Cardiac Conduction System Pacing: A Comprehensive Update

Electrocardiographic predictors of clinical outcomes in nonischemic cardiomyopathy patients with left bundle branch area pacing cardiac resynchronization therapy

BACKGROUND

Paced QRS morphology may vary during left bundle branch area pacing (LBBAP) per the pacing location. It remains unclear whether electrocardiographic changes observed during LBBAP can predict clinical outcomes.

OBJECTIVE

We aimed to assess correlation between characteristics of paced QRS on the electrocardiogram and clinical outcomes in heart failure patients with nonischemic cardiomyopathy.

METHODS

Of 79 consecutive heart failure patients receiving LBBAP, 59 patients were included in this prospective study after exclusions. LBBAP was performed using Medtronic 3830 lead. Patients were assigned to various groups on the basis of paced QRS morphology in lead V1 (qR and Qr), QRS axis (normal, left, or right), and V6 R-wave peak time (RWPT, ≤80 ms or >80 ms) to compare echocardiographic outcomes.

RESULTS

RWPT was significantly shorter (75.7 ± 17.5 ms vs 85.3 ± 11.3 ms; P = .014), transition during threshold testing was more commonly observed (81.5% vs 53%; P = .02), and improvement in left ventricular ejection fraction (LVEF) was significantly greater in the qR group (21.4% ± 6.4% vs 16.4% ± 8.3%; P = .013) compared with the Qr group. RWPT or LVEF did not differ in patients with different paced QRS axis (P > .05). Whereas qR morphology and presence of transition during threshold testing independently predicted LVEF improvement, RWPT lacked predictive value. Nonresponders had greater incidence of loss of R' (P = .009) and prolonged RWPT (P = .003) on follow-up compared with average responders and superresponders.

CONCLUSION

Paced qR morphology and transition during threshold testing predicted greater improvement in LVEF, whereas RWPT lacked predictive value. Loss of terminal R in lead V1 and prolongation of RWPT on follow-up prognosticated nonresponse to LBBAP.

Echocardiographic imaging in patients with conduction system pacing

Conduction system pacing (CSP), encompassing His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), revolutionizes cardiac pacing, allowing a more physiological left ventricular activation than conventional right ventricular (RV) pacing through electrode placed in RV apex, interventricular septum or right ventricular outflow tract. Echocardiography plays a pivotal role in patient assessment, primarily by measuring left ventricular ejection fraction (LVEF) to determine the pacing strategy in alignment with current guidelines. Clinical data, simulations and ongoing trials on CSP explore CSP viability across various LVEF conditions. CSP is supposed to defer pacing-induced cardiomyopathy (PiCM) associated with conventional right ventricular pacing (RVP). This paper aims to review the current literature regarding the use of echocardiography in CSP. Images from our experience in the echocardiographic lab were used throughout this document to show our proposals of imaging in CSP. Echocardiography may help to determine lead localization within the interventricular septum (IVS), customizing pacing to individual anatomy and electromechanical indices (like atro-ventricular delay) and evaluates often-overlooked valvular function, a potential PiCM contributor. Three-dimensional (3-D) echocardiography widens the knowledge of lead localization and valvular dysfunction, as well as dyssynchrony assessment. Dyssynchrony, crucial both to resynchronization per se and physiological stimulation is quantified via echocardiography, especially using speckle-tracking imaging. Baseline LVEF and follow-up observation of CSP effects: early in Global Longitudinal Strain (GLS), afterwards in LV volumes and LVEF may improve the future proper qualification of patients. Limited left atrial (LA) and right atrial (RA) strain assessments hold potential in the CSP qualification and response assessment context. Echocardiography complements other imaging modalities for comprehensive patient evaluation. Echocardiography is integral in the CSP clinical use, from patient selection (by showing subtle changes in myocardial function) to post-procedure follow-up (tricuspid regurgitation, LV and RV function, leads and synchrony assessment). GLS, assessed by speckle tracking imaging and profound 2D and 3D (lead placement, septum morphology and global heart function under CSP) analyses show promise in CSP outcome assessment, though standardization is needed.

Establishing a left bundle branch area pacing program: Results from a high-volume pacing center

INTRODUCTION AND OBJECTIVES

Left bundle branch area pacing (LBBAP) is a technique suitable for treating both symptomatic bradycardia and cardiac resynchronization therapy (CRT). Our study aims to describe the first experience of LBBAP in a high-volume cardiac implantable electronic device (CIED) center.

METHODS

This prospective single-center observational registry included consecutive patients who underwent pacemaker implantation with LBBAP technique for sinus node disease, bradycardia and CRT indications between January 2023 and January 2024. Procedural data, outcomes, and lead parameters were recorded at hospital discharge, at one and six months of follow-up.

