Feasibility, Safety and Short-Term Follow-Up Of Defibrillator Lead at Left Bundle Branch Area Pacing Location: A Pilot Study.

BACKGROUND: Left bundle branch area pacing(LBBAP) has been increasingly adopted as an alternative modality for cardiac-resynchronization-therapy(CRT). The feasibility and safety of utilizing LBBAP lead to provide sensing of ventricular arrhythmia in patients receiving implantable cardioverter defibrillator(ICD) with CRT has been demonstrated recently OBJECTIVES: Aim of our study was to analyse the feasibility, safety and short-term follow-up of a traditional defibrillator lead at LBBAP location. METHODS: Patients who underwent successful LBBAP-defibrillator using DF-1/DF-4 lead and delivery catheter were included in the study. Defibrillation threshold(DFT) testing was performed after implantation to assess the ability of LBBAP defibrillator lead to sense and provide appropriate therapy for ventricular arrhythmia. RESULTS: Though the ICD-lead could be successfully deployed in LBB area in 7 out of 8 patients, it was repositioned to right-ventricle(RV) apex due to atrial-oversensing in one and cheesy-septum in another patient. Acute procedural success was 62.5%(5/8 patients). Mean age 62.6±21.6 years. Mean procedural duration 115.6±38.1 minutes with LBBAP defibrillator lead fluoroscopy duration of 10.6±3.5 minutes. Mean capture threshold 0.58±0.23V/0.4ms, sensed R-wave amplitude 9.6±2.2mV, pacing-impedance 560±145Ohms and shock impedance of 65.4±5.5Ohms. Defibrillation testing was successful in inducing ventricular-fibrillation and could be sensed and reverted promptly by the shock delivered through the lead. During mean follow-up of 3.8±2.2 months the pacing parameters remained stable. There were no episodes of inappropriate arrhythmia detection or therapy delivery during follow-up. CONCLUSION: LBBAP defibrillator is feasible, safe and effective during short-term follow-up. DFT-testing at the time of implantation will help in ensuring appropriate sensing and treatment of ventricular arrhythmias.

His bundle pacing versus left bundle branch area pacing in patients undergoing atrioventricular node ablation: A prospective and comparative study.

BACKGROUND: Pacemaker implantation combined with atrioventricular node ablation (AVNA) is a well-established strategy for uncontrolled atrial arrhythmias. Limited data are available regarding His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) in this setting. AIM: To compare the outcomes of HBP and LBBAP in patients undergoing pacemaker implantation combined with AVN in routine clinical practice. METHODS: We prospectively included all patients who underwent AVNA after successful conduction system pacing (CSP) in two hospitals between September 2017 and May 2023. The primary outcome was the 1-year composite of first episode of heart failure hospitalization, symptomatic atrioventricular node reconduction requiring a second AVNA procedure, lead revision or death from any cause. RESULTS: A total of 164 patients underwent AVNA following successful CSP (68 HBP and 96 LBBAP). Mean pacemaker implantation and AVNA procedure times were shorter in the LBBAP group than the HBP group (46±18 vs 59±23min; P<0.001 and 31±12 vs 43±22min, respectively; P<0.001). Complete atrioventricular block was more frequently obtained in the LBBAP group (88/96 patients [92%] vs 54/68 patients [79%]; P=0.04). One-year freedom from the composite outcome was more frequent in the LBBAP group (89.7% vs 72.9%; hazard ratio 0.32, 95% confidence interval 0.14-0.72; P=0.01). The strategy was similarly effective in both groups with a significant improvement in NYHA class and left ventricular ejection fraction. A secondary pacing threshold elevation >1V occurred only in the HBP group (11%). CONCLUSION: In this prospective, comparative study, LBBAP provided better 1-year outcomes than HBP.

Left Bundle Branch Area Pacing With or Without Conduction System Capture in Heart Failure Models.

