Meta-Analysis Comparing Safety and Efficacy of Left Bundle Branch Area Pacing Versus His Bundle Pacing

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.

Disorders of cardiac rhythm in China

The Annual Report on Cardiovascular Health and Diseases in China (2022) intricate landscape of cardiovascular health in China. In connection with the previous section, this seventh section of the report offers a comprehensive analysis of disorders of heart rhythm in China. In 2021, China has achieved significant development and gratifying results in many aspects of the field of arrhythmia. Left bundle branch pacing (LBBP), as an emerging pacing technique originating from China, has received widespread attention. New research results have emerged on its indications, surgical procedures, clinical evaluation, and comparison with other pacing techniques. Its feasibility, effectiveness, and safety have been basically verified, but its long-term prognosis still needs further confirmation from larger samples and longer follow-up time research results. Leadless pacemakers have begun to be used in a wider range of clinical applications, and related large sample cohort studies have been reported. In addition, there are also noteworthy new achievements in the fields of pacemaker remote programming, anticoagulation and radiofrequency catheter ablation (RFCA) therapy for atrial fibrillation, and implantable cardioverter defibrillator prevention of sudden cardiac death. In terms of clinical practice, due to COVID-19 pandemic, the number of RFCA procedures and other device implantations in China has fluctuated, but it has gradually recovered since 2020.

Success and complication rates of conduction system pacing: a meta-analytical observational comparison of left bundle branch area pacing and His bundle pacing

BACKGROUND

Left bundle branch area pacing (LBBAP) and His bundle pacing (HBP) are the main strategies to achieve conduction system pacing (CSP), but only observational studies with few patients have compared the two pacing strategies, sometimes with unclear results given the different definitions of the feasibility and safety outcomes. Therefore, we conducted a meta-analysis aiming to compare the success and complications of LBBAP versus HBP.

METHODS

We systematically searched the electronic databases for studies published from inception to March 22, 2023, and focusing on LBBAP versus HBP. The study endpoints were CSP success rate, device-related complications, CSP lead-related complications and non-CSP lead-related complications.

RESULTS

Fifteen observational studies enrolling 2491 patients met the inclusion criteria. LBBAP led to a significant increase in procedural success [91.1% vs 80.9%; RR: 1.15 (95% CI: 1.08-1.22); p < 0.00001] with a significantly lower complication rate [1.8% vs 5.2%; RR: 0.48 (95% CI: 0.29-0.78); p = 0.003], lead-related complications [1.1% vs 4.3%; RR: 0.38 (95% CI: 0.21-0.72); p = 0.003] and lead failure/deactivation [0.2% vs 3.9%; RR: 0.16 (95% CI: 0.07-0.35); p < 0.00001] than HBP. No significant differences were found between CSP lead dislodgement and non-CSP lead-related complications.

CONCLUSION

This meta-analysis of observational studies showed a higher success rate of LBBAP compared to HBP with a lower incidence of complications.

Assessing Torque Transfer in Conduction System Pacing: Development and Evaluation of an Ex Vivo Model

BACKGROUND

Conduction system pacing (CSP) faces challenges in achieving reliable and safe deployments. Complex interactions between tissue and lead tip can result in endocardial entanglement, a drill effect that prevents penetration. No verified ex vivo model exists to quantitatively assess this relationship.

OBJECTIVES

The purpose of this study was to quantitatively characterize CSP lead tip to tissue responses for 4 commonly used leads.

METHODS

CSP leads (from Medtronic, Biotronik, Boston Scientific, and Abbott) were examined for helix rotation efficiency in ex vivo ovine right ventricular septa. A custom jig was utilized for rotation measurements. Fifteen turns were executed, documenting tissue-interface changes every 90° using high-resolution photography. Response curves (input rotation vs helix rotation) were evaluated using piecewise linear regression, with a focus on output vs input response slopes and torque breakpoint events.

RESULTS

We analyzed 3,840 quarter-turn CSP insertions with 4 different lead types. Helix rotations were consistently less than input: Abbott Tendril = 0.21:1, Medtronic 3830 = 0.21:1, Biotronik Solia = 0.47:1, and Boston Scientific Ingevity = 0.56:1. Torque breakpoint events were observed on average 7.22 times per insertion (95% CI: 6.08-8.35; P = NS) across all leads. In 57.8% of insertions (37 of 64), uncontrolled torque breakpoint events occurred, signaling unexpected excess helix rotations.