RESULTS

A total of 164 consecutive patients undergoing LBBAP implantation were included, of whom 142 had a stylet-driven lead. LLBAP was achieved in 94.5% patients. Average QRS duration was 139.8±33.4 ms. Complete atrioventricular block was the most common indication (42.7%). CRT was performed in 24 (14.5%) patients. Mean procedural duration was 82.7±24.4 min and mean fluoroscopy time was 13.7±7.1 min. Average LVAT was 78.8±8.7 ms and paced QRS width 114.8±14.4 ms. Median acute R-wave amplitude was 14.0 mV, pacing threshold was 0.5 V and impedance 526 Ω. No relevant per-operative complications occurred. After one month of follow-up, median pacing threshold had significantly increased to 0.75 V (p<0.001) while R-wave amplitude and impedance remained unchanged (p=0.242 and p=0.101 respectively). During follow-up, no changes occurred in the evaluated parameters. Loss of left bundle branch capture occurred in five patients and macro-dislodgement in 2.

CONCLUSION

LBBAP is a feasible pacing technique which reduces QRS duration and improves LV synchrony and can be adopted at most centers, with favorable success rates and safety profile.

Echocardiographic response from left bundle branch area pacing optimized cardiac resynchronization therapy (LOT-CRT) vs traditional CRT

BACKGROUND

Traditional cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) may be less effective in patients with nonspecific intraventricular conduction delay (NIVCD). Left bundle branch area pacing (LBBAP) combined with left ventricular (LV) coronary venous lead pacing (LOT-CRT) may be more effective in these patients.

OBJECTIVE

We assessed the echocardiographic response of LOT-CRT in patients with left bundle branch block (LBBB) or NIVCD and compared it with a propensity-matched BVP cohort.

METHODS

Patients with conventional CRT indications and preferentially NIVCD were recruited. Echocardiographic parameters, including absolute percentage change in LV ejection fraction (LVEF) and relative percentage change in LV end-systolic volume (LVESV), were evaluated at implantation and 6-month follow-up. The BVP cohort was from an independent study, selected using 1:1 propensity-matching. LOT-CRT patients were subclassified into "successful LOT-CRT" (LBBAP; presence of r' in electrode electrocardiography [ECG] V1) and "deep septal optimized therapy" (DOT-CRT) (functional deep septal capture).

RESULTS

LOT-CRT patients (N = 34; age 64 years, women 38%, NIVCD 47%, LBBB 53%, implantable cardiac monitor 21%, QRSd 175 ms, and LVEF 27.6%) had significantly greater LVEF improvement (16.1% vs 6.1%; P <.01) and LVESV reduction (-43.5% vs -20.9%; P <.01) compared with BVP patients. After adjusting for baseline characteristics, LOT-CRT patients still had significantly greater LVEF improvement (7.5%; P <.01) and LVESV reduction (18.4%; P <.01) than BVP patients. The response was consistent across LBBB and NIVCD subgroups. LOT-CRT patients with QRS ≥ 171 ms showed greater benefit (P = .04; both LVEF and LVESV). No significant differences were observed between successful LOT-CRT and DOT-CRT.

CONCLUSION

LOT-CRT resulted in superior LVEF and LVESV improvements compared with BVP in NIVCD and LBBB patients and enhanced CRT response.

Evolving Indications, Challenges, and Advances in Cardiac Resynchronization Therapy for Heart Failure

Cardiac resynchronization therapy (CRT) via biventricular pacing has markedly improved heart failure outcomes over the past two decades. However, some patients show no clinical improvement or evidence of reverse remodeling following device implantation. Challenges include suboptimal patient selection, limitations in the characterization of conduction disease (especially nonspecific interventricular conduction delays), procedural constraints, inappropriate device programming, and delayed referral. Moreover, there remains no formal consensus on evaluating and characterizing CRT efficacy. Underutilization persists among women and minoritized racial and ethnic groups. Targeted research addressing unmet needs has led to evolving guideline indications. Novel electrocardiographic and imaging techniques are continually being developed to improve patient selection and alternate pacing strategies have emerged. Conduction system pacing may allow for a more physiologic approach to CRT. Observational studies and small clinical trials have shown comparable or superior efficacy of conduction system pacing over traditional biventricular pacing; however, more studies are needed. LAY SUMMARY: Cardiac resynchronization therapy via biventricular pacing has transformed heart failure management over the past two decades. This review examines persistent challenges in clinical practice and evolving guideline recommendations. Key issues, including refining patient selection, better characterizing conduction abnormalities, and optimizing device programming, were highlighted. Emerging evidence suggests conduction system pacing as a physiologic alternative to biventricular pacing, with early studies showing promising outcomes. However, rigorous clinical trials are needed to confirm these findings and guide future practice. Advancing CRT necessitates continued innovation and strategies to improve equity and access across diverse populations.

Early outcomes of left bundle branch area pacing in children

OBJECTIVE

Left bundle branch area pacing is a recent technique gaining rapid acceptance due to its broader target area and excellent electrical parameters. The aim of this study was to demonstrate the feasibility of left bundle branch area pacing in children and share short-term results.