BACKGROUND: Left bundle branch area pacing includes left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP), which is effective in patients with dyssynchronous heart failure (DHF). However, the basic mechanisms are unknown. OBJECTIVES: This study aimed to compare LBBP with LVSP and explore potential mechanisms underlying the better clinical outcomes of LBBP. METHODS: A total of 24 beagles were assigned to the following groups: 1) control group; 2) DHF group, left bundle branch ablation followed by 6 weeks of AOO pacing at 200 ppm; 3) LBBP group, DHF for 3 weeks followed by 3 weeks of DOO pacing at 200 ppm; and 4) LVSP with the same interventions in the LBBP group. Metrics of electrocardiogram, echocardiography, hemodynamics, and expression of left ventricular proteins were evaluated. RESULTS: Compared with LVSP, LBBP had better peak strain dispersion (44.67 ± 1.75 ms vs 55.50 ± 4.85 ms; P < 0.001) and hemodynamic effect (dP/dtmax improvement: 27.16% ± 7.79% vs 11.37% ± 4.73%; P < 0.001), whereas no significant differences in cardiac function were shown. The altered expressions of proteins in the lateral wall vs septum in the DHF group were partially reversed by LBBP and LVSP, which was associated with the contraction and adhesion process, separately. CONCLUSIONS: The animal study demonstrated that LBBP offered better mechanical synchrony and improved hemodynamics than LVSP, which might be explained by the reversed expression of contraction proteins. These results supported the potential superiority of left bundle branch area pacing with the capture of the conduction system in DHF model.

Clinical impact and predictors of periprocedural myocardial injury among patients undergoing left bundle branch area pacing.

BACKGROUND: The clinical impact of Periprocedural myocardial injury (PMI) in patients undergoing permanent pacemaker implantation with Left Bundle Branch Area Pacing (LBBAP) is unknown. METHODS: 130 patients undergoing LBBAP from January 2020 to June 2021 and completing 12 months follow up were enrolled to assess the impact of PMI on composite clinical outcome (CCO) defined as any of the following: all-cause death, hospitalization for heart failure (HHF), hospitalization for acute coronary syndrome (ACS) and ventricular arrhythmias (VAs). High sensitivity Troponin T (HsTnT) was measured up to 24-h after intervention to identify the peak HsTnT values. PMI was defined as increased peak HsTnT values at least > 99th percentile of the upper reference limit (URL: 15 pg/ml) in patients with normal baseline values. RESULTS: PMI occurred in 72 of 130 patients (55%). ROC analysis yielded a post-procedural peak HsTnT cutoff of fourfold the URL for predicting the CCO (AUC: 0.692; p = 0.023; sensitivity 73% and specificity 71%). Of the enrolled patients, 20% (n = 26) had peak HsTnT > fourfold the URL. Patients with peak HsTnT > fourfold the URL exhibited a higher incidence of the CCO than patients with peak HsTnT ≤ fourfold the URL (31% vs. 10%; p = 0.005), driven by more frequent hospitalizations for ACS (15% vs. 3%; p = 0.010). Multiple (> 2) lead repositions attempts, the use of septography and stylet-driven leads were independent predictors of higher risk of PMI with peak HsTnT > fourfold the URL. CONCLUSIONS: PMI seems common among patients undergoing LBBAP and may be associated with an increased risk of clinical outcomes in case of more pronounced (peak HsTnT > fourfold the URL) myocardial damage occurring during the procedure.

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.

Current role of Conduction System Pacing in Patients Requiring Permanent Pacing.

His bundle pacing (HBP) and left bundle branch pacing (LBBP) are novel methods of pacing directly pacing the cardiac conduction system. HBP while developed more than two decades ago, only recently moved into the clinical mainstream. In contrast to conventional cardiac pacing, conduction system pacing including HBP and LBBP utilizes the native electrical system of the heart to rapidly disseminate the electrical impulse and generate a more synchronous ventricular contraction. Widespread adoption of conduction system pacing has resulted in a wealth of observational data, registries, and some early randomized controlled clinical trials. While much remains to be learned about conduction system pacing and its role in electrophysiology, data available thus far is very promising. In this review of conduction system pacing, the authors review the emergence of conduction system pacing and its contemporary role in patients requiring permanent cardiac pacing.