CONCLUSIONS

Using a robust ex vivo model, we revealed a muted helix rotation response compared with input turns on the lead, and frequent torque change events during insertion. This is critical for CSP implanters, emphasizing the potential for unexpected torque breakpoint events, and suggesting the need for novel lead designs or deployment methods to enhance CSP efficiency and safety.

Utility of a guiding catheter for conduction system pacing: An early multicenter experience

Background

Conduction system pacing (CSP), either as His bundle pacing (HBP) or as left bundle branch area pacing (LBBAP), may be superior to right ventricular apical or septal pacing.

Objective

The study sought to present acute results for a new guiding catheter (Biotronik Selectra 3D) designed for CSP implantations of a retractable screw-in lead (Biotronik Solia S).

Methods

The primary endpoint of the prospective, international nonrandomized BIO|MASTER.Selectra 3D study was freedom from catheter-related serious adverse device effects (SADEs) within 1 week of lead implantation.

Results

Of 157 enrolled patients, CSP was achieved in 147 (93.6%) patients. No SADEs occurred within 7 days. LBBAP was achieved in 82 patients (45 as crossover from an HBP attempt) and HBP in 65 (44.2%) patients. In centers considering both HBP and LBBAP, the CSP implantation success approached 99%. Successful CSP implantations lasted on average ∼50 minutes (fluoroscopy ∼6 minutes). Most procedures (87.9%) needed only 1 catheter, even after switch from HBP to LBBAP. The catheter's handling was rated largely positive. In patients without bundle branch block, mean QRS duration increased from 106 ms (intrinsic) to 122 ms (CSP) (P = .001). In patients with bundle branch block, mean QRS duration decreased from 151 ms (intrinsic) to 137 ms (CSP) (P = .004).

Conclusion

The Selectra 3D catheter is a valuable tool for HBP and LBBAP implantations of the stylet-supported pacemaker leads. When implanters considered both HBP and LBBAP, the success rate was ∼99%. Flexibility to change between different approaches may be advisable in heterogeneous and challenging areas, such as CSP implantations.

Improved Outcomes of Conduction System Pacing in Heart Failure with Reduced Ejection Fraction - A Systematic Review and Meta-analysis

Conduction system pacing (CSP) - His bundle pacing (HBP) and Left bundle branch area pacing (LBBAP) - are emerging alternatives to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) in heart failure. However, evidence is largely limited to small and observational studies. We conducted a meta-analysis including a total of 15 randomized control trials (RCTs) and non-RCTs that compare CSP (HBP & LBBAP) with BVP in patients with CRT indications. We assessed the mean differences in QRS duration (QRSd), pacing threshold, left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class score. CSP resulted in a pooled mean QRSd improvement of -20.3 ms (95% CI -26.1 - -14.5, p<0.05, I²=87.1%) versus BVP. For LVEF, a weighted mean increase of 5.2% (95% CI 3.5-6.9, p<0.05, I²=55.6) was observed following CSP versus BVP. The mean NYHA score was reduced by -0.40 (95% CI -0.6 - -0.2, p<0.05, I²=61.7) post-CSP versus BVP. Subgroup analysis of outcomes by LBBAP and HBP demonstrated statistically significant weighted mean improvements from both CSP modalities for QRSd and LVEF compared to BVP. LBBAP resulted in NYHA improvement compared to BVP without differences between CSP subgroups. LBBAP is associated with a significantly lowered mean pacing threshold of -0.51V (95% CI -0.68 - -0.38) whilst HBP had increased the mean threshold (0.62V, 95% CI -0.03 - 1.26) compared to BVP, however, this was associated with significant heterogeneity. Overall, both CSP techniques are feasible and effective CRT alternatives for heart failure. Further RCTs are needed to establish long-term efficacy and safety.

Biventricular endocardial pacing and left bundle branch area pacing for cardiac resynchronization: Mechanistic insights from electrocardiographic imaging, acute hemodynamic response, and magnetic resonance imaging

BACKGROUND

Biventricular endocardial pacing (BiV-endo) has demonstrated superior cardiac resynchronization compared to conventional biventricular epicardial pacing (BiV-epi). Left bundle branch area pacing (LBBAP) may also achieve effective cardiac resynchronization therapy (CRT).