MATERIALS AND METHODS

A retrospective study conducted at a single centre between December 2021 and April 2024 involved 19 children who underwent left bundle branch area pacing using Select Secure leads. The study included echocardiographic evaluations, pacing parameters, and follow-up outcomes.

RESULTS

The cohort comprised 10 males and 9 females. Median age was seven years (range 2-18), and median weight was 38 kg (range 13-56). All patients had complete atrioventricular block, with seven having isolated congenital complete atrioventricular block and 12 postoperative complete atrioventricular block. In nine patients, transitioning from epicardial to endocardial pacing resulted in ventricular dysfunction due to chronic right ventricular pacing. The remaining patients received left bundle branch area pacing initially. One patient underwent implantation in a septal position close to the left bundle due to left bundle branch area pacing infeasibility. The median post-procedure QRS duration was 92 msec (range 80-117). Median R wave amplitude, threshold, and impedance values were 14.7 mV (range 13.3-16.8), 0.7 mV (range 0.5-1.1), and 728 ohms (range 640-762), respectively. Atrioventricular (DDD mode) leads were implanted in 10 patients, and ventricular leads (VVIR mode) were implanted in nine patients. Median fluoroscopy dose was 18.7 mGy (13.5-34.52).

CONCLUSION

Left bundle branch area pacing can be safely conducted in paediatric patients exhibiting a narrow QRS duration and stable pacing parameters.

Cardiac Implantable Electronic Devices in Ischemic Cardiomyopathy

This review discusses the range of device therapy for ischemic cardiomyopathy (ICM). This article will review the primary data supporting guideline indications for cardiac implantable electronic devices in patients with ICM, with a focus on primary/secondary prevention transvenous implantable cardioverter defibrillators (ICDs), cardiac resynchronization therapy, and subcutaneous/extravascular ICDs. In addition, this review discusses emerging device therapy for ICM including left bundle area pacing/defibrillation, cardiac contractility modulation and baroflex activation therapy. Device therapy for ICM continues to evolve to incorporate diverse modalities across the spectrum from prevention of sudden cardiac death to modifying cardiac remodeling and recovery.

Novel cardiac CT method for identifying the atrioventricular conduction axis by anatomic landmarks

BACKGROUND

Understanding the conduction axis location aids in avoiding iatrogenic damage and guiding targeted heart rhythm therapy.

OBJECTIVE

Cardiac structures visible with clinical imaging have been demonstrated to correlate with variability in the conduction system course. We aimed to standardize and assess the reproducibility of predicting the location of the atrioventricular conduction axis by cardiac computed tomography.

METHODS

We evaluated 477 patients with acquired aortic valve disease by cardiac computed tomography to assess variability in cardiac structures established to relate to the conduction system. We standardized 3 points (points A-C) to estimate the course from the atrioventricular node to the nonbranching bundle and left bundle branch origin and further compared this with measures of variability in the aortic root and membranous septum.

RESULTS

The mean distances between the aortic valve virtual basal ring and points A, B, and C were 9.5 ± 3.5 (0.3-20.1) mm, 5.0 ± 2.6 (-1.7 to 15.9) mm, and 2.9 ± 2.5 (-5.2 to 12.0) mm, respectively. The midpoint of the membranous septum deviated posteriorly a median of -4.4 (interquartile range, -12.4 to +3.0) degrees relative to the commissure between the right coronary and noncoronary leaflets. Intraclass coefficients for both intraobserver and interobserver variability for all measured points were excellent (≥0.78).

CONCLUSION

These findings further infer the intimate yet highly variable relationship between the conduction axis and aortic root. This reproducible and standardized approach needs validation in populations of patients requiring accurate identification of the atrioventricular components of the conduction axis, which may serve as a noninvasive means for estimating its location.

Stylet-driven leads versus lumenless pacing leads in patients with left bundle branch area pacing: A systematic review and meta-analysis

BACKGROUND

Despite advancements in lead designs for optimum left bundle branch area pacing (LBBAP), limited data exist on the performance of stylet-driven leads (SDLs).

OBJECTIVE

This meta-analysis sought to compare the performance and safety of SDLs in comparison with lumenless leads (LLLs) following LBBAP.

METHODS

Systematic literature search was conducted using PubMed, Europe PMC, and ScienceDirect for studies that compared the outcomes of SDLs during LBBAP compared with LLLs. Study outcomes included periprocedural parameters, pacing metrics, and complications.

RESULTS

A total of 6 studies involving 3991 participants were included. LBBAP procedural success was comparable between SDLs and LLLs (90.2% and 90.5%, respectively). Compared with LLLs, SDLs appeared to result in shortened procedural (-11.50 minutes) and fluoroscopy (-2.56 minutes) times, along with increased capture threshold and reduced lead impedance at implantation. However, paced QRS, R-wave amplitude, capture threshold, and lead impedance remained comparable between both groups during follow-up. The number of lead-implantation attempts was similar between SDLs and LLLs (2.6 ± 1.0 vs 2.2 ± 0.6). Lead dislodgement and lead-related complications (except septal perforation) occurred mostly in the SDL group. No statistical differences were found in life-threatening complications.