Sex Differences in Left Bundle Branch Area Pacing Versus Biventricular Pacing for Cardiac Resynchronization Therapy.

BACKGROUND: Women respond more favorably to biventricular pacing (BIVP) than men. Sex differences in atrioventricular and interventricular conduction have been described in BIVP studies. Left bundle branch area pacing (LBBAP) offers advantages due to direct capture of the conduction system. We hypothesized that men could respond better to LBBAP than BIVP. OBJECTIVES: This study aims to describe the sex differences in response to LBBAP vs BIVP as the initial cardiac resynchronization therapy (CRT). METHODS: In this multicenter prospective registry, we included patients with left ventricular ejection fraction ≤35% and left bundle branch block or a left ventricular ejection fraction ≤40% with an expected right ventricular pacing exceeding 40% undergoing initial CRT with LBBAP or BIVP. The composite primary outcome was heart failure-related hospitalization and all-cause mortality. The primary safety outcome included all procedure-related complications. RESULTS: There was no significant difference in the primary outcome when comparing men and women receiving LBBAP (P = 0.46), whereas the primary outcome was less frequent in women in the BIVP group than men treated with BIVP (P = 0.03). The primary outcome occurred less frequently in men undergoing LBBAP (29.9%) compared to those treated with BIVP (46.5%) (P = 0.004). In women, the incidence of the primary endpoint was 24.14% in the LBBAP group and 36.2% in the BIVP group; however, this difference was not statistically significant (P = 0.23). Complication rates remained consistent across all groups. CONCLUSIONS: Men and women undergoing LBBAP for CRT had similar clinical outcomes. Men undergoing LBBAP showed a lower risk of heart failure-related hospitalizations and all-cause mortality compared to men undergoing BIVP, whereas there was no difference between LBBAP and BIVP in women.

Left Bundle Branch Area Pacing to Overcome Coronary Sinus Anatomy-Related Technical Problems Encountered during Implantation of Biventricular CRT-A Case Report.

The results of clinical trials show that up to one-third of patients who are eligible for cardiac resynchronization therapy (CRT) do not benefit from biventricular pacing. The reasons vary, including technical problems related to left ventricle pacing lead placement in the appropriate branch of the coronary sinus. Herein, we present a case report of a patient with heart failure with reduced ejection fraction and left bundle branch block, in whom a poor coronary sinus bed made implantation of classic biventricular CRT impossible, but in whom, alternatively, rescue-performed left bundle branch area pacing allowed effective electrical and mechanical cardiac resynchronization. The report confirms that left bundle branch area pacing may be a rational alternative in such cases.

Is conduction system pacing a panacea for pacemaker therapy?

INTRODUCTION: While supported by robust evidence and decades of clinical experience, right ventricular apical pacing for bradycardia is associated with a risk of progressive left ventricular dysfunction. Cardiac resynchronization therapy for heart failure with reduced ejection fraction can result in limited electrical resynchronization due to anatomical constraints and epicardial stimulation. In both settings, directly stimulating the conduction system below the atrio-ventricular node (either the bundle of His or the left bundle branch area) has potential to overcome these limitations. Conduction system pacing has met with considerable enthusiasm in view of the more physiological electrical conduction pattern, is rapidly becoming the preferred option of pacing for bradycardia, and is gaining momentum as an alternative to conventional biventricular pacing. AREAS COVERED: This article provides a review of the current efficacy and safety data for both people requiring treatment for bradycardia and the management of heart failure with conduction delay and discusses the possible future roles for conduction system pacing in routine clinical practice. EXPERT OPINION: Conduction system pacing might be the holy grail of pacemaker therapy without the disadvantages of current approaches. However, hypothesis and enthusiasm are no match for robust data, demonstrating at least equivalent efficacy and safety to standard approaches.

A case report of right ventricular defibrillator and left bundle branch area leads placement and atrioventricular node ablation with chronic right ventricular thrombus.

Despite lack of concrete evidence, right ventricular thrombus is generally considered to be a contraindication for intracardiac lead placement. We present a case of successful placement of a right ventricular defibrillator lead and left bundle branch pacing lead and atrioventricular node ablation in a patient with chronic right ventricle thrombus.

