success in low and high volume centers, low complication rates, and stable low pacing thresholds.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: a multicenter study

Abstract Funding Acknowledgements Type of funding sources: None. Background Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This study is the first to explore in a multicenter population the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design. Methods This study prospectively enrolled all consecutive patients who underwent LBBAP for anti-bradycardia pacing or heart failure indications at 8 Belgian hospitals. LBBAP was attempted either using SDL or LLL delivered through dedicated delivery sheaths. Implant success, complications, procedural and pacing characteristics were recorded at implant and follow-up. Results The study enrolled 412 patients (mean age 74 ± 38 years, 44% female). LBBAP with SDL and LLL was successful in 334/353 (94%) and 52/59 (88%) respectively (p=0.058). Implant success for LBBAP using SDL varied from 93 to 100% among centers. Mean paced QRS duration and stimulus to left ventricular activation time were comparable for SDL and LLL (126 ± 21ms versus 125 ± 22ms, p=0.861 and 74 ± 17 and 75 ± 21ms, p=0.756). SDL LBBAP resulted in low pacing thresholds (0.6 ± 0.4V at 0.4ms), which remained stable at 1, 6 and 12 months of follow-up. Lead revisions for SDL LBBAP occurred in 5(1.4%) patients: 2 dislodgements at day 1, 1 late septal perforation at week 3, 1 Twiddler’s syndrome at 5 months, 1 lead fracture at 6 months. Conclusion This multicenter study confirms the safety and feasibility of LBBAP using SDL, which is characterized by high implant success, low complication rate and low and stable pacing thresholds.

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

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. 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. 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. 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.

Transventricular Left Bundle Branch Pacing

Background. Implementation of conduction system permanent pacing methods in patients with cardiac bradyarrhythmias allows to maintain the physiological sequence of excitation and contraction of the ventricles and to avoid the development of heart failure due to electrical and mechanical dyssynchrony in patients with high rates of ventricular pacing.&#x0D; Case description. A 61-year-old female patient was examined and treated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine from January 25 to January 27, 2022 at the department of surgical treatment of complex cardiac arrhythmias with a diagnosis of proximal complete atrioventricular block. A two-chamber pacemaker (Vitatron Q50A2) with a ventricular lead to stimulate the His bundle region (Medtronic 3830, 69 cm) was implanted to the patient with a special delivery system (C315HIS). At an X-ray operating room, 12 ECG leads from the electrophysiological station LabSystem Pro (Bard, USA) were connected to the patient to analyze the criteria for capturing the conduction system on stimulation during ventricular lead placement, and a diagnostic quadripolar electrode was inserted into the right ventricle to record the potential of the His bundle as an X-ray reference point. During placement of the ventricular lead in the area of the His bundle due to high pacing thresholds the decision was made to implement an alternative method of conduction system pacing – left bundle branch pacing through the interventricular septum. After gradual passage of the electrode through the septum, capture of the conduction system of the heart was achieved, although no clear potential of the left bundle was registered. The interval from stimulus to peak R wave in lead V6 was 68 ms, and the interval from stimulus to peak R wave in lead V1 was 110 ms. The difference between intervals was 42 ms, which indicated the criteria of nonselective capture of the left bundle branch, with stimulation thresholds below 1 V at a pulse length of 0.5 ms. In the postoperative period, the patient was evaluated for global longitudinal deformity of the left ventricle on constant ventricular stimulation, which was carried out according to standard methods using speckle-tracking echocardiography; no signs of dyssynchrony were found. Also, the location of the endocardial electrode in the middle segments of the interventricular septum on the right ventricular side was visualized and confirmed by performing B-mode transthoracic echocardiography with subcostal access.&#x0D; Conclusions. Left bundle branch pacing, like His bundle pacing, maintains electrical and mechanical synchrony of the left ventricle at lower pacing thresholds, greater amplitude of the sensitivity signal and lower risks of lead dislocation.