CONCLUSION

SDLs demonstrated comparable effectiveness in achieving LBBAP, exhibiting similar success rates, mean attempts for lead placement, and pacing parameters, although they were associated with a higher overall incidence of lead-related complications. The reduced overall procedural and fluoroscopy time may be attributed to the ability of SDLs' different delivery sheath selections in identifying the optimal anatomical site, rather than being lead specific.

Intraprocedural transthoracic EChocardiography to facilitate Left Bundle Branch Pacing: EC-LBBP

BACKGROUND

Left bundle branch (LBB) pacing (LBBP) has gained rapid adoption. Evidence for direct LBB capture has varied from 30%-95% depending on the criteria.

OBJECTIVE

The purpose of this study was to assess the feasibility and efficacy of intraprocedural transthoracic echocardiographic guidance to achieve LBB capture.

METHODS

This was a prospective, nonrandomized, case-control study (ClinicalTrials.gov Identifier: NCT05646251). The pectoral region including echocardiographic windows were sterile-draped using Ioban. The lead was placed in the right ventricular septum and sheath orientation adjusted under echocardiography. The lead was advanced under echocardiographic visualization until the tip reached the left ventricular subendocardium. LBB capture was strictly defined: transition from nonselective to selective/left ventricular septal capture; LBB potential with injury current; and Delta (HBP-LBBP) V6RWPT ≥10.

RESULTS

Thirty patients underwent echocardiography-guided left bundle branch pacing (EC-LBBP) and compared with 30 patients (standard approach): mean age 74.4 ± 10 years; female 45%; hypertension 92%; cardiomyopathy 43%; atrioventricular block/atrioventricular nodal ablation 75%. Total procedural and fluoroscopy durations were similar. Left bundle branch area pacing (LBBAP or left ventricular septal pacing) was successful in all patients in both groups. EC-LBBP was 97% successful in achieving LBB capture vs 70% (P = .02) with LBB potentials (LB-V 23 ± 6 ms) in 95% vs 77% (22 ± 6 ms). Morphology transition confirming LBB capture was seen in 87% vs 67% (P = .02). Lead tip was visualized at the left ventricular subendocardium in 100% of patients in EC-LBBP.

CONCLUSION

EC-LBBP was 97% successful in achieving LBB capture using strict criteria. LBBP lead was subendocardial in all patients. EC-LBBP is practical, feasible, safe, and highly effective in achieving LBB capture.

Optimizing outcomes from cardiac resynchronization therapy: what do recent data and insights say?

INTRODUCTION

Cardiac Resynchronization Therapy (CRT) is an effective treatment for heart failure (HF) in approximately two-thirds of recipients, with a third remaining CRT 'non-responders.' There is an increasing body of evidence exploring the reasons behind non-response, as well as ways to preempt or counteract it.

AREAS COVERED

This review will examine the most recent evidence regarding optimizing outcomes from CRT, as well as explore whether traditional CRT indeed remains the best first-line therapy for electrical resynchronization in HF. We will start by discussing methods of preempting non-response, such as refining patient selection and procedural technique, before reviewing how responses can be optimized post-implantation. For the purpose of this review, evidence was gathered from electronic literature searches (via PubMed and GoogleScholar), with a particular focus on primary evidence published in the last 5 years.

EXPERT OPINION

Ever-expanding research in the field of device therapy has armed physicians with more tools than ever to treat dyssynchronous HF. Newer developments, such as artificial intelligence (AI) guided device programming and conduction system pacing (CSP) are particularly exciting, and we will discuss how they could eventually lead to truly personalized care by maximizing outcomes from CRT.

Transvenous extraction of conduction system and lumenless pacing leads

INTRODUCTION

Conduction system pacing (CSP), often accomplished with lumenless pacing leads, is increasingly employed to achieve physiologic ventricular activation. There are limited data on the extraction of these leads. The objective of this study was to describe the safety and efficacy of extraction of CSP pacing leads and compare outcomes with extraction of non-CSP lumenless leads.

METHODS

Patients undergoing CSP/non-CSP lumenless lead removal were included. Outcomes of interest included rates of complete procedural success, complications, and successful reimplantation.

RESULTS

Overall, 23 patients were included (n = 14 with CSP and n = 9 with non-CSP lumenless leads implanted in the right atrium, right ventricle, or septum). The mean age was 52.7 ± 24.0 years, 30% were female, and the mean lead age was 4.5 ± 4.4 years. The complete procedural success rate was 100%. One serious complication occurred in the non-CSP group but was unrelated to the lead of interest. Manual traction alone was successful in 57% of CSP cases (mean lead age 2.4 ± 1.7 years) and in 11% of non-CSP cases (mean lead age 7.9 ± 5.3 years). Laser sheaths were used in 43% of CSP cases and 89% of non-CSP cases; rotational cutting tools were used in no CSP cases and in 33% of non-CSP cases. Reimplantation in the conduction system was attempted with a left bundle branch pacing lead and successful in 80% (n = 4/5).