Closed loop stimulation in left bundle branch area pacing.

INTRODUCTION: Closed Loop Stimulation (CLS) is a rate-responsive algorithm that adjusts heart rate (HR) based on changes in intracardiac impedance measured from the right ventricle lead. However, the use of CLS in conduction system pacing has not been investigated. In this retrospective study, we aimed to assess whether CLS with left bundle branch area pacing (LBBAP) can generate an appropriate distribution of HR in daily life. METHODS AND RESULTS: Our study included 24 patients with CLS pacing and chronotropic incompetence, comparing them with 19 patients receiving DDD pacing, all with LBBAP. Cumulative HR distribution charts were generated using data from a single device interrogation with a minimum follow-up period of 30 days. In DDD-CLS mode, there was a higher percentage of atrial pacing compared to DDD mode (median 58% [interquartile range 29%-83%] vs. 13% [10%-26%], p = .001), and CLS-paced beats were present across all frequency bins. The distribution of beats between the groups was similar (p = .643), resulting in comparable mean HR (72 bpm [70-77] vs. 73 bpm [65-75], p = .615). CONCLUSIONS: In the context of LBBAP, CLS effectively modulates pacing rates over a wide frequency range. This lead position does not adversely affect the rate-responsive performance of the algorithm.

Single-center experience of efficacy and safety of atrioventricular node ablation after left bundle branch area pacing for the management of atrial fibrillation.

BACKGROUND: Atrioventricular node ablation (AVNA) with permanent pacing is an effective treatment of symptomatic atrial fibrillation (AF). Left bundle branch area pacing (LBBAP) prevents cardiac dyssynchrony associated with right ventricular pacing and could prevent worsening of heart failure (HF). METHODS: In this retrospective monocentric study, all patients who received AVNA procedure with LBBAP were consecutively included. AVNA procedure data, electrical and echocardiographic parameters at 6 months, and clinical outcomes at 1 year were studied and compared to a matched cohort of patients who received AVNA procedure with conventional pacing between 2010 and 2023. RESULTS: Seventy-five AVNA procedures associated with LBBAP were studied. AVNA in this context was feasible, with a success rate of 98.7% at first ablation, and safe without any complications. There was no threshold rise at follow-up. At 1 year, 6 (8%) patients were hospitalized for HF and 2 (2.7%) were deceased. Patients had a significant improvement in NYHA class and left ventricular ejection fraction (LVEF) (P ≤ 0.0001). When compared to a matched cohort of patients with AVNA and conventional pacing, AVNA data and pacing complications rates were similar. Patients with LBBAP had a better improvement of LVEF (+5.27 ± 9.62% vs. -0.48 ± 14%, P = 0.01), and a lower 1-year rate of composite outcome of hospitalization for HF or death (HR 0.39, 95% CI: 0.16-0.95, P = 0.037), significant on survival analysis (log-rank P-value = 0.03). CONCLUSION: AVNA with LBBAP in patients with symptomatic AF is feasible, safe, and efficient. Hospitalization for HF or death rate was significantly lower and LVEF improvement was greater.

Cardiac resynchronization therapy (CRT) nonresponders in the contemporary era: A state-of-the-art review.

In the 2000s, cardiac resynchronization therapy (CRT) became a revolutionary treatment of heart failure with reduced left ventricular ejection fraction (HFrEF) and wide QRS. However, about one-third of CRT recipients do not show a favorable response. This review of the current literature aims to better define the concept of CRT response/nonresponse. The diagnosis of CRT nonresponder should be viewed as a continuum, and it cannot rely solely on a single parameter. Moreover, baseline features of some patients might predict an unfavorable response. A strong collaboration between heart failure specialists and electrophysiologists is key to overcoming this challenge with multiple strategies. In the contemporary era, new pacing modalities, such as His-bundle pacing and left bundle branch area pacing, represent a promising alternative to CRT. Observational studies have demonstrated their potential; however, several limitations should be addressed. Large randomized controlled trials are needed to prove their efficacy in HFrEF with electromechanical dyssynchrony.