Comparative effects of left bundle branch area pacing, His bundle pacing, biventricular pacing in patients requiring cardiac resynchronization therapy: A network meta‐analysis

BackgroundThe comparative effects of different types of cardiac resynchronization therapy (CRT) delivered by biventricular pacing (BVP), His bundle pacing (HBP), and left bundle branch area pacing (LBBAP) remain inconclusive.HypothesisHBP and LBBAP may be advantageous over BVP for CRT.MethodsPubMed, Embase, Web of Science, and the Cochrane Library were systematically searched for studies that reported the effects after BVP, HBP, and LBBAP for CRT. The effects between groups were compared by a frequentist random‐effects network meta‐analysis (NMA), by which the mean differences (MDs) and 95% confidence intervals (CIs) were calculated.ResultsSix articles involving 389 patients remained for the final meta‐analysis. The mean follow‐up of these studies was 8.03 ± 3.15 months. LBBAP resulted in a greater improvement in LVEF% (MD = 7.17, 95% CI = 4.31 to 10.04), followed by HBP (MD = 4.06, 95% CI = 1.09 to 7.03) compared with BVP. HBP resulted in a narrower QRS duration (MD = 31.58 ms, 95% CI = 12.75 to 50.40), followed by LBBAP (MD = 27.40 ms, 95% CI = 10.81 to 43.99) compared with BVP. No significant differences of changes in LVEF improvement and QRS narrowing were observed between LBBAP and HBP. The pacing threshold of LBBAP was significantly lower than those of BVP and HBP.ConclusionThe NMA first found that LBBAP and HBP resulted in a greater LVEF improvement and a narrower QRS duration compared with BVP. Additionally, LBBAP resulted in similar clinical outcomes but with lower pacing thresholds, and may therefore offer advantages than does HBP for CRT.

Leadless pacemaker implantation sites confirmed by computed tomography and their parameters and complication rates.

Implantations of leadless pacemakers in the septum lower the risk of cardiac perforation. However, the relationship between the implantation site and the success rate, complication rate, and pacemaker parameters are not well-investigated. Patients who underwent leadless pacemaker implantation with postprocedural computed tomography (CT) between September 2017 and November 2020 were analyzed. Septum was targeted with fluoroscopic guidance with contrast injection. We divided patients into two groups based on the implantation site confirmed by CT: septal and non-septal, which included the anterior/posterior edge of the septum and free wall. We compared the complication rates and pacemaker parameters between the two groups. A total of 67 patients underwent CT after the procedure; among them, 28 were included in the septal group and 39 were included in the non-septal group. The non-septal group had significantly higher R wave amplitudes (6.5 ± 3.3vs. 9.7 ± 3.9mV, p=.001), lower pacing threshold (1.0 ± 0.94vs. 0.63 ± 0.45 V/0.24ms, p=.02), and higher pacing impedance (615 ± 114.1vs. 712.8 ± 181.3 ohms, p=.014) after the procedure compared to the septal group. Cardiac injuries were observed in four patients (one cardiac tamponade, one possible apical hematoma, two asymptomatic pericardial effusion), which were only observed in the non-septal group. Leadless pacemaker implantation may be technically challenging with substantial number of patients with non-septal implantation when assessed by CT. Septal implantation may have a lower risk of cardiac injury but may lead to inferior pacemaker parameters than non-septal implantation.

Abstract 8864: Left Bundle Branch Area Pacing is Non-Inferior to His Bundle Pacing in Achieving Physiologic Repolarization and T-Wave Memory Resolution

Introduction: We have previously reported that His bundle pacing (HBP) results in more physiologic ventricular repolarization as compared to conventional biventricular pacing. Left bundle branch area pacing (LBAP) is increasingly used as the preferred modality of physiologic pacing due to ease of implantation and low long-term pacing thresholds. LBAP and HBP are comparable in terms of achieving physiologic left ventricular (LV) depolarization. However, their effects on ventricular repolarization have not been assessed. Established ECG markers of arrhythmic risk can be used to compare ventricular repolarization across these two modalities of physiologic pacing. Hypothesis: LBAP is not inferior to HBP in its effects on ventricular repolarization and T-wave memory resolution. Methods: The following parameters were analyzed in patients with HBP (n = 34) and LBAP (n = 16) from post-implant ECGs: 1) QTc: QT corrected using Bazett’s formula in lead V5, and if not measurable, in V4 or V6 2) QTc Dispersion: Longest minus shortest QTc from precordial leads 3) Tp-Te Transmural: T-peak minus T-end in same lead as 1) 4) Tp-Te Total: Earliest T-peak minus latest T-end from all precordial leads 5) Tp Dispersion: Latest minus earliest T-peak from precordial leads To analyze T-wave memory resolution, QRS-T angles were compared using ECGs within 10 days of and after ≥ 25 days post implant. Results: See tables. Median time from implant to 1st ECG for both groups was ≤1 day. None of the repolarization parameters were significantly different in HBP vs. LBAP groups. Conclusion: All repolarization markers of arrhythmic risk were similar in HBP vs. LBAP. Both modalities showed similar effects on T-wave memory resolution. These data suggest that LBAP, in addition to achieving physiologic LV depolarization, is not inferior to HBP in achieving physiologic ventricular repolarization. These observations further support the increasing use of LBAP as the preferred modality for physiologic pacing.