CONCLUSION

Extraction of CSP and non-CSP lumenless leads is feasible with a high success rate and a good safety profile. CSP reimplantation after extraction is also feasible with good electrical performance.

A new dimension in cardiac imaging: Three-dimensional exploration of the atrioventricular conduction axis with hierarchical phase-contrast tomography

Much of our understanding of the atrioventricular conduction axis has been derived from early 20th-century histologic investigations. These studies, although foundational, are constrained by their 2-dimensional representation of complex 3-dimensional anatomy. The variability in the course of the atrioventricular conduction axis, and its relationship to surrounding cardiac structures, necessitates a more advanced imaging approach. Using hierarchical phase-contrast tomography of an autopsied heart specimen with cellular resolution, this review provides a contemporary understanding of the atrioventricular conduction axis. By correlating these findings with 3-dimensional computed tomographic reconstructions in living patients, we offer clinicians the insights needed accurately to predict the location of the atrioventricular conduction axis. This novel approach overcomes the inherent limitations of 2-dimensional histology, enhancing our ability to understand and visualize the intricate relationships of the conduction axis within the heart.

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.

New-Onset Left Ventricular Dysfunction After Left Bundle Branch Pacing

BACKGROUND

Left bundle branch pacing (LBBP) provides stable pacing parameters and has been suggested as an alternative for right ventricular pacing and cardiac resynchronization therapy.

OBJECTIVES

The aim of the study was to assess the incidence and etiology of new-onset left ventricular dysfunction (NOLVD) following LBBP in patients with baseline normal left ventricular (LV) function and cardiomyopathy patients with normalized LV function.

METHODS

Patients undergoing successful LBBP for symptomatic bradyarrhythmia or as an alternative to cardiac resynchronization therapy were included. Normalization of LV function was defined as improvement in LV ejection fraction to ≥50%. Patients with baseline normal LV function and those with recovered LV function after LBBP constituted the study group. Loss of conduction system capture (LOCSC) was defined as complete or partial loss of right bundle branch delay pattern along with inability to demonstrate capture transition during threshold assessment.

RESULTS

A total of 426 patients were included; 59% (n = 250) had baseline normal LV function (group I) and 41% (n = 176) had recovered LV function after LBBP (group II). Mean follow-up duration of 28.3 ± 16.7 months. NOLVD was noted in 3.75% (n = 16; group I, n = 5, and group II, n = 11) of patients. The etiologies for NOLVD were LOCSC in 62.5% (n = 10), suboptimal atrioventricular (AV) delay in 18.7% (n = 3), atrial fibrillation in 6.3% (n = 1), and idiopathic in 12.5% (n = 2). LOCSC occurred at a mean interval of 9.2 ± 6.4 months after the initial implantation. Reinterventions (n = 6) including lead repositioning, AV delay optimization, and AV junction ablation resulted in renormalization of LV function in all 6 patients.

CONCLUSIONS

Periodic assessment in device clinic is required because NOLVD from reversible causes can occur during follow-up in patients after LBBP.

A meta-analysis of the distance between lead-implanted site and tricuspid valve annulus with postoperative tricuspid regurgitation deterioration in patients with left bundle branch area pacing

Tricuspid regurgitation (TR) is a known complication of cardiac implantable electrical devices (CIEDs), with prevalences ranging from 10% to as high as 30%. Despite left bundle branch area pacing (LBBAP) has emerged as an alternative to the limits of His-bundle pacing (HBP), the long-term safety of this procedure, notably the worsening of TR after implantation, has yet to be thoroughly investigated. This meta-analysis sought to determine the frequency of post-LBBAP TR deterioration and identify the predictors, particularly the distance between lead-implanted site and the tricuspid valve annulus (lead-TA-distance). A systematic literature search was conducted using PubMed, Europe PMC, and ScienceDirect for studies that reported the incidence of deterioration and measurement of TR grade at baseline and follow-up following LBBAP, in addition to the differences in exposure between short and long lead-TA-distances. A total of three studies involving 480 participants were included in this meta-analysis. The incidence of TR deterioration was 22%. Patients with TR deterioration also demonstrated a significantly shorter lead-TA-distance in comparison to the opposing group (MD: -5.74 mm (-0.70, -10.78); p < .001; I2 = 92.6%). The pooled results of three comparative studies suggest that participants in the longer lead-TA-distance group had a significant decrement in the likelihood of TR worsening (adjusted OR = 0.59 (0.36-0.96); p = .034; I2 = 79%). Multivariate analysis conducted in each of the included investigations supported the independence of the connection between lead-TA-distance and TR deterioration. A shorter lead-TA-distance was an independent risk factor for TR deterioration in individuals with post-LBBAP implantation.