Transvenous extraction of conduction system pacing leads: An international multicenter (TECSPAM) study.

BACKGROUND: Conduction system pacing (CSP) by His bundle pacing or left bundle branch area pacing (LBBAP) is incorporated into Heart Rhythm Society guidelines for the management of bradycardia and cardiac resynchronization therapy. Despite increasing adoption with both lumenless leads and stylet-driven leads, concerns regarding the feasibility and safety of the extraction of CSP leads remain. OBJECTIVE: The aim of the study was to report on the safety, feasibility, and clinical outcomes of the extraction of CSP leads. METHODS: Patients undergoing the extraction of CSP leads from 10 international centers were enrolled in this retrospective study. Data regarding indications, lead location, lead type, extraction tools, procedural success, complications, and reimplantation in the conduction system were collected. RESULTS: Overall, 341 patients (age 69 ± 15 years; female 34%; cardiomyopathy 46%; lead dwell time 22 ± 26 months) underwent the extraction of 224 His bundle pacing and 117 LBBAP leads (lumenless leads 321; stylet-driven leads 20). Complete procedural success was achieved in 338 (99%), while clinical success was 100% with retained distal fragments in 3 patients (1%). Among patients with a lead dwell time of >6 months (6-193 months; n = 226), manual extraction was successful in 198 (87%), mechanical tools in 22 (10%), and laser in 6 (3%). Femoral tools were necessary in 3 patients. Minor complications occurred in 7 patients (2.1%). CSP reimplantation was successful in 233 of 244 patients attempted (95%). CONCLUSION: The overall success rates of the extraction of CSP leads were very high (although the LBBAP lead dwell time was <3 years), with a low need for extraction tools and minimal complication. Reimplantation in the conduction system is feasible and safe.

Is Conduction System Pacing a Valuable Alternative to Biventricular Pacing for Cardiac Resynchronization Therapy?

Cardiac resynchronization therapy (CRT) significantly improves clinical outcomes in patients with ventricular systolic dysfunction and dyssynchrony. Biventricular pacing (BVP) has a class IA recommendation for patients with symptomatic heart failure with reduced ejection fraction (HFrEF) and left bundle branch block (LBBB). However, approximately 30% of patients have a poor therapeutic response and do not achieve real clinical benefit. Pre-implant imaging, together with tailored programming and dedicated device algorithms, have been proposed as possible tools to improve success rate but have shown inconsistent results. Over the last few years, conduction system pacing (CSP) is becoming a real and attractive alternative to standard BVP as it can restore narrow QRS in patients with bundle branch block (BBB) by stimulating and recruiting the cardiac conduction system, thus ensuring true resynchronization. It includes His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). Preliminary data coming from small single-center experiences are very promising and have laid the basis for currently ongoing randomized controlled trials comparing CSP with BVP. The purpose of this review is to delve into the emerging role of CSP as an alternative method of achieving CRT. After framing CSP in a historical perspective, the pathophysiological rationale and available clinical evidence will be examined, and crucial technical aspects will be discussed. Finally, evidence gaps and future perspectives on CSP as a technique of choice to deliver CRT will be summarized.

Left bundle branch pacing set to outshine biventricular pacing for cardiac resynchronization therapy?