Abstract 13251: Left Bundle Branchpacing Post-Atrioventricular Junction Ablation for Atrial Fibrillation: A Propensity Score Matching Analysis

Introduction: Although left bundle branch pacing (LBBP) has emerged as a novel pacing modality which can allow for safe atrioventricular junction (AVJ) ablation and lower pacing threshold compared to His bundle pacing (HBP), its long-term safety and efficacy in patients with atrial fibrillation (AF) is still unknown. Hypothesis: This study aimed to examine the long-term clinical feasibility, safety, and efficacy of LBBP in AF patients post-AVJ ablation and provide a balanced comparison of LBBP versus HBP. Methods: This study prospectively enrolled patients with AF and heart failure (HF) who underwent AVJ ablation and LBBP from July 2017 to December 2019. The control group patients were selected, by propensity score (PS) matching with a 1:1 ratio, among those HBP implantations performed in the years 2012-2019. Results: A total of 99 patients were enrolled in this study, with successful permanent LBBP post-AVJ ablation in 100% of patients (primary LBBP: 76; secondary LBBP: 23). Significantly improvements were observed in LVEF, tricuspid regurgitation, and mitral regurgitation at 1-year follow-up (p&lt;0.05). The proportion of patients whose acute threshold &lt;1 V@0.5ms was 97.9% and only one patient had an increase in threshold ≥1 V@0.5ms at 1-year follow-up. Further, patients with LBBP as an active-group was compared to patients with HBP (control-group) through PS matching with 170 successfully matched (PS-HBP, N=85; PS-LBBP, N=85). In the control-group, the success rate of permanent HBP was 81.9% (176/215), which was lower than that with LBBP (p&lt;0.001). No significant differences in clinical outcomes were observed between groups (p&gt;0.05), while lower thresholds, greater sensed R-wave amplitudes, and less complication were observed in PS-LBBP group (p&lt;0.05). Conclusions: LBBP is feasible, safe, and effective in AF and HF patients post-AVJ ablation, which has comparable clinical benefit, higher success rate, better pacing parameters, and less complication than HBP.

Left Bundle Branch Area Pacing for CRT in RBBB: Results from International LBBAP Collaborative-Study Group

Background: Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has limited efficacy in patients with heart failure (HF) and right bundle branch block (RBBB). Left bundle branch area pacing (LBBAP) has been reported as an alternative option for BVP-CRT. The aim of the study was to assess the feasibility and outcomes of LBBAP in patients with RBBB and indication for CRT in an international, multicenter, collaborative study. Methods: LBBAP was attempted in patients with LVEF<50%, RBBB and indications for CRT. Procedural, pacing and ECG parameters, clinical response (no HF hospitalization and improvement in NYHA class) and echocardiographic response (≥5% increase in ejection fraction) to LBBAP was assessed. Results: LBBAP was attempted in 121 patients and successful in 107 (88%). Age 74±12 years, female 25%, ischemic cardiomyopathy 49%, and ejection fraction 35±9%. QRS axis at baseline was normal in 24%, left axis 63%, right axis 13%. LBBAP threshold and R-wave amplitudes were 0.8±0.3V@0.5ms and 10±9mV at implant and remained stable during mean follow-up of 13±8 months. LBBAP resulted in significant narrowing of QRS duration (156±20ms to 150±24ms (p=0.01) with R-wave peak times in V6 of 85±16ms. LVEF improved from 35±9 to 43±12%(p<0.01). Clinical and echocardiographic response was observed in 60% and 61% of patients, respectively. Female gender and reduction in QRS duration with LBBAP were predictive of echocardiographic response and super-response. Conclusions: LBBAP is a feasible and safe alternative to BVP to deliver CRT in patients with RBBB. LBBAP provides low and stable pacing thresholds with favorable clinical and echocardiographic response.