Percutaneous balloon venoplasty for symptomatic lead-related venous stenosis

BACKGROUND

Lead-related venous stenosis (LRVS) is common after transvenous lead implantation and generally diagnosed incidentally. Symptomatic LRVS, causing discomfort and swelling, is less common.

OBJECTIVE

We report on the management and outcomes of patients with symptomatic LRVS after percutaneous balloon venoplasty.

METHODS

We included patients with symptomatic LRVS unresponsive to >30 days of anticoagulation who underwent venoplasty at the Hospital of the University of Pennsylvania between 2014 and 2020. Transvenous lead extraction (TLE) was performed first if the lesion could not be crossed with a wire.

RESULTS

Eighteen patients (mean age, 62 ± 10 years; 44% female) underwent 27 venoplasty procedures. Symptoms included arm swelling in 9 (50%), facial/neck swelling in 1 (6%), and both in 8 (44%). Venography revealed LRVS in the axillary/subclavian veins in 10 (56%), the brachiocephalic vein in 6 (33%), and the superior vena cava in 4 (11%). Most patients (83%) required TLE before venoplasty, and only 5 of 18 (28%) remained with leads crossing the stenosed segment. Thirteen patients (72%) had complete symptom resolution, 4 (22%) had partial resolution due to secondary lymphedema, and 1 showed no improvement. Patients with complete resolution had shorter times from symptom onset to intervention (195 vs 690 days; P = .02).

CONCLUSION

LRVS can affect any part of the venous system and may be manifested with swelling of the arm, face/neck, or both. Balloon venoplasty is safe and effective, often requires TLE, and is particularly durable when leads no longer cross the stenosed region. Venoplasty is less effective for secondary lymphedema, highlighting the need for timely intervention.

Safety, efficacy, and reliability evaluation ofa novel small-diameter defibrillation lead: Global LEADR pivotal trial results

BACKGROUND

Implantable cardioverter-defibrillators last longer, and interest in reliable leads with targeted lead placement is growing. The OmniaSecure defibrillation lead is a novel, small-diameter, catheter-delivered lead designed for targeted placement, based on the established SelectSecure SureScan MRI Model 3830 lumenless pacing lead platform.

OBJECTIVE

This trial assessed safety and efficacy of the OmniaSecure defibrillation lead.

METHODS

The worldwide LEADR pivotal clinical trial enrolled patients indicated for de novo implantation of a primary or secondary prevention implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator, all of whom received the study lead. The primary efficacy end point was successful defibrillation at implantation per protocol. The primary safety end point was freedom from study lead-related major complications at 6 months. The primary efficacy and safety objectives were met if the lower bound of the 2-sided 95% credible interval was >88% and >90%, respectively.

RESULTS

In total, 643 patients successfully received the study lead, and 505 patients have completed 12-month follow-up. The lead was placed in the desired right ventricular location in 99.5% of patients. Defibrillation testing at implantation was completed in 119 patients, with success in 97.5%. The Kaplan-Meier estimated freedom from study lead-related major complications was 97.1% at 6 and 12 months. The trial exceeded the primary efficacy and safety objective thresholds. There were zero study lead fractures and electrical performance was stable throughout the mean follow-up of 12.7 ± 4.8 months (mean ± SD).

CONCLUSION

The OmniaSecure lead exceeded prespecified primary end point performance goals for safety and efficacy, demonstrating high defibrillation success and a low occurrence of lead-related major complications with zero lead fractures.

Improved all-cause mortality with left bundle branch area pacing compared to biventricular pacing in cardiac resynchronization therapy: a meta-analysis

BACKGROUND

Left bundle branch area pacing (LBBAP) has emerged as a physiological alternative pacing strategy to biventricular pacing (BIVP) in cardiac resynchronization therapy (CRT). We aimed to assess the impact of LBBAP vs. BIVP on all-cause mortality and heart failure (HF)-related hospitalization in patients undergoing CRT.

METHODS

Studies comparing LBBAP and BIVP for CRT in patients with HF with reduced left ventricular ejection fraction (LVEF) were included. The coprimary outcomes were all-cause mortality and HF-related hospitalization. Secondary outcomes included procedural and fluoroscopy time, change in QRS duration, and change in LVEF.

RESULTS

Thirteen studies (12 observational and 1 RCT, n = 3239; LBBAP = 1338 and BIVP = 1901) with a mean follow-up duration of 25.8 months were included. Compared to BIVP, LBBAP was associated with a significant absolute risk reduction of 3.2% in all-cause mortality (9.3% vs 12.5%, RR 0.7, 95% CI 0.57-0.86, p < 0.001) and an 8.2% reduction in HF-related hospitalization (11.3% vs 19.5%, RR 0.6, 95% CI 0.5-0.71, p < 0.00001). LBBAP also resulted in reductions in procedural time (mean weighted difference- 23.2 min, 95% CI - 42.9 to - 3.6, p = 0.02) and fluoroscopy time (- 8.6 min, 95% CI - 12.5 to - 4.7, p < 0.001) as well as a significant reduction in QRS duration (mean weighted difference:- 25.3 ms, 95% CI - 30.9 to - 19.8, p < 0.00001) and a greater improvement in LVEF of 5.1% (95% CI 4.4-5.8, p < 0.001) compared to BIVP in the studies that reported these outcomes.