The deleterious effects of long-term right ventricular pacing necessitated the search for alternative pacing sites which could prevent or alleviate pacing-induced cardiomyopathy. Until recently, biventricular pacing (BiVP) was the only modality which could mitigate or prevent pacing induced dysfunction. Further, BiVP could resynchronize the baseline electromechanical dssynchrony in heart failure and improve outcomes. However, the high non-response rate of around 20%-30% remains a major limitation. This non-response has been largely attributable to the direct non-physiological stimulation of the left ventricular myocardium bypassing the conduction system. To overcome this limitation, the concept of conduction system pacing (CSP) came up. Despite initial success of the first CSP via His bundle pacing (HBP), certain drawbacks including lead instability and dislodgements, steep learning curve and rapid battery depletion on many occasions prevented its widespread use for cardiac resynchronization therapy (CRT). Subsequently, CSP via left bundle branch-area pacing (LBBP) was developed in 2018, which over the last few years has shown efficacy comparable to BiVP-CRT in small observational studies. Further, its safety has also been well established and is largely free of the pitfalls of the HBP-CRT. In the recent metanalysis by Yasmin et al, comprising of 6 studies with 389 participants, LBBP-CRT was superior to BiVP-CRT in terms of QRS duration, left ventricular ejection fraction, cardiac chamber dimensions, lead thresholds, and functional status amongst heart failure patients with left bundle branch block. However, there are important limitations of the study including the small overall numbers, inclusion of only a single small randomized controlled trial (RCT) and a small follow-up duration. Further, the entire study population analyzed was from China which makes generalizability a concern. Despite the concerns, the meta-analysis adds to the growing body of evidence demonstrating the efficacy of LBBP-CRT. At this stage, one must acknowledge that the fact that still our opinions on this technique are largely based on observational data and there is a dire need for larger RCTs to ascertain the position of LBBP-CRT in management of heart failure patients with left bundle branch block.

Left bundle branch area pacing using a stylet-driven, retractable-helix lead: Short-term results from a prospective multicenter IDE trial (the BIO-CONDUCT study).

BACKGROUND: Left bundle branch area pacing (LBBAP) has swiftly emerged as a safe and effective alternative to right ventricular pacing. Limited data exist on the use of retractable-helix, stylet-driven leads for LBBAP. OBJECTIVE: The objective of this study was to prospectively evaluate the performance and safety of a stylet-driven pacing lead in a rigorously controlled multicenter trial to support US market application. METHODS: A multicenter, prospective, nonrandomized trial enrolled patients with standard pacing indications. Implant procedure and lead data, including threshold, sensing, impedance, and capture type, were collected through 3 months. Primary end points were freedom from LBBAP lead-related serious complications through 3 months and LBBAP implant success according to prespecified criteria. A blinded clinical events committee adjudicated all potential end point complications. RESULTS: A total of 186 patients were included from 14 US sites. LBBAP implants were successful in 95.7% (178 of 186; 95% confidence interval 91.7%-98.1%; P < .0001 for comparison to the performance goal of 88%). Through the 3-month follow-up visit, 3 patients (1.7%) experienced a serious LBBAP complication (all lead dislodgments), resulting in a LBBAP lead-related complication-free rate of 98.3%. A total of 13 patients (7.8%) experienced any system- or procedure-related complication. The mean threshold was 0.89 V at 0.4 ms, the sensing value was 10.8 mV, and impedance was 608 Ω. CONCLUSION: The short-term results from this prospective trial demonstrate both high implant success and freedom from LBBAP lead-related complications using this stylet-driven retractable helix lead. This trial supports the safety, use, and effectiveness of stylet-driven leads for performing contemporary physiologic pacing.

New-onset atrial high-rate episodes in left bundle branch area pacing versus right ventricular pacing for patients with atrioventricular block.

BACKGROUND: Left bundle branch area pacing (LBBAP) demonstrated beneficial effects on clinical outcomes. Comparative data on the risk of atrial high-rate episodes (AHREs) between LBBAP and right ventricular pacing (RVP) are lacking. AIMS: This study aimed to investigate whether LBBAP can reduce the risk of new-onset AHREs compared with RVP in patients with atrioventricular block (AVB). METHODS: We enrolled 175 consecutive AVB patients with no history of atrial fibrillation undergoing dual-chamber pacemaker implantation (LBBAP or RVP). Propensity score matching for baseline characteristics yielded 43 matched pairs. The primary outcome was new-onset AHREs detected on a scheduled device follow-up. Changes in echocardiographic measurements were also compared between the groups. RESULTS: New-onset AHREs occurred in 42 (24.0%) of all enrolled patients (follow-up 14.1 [7.5] months) and the incidence of new-onset AHREs in the LBBAP group was lower than in the RVP group (19.8% vs. 34.7%; P = 0.04). After propensity score matching, LBBAP still resulted in a lower incidence of new-onset AHREs (11.6% vs. 32.6%; P = 0.02), and a lower hazard ratio for new-onset AHREs compared with RVP (HR, 0.274; 95% CI, 0.113-0.692). At 1 year, LBBAP achieved preserved left ventricular ejection fraction (LVEF) (63.0 [3.2]% to 63.1 [3.1]%; P = 0.56), while RVP resulted in reduced LVEF (63.4 [4.9]% to 60.5 [7.3]%; P = 0.01]). Changes in LVEF were significantly different between the 2 groups (by 2.6% [0.2 to 5.0]%; P = 0.03). CONCLUSION: LBBAP demonstrated a reduced risk of new-onset AHREs compared with RVP in patients with AVB.