OBJECTIVE

The purpose of this study was to compare the acute electrical and hemodynamic effects of BiV-epi, BiV-endo, and LBBAP delivered from the LV endocardium and to assess how myocardial scar affects response.

METHODS

Eleven patients with heart failure and indications for CRT underwent a temporary pacing study with electrocardiographic imaging (ECGi) and hemodynamic assessment. BiV-endo was delivered by stimulation of the left ventricular (LV) lateral wall, and LBBAP was delivered by stimulation of the LV septum, at the site of a Purkinje potential. LV activation time (LVAT-95), LV dyssynchrony index (LVDI), biventricular activation time (BIVAT-90), and biventricular dyssynchrony index (BIVDI) were calculated. Myocardial scar was assessed using magnetic resonance imaging (MRI).

RESULTS

The protocol was completed in 10 patients. Compared to BiV-epi (LVAT-95: 79.2 ± 13.1 ms; LVDI: 26.6 ± 3.4 ms) LV resynchronization was superior during BiV-endo (LVAT-95: 48.5 ± 14.9 ms; P = .001; LVDI: 16.6 ± 6.4 ms; P = .002) and LBBAP (LVAT-95: 48.9 ± 12.5 ms; P = .001; LVDI: 15.3 ± 3.4 ms; P = .001). Biventricular resynchronization was similarly superior during BiV-endo and LBBAP vs BiV-epi (BIVAT-90 and BIVDI; P <.05). The rate of acute hemodynamic responders was higher during BiV-endo (90%) and LBBAP (70%) vs BiV-epi (50%). The benefits of LBBAP (but not BiV-endo) on LV resynchronization were attenuated when septal scar was present in a subset of 8 patients who underwent MRI.

CONCLUSION

Our findings suggest superior electrical resynchronization and a higher proportion of acute hemodynamic responders during BiV-endo and LBBAP compared to BiV-epi. Electrical resynchronization was similar between BiV-endo and LBBAP; however, septal scar seemed to attenuate response to LBBAP.

Assessment of Cardiac Function and Ventricular Mechanical Synchronization in Left Bundle Branch Area Pacing by Speckle Tracking and Three-Dimensional Echocardiography

Real-time 3-dimensional echocardiography combined with speckle tracking was used in this study. A total of 90 patients with normal left ventricular ejection fraction were divided into 3 groups according to the pacing site: left bundle branch area pacing (LBBAP), right ventricular septal pacing (RVSP) or right ventricular apical pacing (RVAP). Procedure duration (90 ± 18 vs 61 ± 6.6 vs 58 ± 5.6 minutes, p = 0.015), Fluoroscopy duration (15.5 ± 5.4 vs 4.8 ± 2.2 vs 4 ± 1.9 minutes, p = 0.004), and ventricular capture threshold at implantation (0.8 ± 0.3 vs 0.6 ± 0.2 vs 0.6 ± 0.1 V, p = 0.002) were significantly increased in patients that received LBBAP compared with RVSP or RVAP. At 4 weeks of follow-up, brain natriuretic peptide levels were significantly lower (22 [12 to 59] vs 135 [86 to 231] vs 235 [147 to 428] pg/ml, p = 0.04), paced QRS duration was significantly shorter (115 ± 26 vs 134 ± 28 vs 157 ± 29 ms, p = 0.012), and global longitudinal strain (-19.4 ± 2.4 vs -19.3 ± 3.4 vs -17.3 ± 3.5%, p = 0.026) and systolic dyssynchrony index (2.5 ± 0.3 vs 5.9 ± 0.9 vs 7.7 ± 1.2, p = 0.001), longitudinal absolute maximum difference of time to peak strain (17 [6 to 68] vs 117 [71 to 173] vs 126 [79 to 178] ms, p <0.0001), and circumferential absolute maximum difference of time to peak strain (76 [32 to 129] vs 148 [117 to 208] vs 161 [118 to 266] ms, p = 0.005) were significantly lower in patients that received LBBAP compared with RVSP or RVAP. In conclusion, LBBAP can provide a more physiological ventricular activation pattern than RVSP or RVAP and results in good left ventricular electrical and mechanical synchronization.