CONCLUSION

In this meta-analysis, LBBAP was associated with a significant reduction in all-cause mortality as well as HF-related hospitalization when compared to BIVP. Additional data from large RCTs is warranted to corroborate these promising findings.

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.

Feasibility of Single-lead Cardiac Resynchronization and Defibrillation Therapy in an Animal Model

Conduction system pacing (CSP) has emerged as an alternative to cardiac resynchronization therapy (CRT); however, there is limited experience with CSP using implantable cardiac defibrillator (ICD) leads. The achievement of CSP with an ICD lead may yield comparable results to cardiac resynchronization therapy defibrillator (CRT-D) therapy using fewer leads. We implanted the Biotronik Linox DX "VDD"-programmable ICD lead in a swine model to investigate the feasibility of "single-lead" CRT-D implantation. With the lead embedded in the basal right ventricular septum, morphologic criteria for CSP were achieved, and successful defibrillation was performed while maintaining atrial sensing. Future work may assure reproducibility of these findings and further determine the feasibility of a single-lead CRT-D.

Efficacy of left bundle branch area pacing versus biventricular pacing in patients treated with cardiac resynchronization therapy: Select site - cohort study

BACKGROUND

Cardiac resynchronization therapy (CRT) is typically attempted with biventricular (BiV) pacing. One-third of patients are nonresponders. Left bundle branch area pacing (LBBAP) has been evaluated as an alternative means.

OBJECTIVE

The purpose of this study was to assess the feasibility and clinical response of permanent LBBAP as an alternative to BiV pacing.

METHODS

Of 479 consecutive patients referred with heart failure, 50 with BiV-CRT and 51 with LBBAP-CRT were included in this analysis after study exclusions. Quality-of-Life (QoL) assessments, echocardiographic measurements, and New York Heart Association (NYHA) class were obtained at baseline and at 6-monthly intervals.

RESULTS

There were no differences in baseline characteristics between groups (all P > .05). Clinical outcomes such as left ventricular ejection fraction, left ventricular end-systolic volume, QoL, and NYHA class were significantly improved for both pacing groups compared to baseline. The LBBAP-CRT group showed greater improvement in left ventricular ejection fraction at 6 months (P = .001) and 12 months (P = .021), accompanied by greater reduction in left ventricular end-systolic volume (P = .007). QRS duration < 120 ms (baseline 160.82 ± 21.35 ms vs 161.08 ± 24.48 ms) was achieved in 30% in the BiV-CRT group vs 71% in the LBBAP-CRT group (P ≤ .001). Improvement in NYHA class (P = .031) and QoL index was greater (P = .014). Reduced heart failure admissions (P = .003) and health care utilization (P < .05) and improved lead performance (P < .001) were observed in the LBBAP-CRT group.

CONCLUSION

LBBAP-CRT is feasible and effective CRT. It results into a meaningful improvement in QoL and reduction in health care utilization. This can be offered as an alternative to BiV-CRT or potentially as first-line therapy.

Conduction system pacing versus biventricular pacing in heart failure with reduced ejection fraction: A systematic review and meta-analysis of randomized controlled trials

Conduction system pacing (CSP) has emerged as a promising alternative to biventricular pacing (BVP) in patients with heart failure with reduced ejection fraction (HFrEF) and ventricular dyssynchrony, but its benefits are uncertain. In this study, we aimed to evaluate clinical outcomes of CSP vs BVP for cardiac resynchronization in patients with HFrEF. PubMed, Scopus, and Cochrane databases were searched for randomized controlled trials comparing CSP to BVP for resynchronization therapy in patients with HFrEF. Heterogeneity was examined with I2 statistics. A random-effects model was used for all outcomes. We included 7 randomized controlled trials with 408 patients, of whom 200 (49%) underwent CSP. Compared to BVP, CSP resulted in a significantly greater reduction in QRS duration (MD -13.34 ms; 95% confidence interval [CI] -24.32 to -2.36, P = .02; I2 = 91%) and New York Heart Association functional class (standardized mean difference [SMD] -0.37; 95% CI -0.69 to -0.05; P = .02; I2 = 41%), and a significant increase in left ventricular ejection fraction (mean difference [MD] 2.06%; 95% CI 0.16 to 3.97; P = .03; I2 = 0%). No statistical difference was noted for left ventricular end-systolic volume (SMD -0.51 mL; 95% CI -1.26 to 0.24; P = .18; I2 = 83%), lead capture threshold (MD -0.08 V; 95% CI -0.42 to 0.27; P = .66; I2 = 66%), and procedure time (MD 5.99 minutes; 95% CI -15.91 to 27.89; P = .59; I2 = 79%). These findings suggest that CSP may have electrocardiographic, echocardiographic, and symptomatic benefits over BVP for patients with HFrEF requiring cardiac resynchronization.