Left bundle branch area pacing improves right ventricular function and synchrony.

BACKGROUND: The impact of left bundle branch area pacing (LBBAP) on right ventricular (RV) function and tricuspid regurgitation (TR) remains unclear. OBJECTIVE: We aimed to assess the long-term effects of LBBAP on RV performance and on TR. METHODS: RV function was evaluated using RV free wall strain, tricuspid annular plane systolic excursion, fractional area changing, and systolic velocity of the lateral tricuspid annulus. The presence of reverse septal flash (RSF) and basal bulge (BB) was used to assess RV motion pattern. The distance between the lead entry site on the interventricular septum and the septal leaflet of the tricuspid annulus (lead-TV distance) was measured. RESULTS: The analysis included 122 subjects [62 men (50.8%); mean age 76.5 ± 11.4 years] with a median follow-up of 21 months (18-24.5 months). During follow-up, RV free wall strain improved significantly (15.2 ± 5.8 vs 16.4 ± 5.5; P < .001) while tricuspid annular plane systolic excursion, systolic, and fractional area changing remained unchanged. Left ventricular ejection fraction was an independent predictor of improved RV function (B = 3.51; 95% confidence interval 1.39-8.9; P = .01). With LBBAP, RSF disappeared in 22 of 23 patients (96%) and BB in 15 of 22 patients (68%) in whom RSF and BB were present at baseline, respectively. RV function improvement was significantly higher when RSF was present at baseline (14 patients vs 11 patients; P = .02). At follow-up, no significant deterioration in TR occurred for the overall group. However, a lead-TV distance of <24.5 mm was associated with TR progression. CONCLUSION: LBBAP has a favorable impact on RV function. A basal LBBAP position is associated with worsening TR.

Strength-duration curves for left bundle branch area pacing.

BACKGROUND: Despite growing clinical use of left bundle branch pacing (LBBP), data regarding the fundamentals of this pacing modality, including chronaxie and rheobase, are scarce. OBJECTIVE: The purpose of this study was to calculate strength-duration curves with chronaxie and rheobase values for LBBP and left ventricular septal pacing (LVSP), and to analyze battery current drain and presence of selective LBBP at very short pulse duration (PD). METHODS: A group of 141 patients with permanent LBBP were studied. LBBP and LVSP capture thresholds were assessed at 6 different PDs to calculate the strength-duration curves. Battery current drain at these PDs and presence of selective LBBP were determined. For comparison of strength-duration curves between His-bundle pacing (HBP) and LBBP, source data from our previous work based on 127 patients with HBP were obtained. RESULTS: The chronaxies for LBBP and LVSP were very similar (0.38 vs 0.39 ms), and the rheobases were identical (0.27 V). The chronaxie for LBBP was lower than for HBP (0.38 vs 0.53 ms; P <.001), whereas rheobases were similar (0.27 vs 0.26 V). A narrow zone of selective capture was present in 19% and 41% of patients at PD of 0.06 and 0.03 ms, respectively. When pacing with the safety margin of +1 V, the lowest battery current drain was achieved with PD of 0.2 ms. CONCLUSION: The obtained strength-duration curves for LBBP and LVSP provide insights to optimal programming of left bundle branch area pacing devices with regard to PD, voltage amplitude, battery longevity, and selective capture.