Conduction System Stimulation to Avoid Left Ventricle Dysfunction

BACKGROUND

Right ventricular apical pacing (RVAP) can produce left ventricle dysfunction. Conduction system pacing (CSP) has been used successfully to reverse left ventricle dysfunction in patients with left bundle branch block. To date, data about CSP prevention of left ventricle dysfunction in patients with preserved left ventricular ejection fraction (LVEF) are scarce and limited mostly to nonrandomized studies. Our aim is to demonstrate that CSP can preserve normal ventricular function compared with RVAP in the setting of a high burden of ventricular pacing.

METHODS

Consecutive patients with a high-degree atrioventricular block and preserved or mildly deteriorated LVEF (>40%) were included in this prospective, randomized, parallel, controlled study, comparing conventional RVAP versus CSP.

RESULTS

Seventy-five patients were randomized, with no differences between basal characteristics in both groups. The stimulated QRS duration was significantly longer in the RVAP group compared with the CSP group (160.4±18.1 versus 124.2±20.2 ms; p<0.01). Seventy patients were included in the intention-to-treat analyses. LVEF showed a significant decrease in the RVAP group at 6 months compared with the CSP group (mean difference, -5.8% [95% CI, -9.6% to -2%]; P<0.01). Left ventricular end-diastolic diameter showed an increase in the RVAP group compared with the CSP group (mean difference, 3.2 [95% CI, 0.1-6.2] mm; P=0.04). Heart failure-related admissions were higher in the RVAP group (22.6% versus 5.1%; P=0.03).

CONCLUSIONS

Conduction system stimulation prevents LVEF deterioration and heart failure-related admissions in patients with normal or mildly deteriorated LVEF requiring a high burden of ventricular pacing. These results are only short term and need to be confirmed by further larger studies.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT06026683.

Arrhythmic Risk in Biventricular Pacing Compared With Left Bundle Branch Area Pacing: Results From the I-CLAS Study

BACKGROUND

Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP.

METHODS

The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score-matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model.

RESULTS

Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score-matched patients (propensity score-matched BVP, 707; propensity score-matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29-0.74]; P<0.001). The incidence of VT storm (>3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P=0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P<0.001). In 1194 patients with no history of VT/VF or antiarrhythmic therapy (BVP, 591; LBBAP, 603), the occurrence of VT/VF was significantly lower with LBBAP than with BVP (3.2% versus 7.3%; hazard ratio, 0.46 [95% CI, 0.26-0.81]; P=0.007). Among patients with no history of AF (n=890), the occurrence of new-onset AF >30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16-0.73]; P=0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P=0.015).

CONCLUSIONS

LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP.

Conventional biventricular pacing is still preferred to conduction system pacing for atrioventricular block in patients with reduced ejection fraction and narrow QRS

It is well established that right ventricular pacing is detrimental in patients with reduced cardiac function who require ventricular pacing (VP), and alternatives nowadays are comprised of biventricular pacing (BiVP) and conduction system pacing (CSP). The latter modality is of particular interest in patients with a narrow baseline QRS as it completely avoids, or minimizes, ventricular desynchronization associated with VP. In this article, experts debate whether BiVP or CSP should be used to treat these patients.

Acute performance of stylet driven leads for left bundle branch area pacing: A comparison with lumenless leads

Background

Lumenless leads (LLLs) are widely used for left bundle branch area pacing (LBBAP). Recently, stylet-driven leads (SDLs) have also been used for LBBAP.

Objective

The purpose of this study was to evaluate the acute performance of SDLs during LBBAP in comparison with LLLs.

Methods

Consecutive patients undergoing LBBAP for bradycardia or cardiac resynchronization therapy indications at 2 high-volume, early conduction system pacing adopters, tertiary centers were included from January 2019 to July 2023. Patients received either SDLs or LLLs at the discretion of the implanting physician. Acute performance and follow-up data of both lead types were evaluated.

Results

A total of 925 LBBAP implants were included, 655 using LLLs and 270 using SDLs. Overall, LBBAP acute success was significantly higher with LLLs than SDLs (95.3% vs 85.1%, respectively; P <.001) even after the learning curve (97% vs 86%; P = .013). LLLs were implanted in more mid-basal septal positions in comparison with SDLs, which tended to be implanted in more inferior and mid-apical septal positions. Acute lead-related complications were higher with SDLs than LLLs (15.9% vs 6.1%, respectively; P <.001) with 15 cases of lead damage during implant (4.4% vs 0.5%; P <.001) but decreased with acquired experience and were comparable in the last 100 patients included in each group. Lead implant and fluoroscopy times were shorter for SDLs, with lead dislodgment occurring in 0.9% with LLLs and 1.5% with SDLs (P = .489).

Conclusion

Acute lead performance proved to be different between LLLs and SDLs. A specific learning curve should be considered for SDLs even for implanters with extensive previous experience with LLLs.