Conduction system pacing learning curve: Left bundle pacing compared to His bundle pacing

Introduction

Conduction system pacing (CSP), consisting of His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) is a rapidly developing field. These pacing techniques result in single lead left ventricular resynchronisation. Understanding of the associated learning curve of the two techniques is an important consideration for new implanters/implanting centres.

Methods

We conducted a review of the first 30 cases of both HBP and LBBAP at The Royal Brompton Hospital. The procedural duration and fluoroscopy time were used as surrogates for the learning curve of each technique.

Results

Patient characteristics were similar in HBP and LBBAP groups; LV ejection fraction (46% vs 54%, p = 0.08), pre-procedural QRS duration (119 ms vs 128 ms, p = 0.32).Mean procedural duration was shorter for LBBAP than for HBP (87 vs 107mins, p = 0.04) and the drop in procedural duration was more marked in LBBAP, plateauing and remaining low at 80mins after the initial 10 cases. Fluoroscopic screening time mirrored procedural duration (8 min vs 16 min, p < 0.01).

Discussion/Conclusion

Our data suggest that the CSP learning curve was shorter for LBBAP than for HBP and appears to plateaux after the first 10 cases, however the HBP learning curve is longer with continued improvement over the first 30 cases. The shorter learning curve of LBBAP in conjunction with the superior electrical parameters and simplified programming mean the establishment of a CSP program is potentially easier with LBBAP compared to with HBP.

Results of Using Various Conduction System Pacing Options in Patients with Bradyarrhythmia

Chronic right ventricular myocardial pacing causes an asynchronous pattern of left ventricular activation, reduces left ventricular ejection fraction (LVEF), and may be associated with worsening of clinical outcomes in the long term. Although with the emergence of algorithms that minimize ventricular pacing it became possible to reduce the percentage of paced complexes in patients with sinus node dysfunction, permanent ventricular pacing is still inevitable in patients with high-degree atrioventricular (AV) block. The use of permanent conduction system pacing is a promising method for preserving the physiological activation of the ventricular myocardium and preventing the development of heart failure due to ventricular dyssynchrony. The aim. To analyze the immediate and long-term results of the use of conduction system pacing in patients with indications for permanent ventricular pacing. Materials and methods. This study included 18 patients with indications for permanentventricular pacing who were operated at the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine in the period from 01/01/2013 to 12/31/2022, in whom permanent conduction system pacing was used. There were 17 patients with bradyarrhythmias, of these 16 (88%) suffered from high-degree AV block (including 1 patient with Frederick’s syndrome and 1 (5%) patient with atrial ϐibrillation with slow ventricular response) and 1 (5%) patient with ischemic cardiomyopathy with left bundle branch block and ϐirstdegree AV block with indications for cardiac resynchronization therapy. The mean age of the patients was 55 ± 16 years (8 men, 10 women), LVEF at the time of the intervention was 56.42 ± 9.13 %, end diastolic volume 130.2 ± 23.8 ml, end systolic volume 55.1 ± 17.7 ml, diameter of the left atrium 4.01 ± 0.6 cm. The average QRS width before implantation was 116.5 ± 27.7 ms. In 6 (33%) patients, a special delivery system (С304-L69, Medtronic in 1 patient [5%], C315HIS in 5 [27%] patients) and 4.1F active ϐixation lead Medtronic 3830 Select Secure (69 or 74 cm) were used; in other cases (66%) standard 6F leads with active ϐixation and a lumen for a stylet without a delivery system were used. Results. The average follow-up period after implantation of pacemaker was 36.35 ± 29.65 months. During the observation period, LVEF was 57.07 ± 5.38 %, end diastolic volume111.5 ± 18.09 ml, end systolic volume 49.5 ± 13.4 ml, diameter of the left ventricle 3.9 ± 0.5 cm. The mean duration of paced QRS was 119.1 ± 10.09 ms. In 6 patients (33%), it was possible to demonstrate a change in the QRS width when the amplitude of ventricular stimulation was reduced, with 2 variants of transitions: 1) 4 (22%) patients with a transition from non-selective His bundle pacing (NSHBP) to selective His bundle pacing (SHBP), in 2 (11%) of these patients with a transition from SHBP with correction of right bundle branch block (RBBB) to SHBP without correction of RBBB, and then loss of capture of the myocardium of the ventricles; 2) 2 patients (11%) with a transition from NSHBP to myocardial septal ventricular pacing and further with a decrease in amplitude to the loss of capture of the myocardium of the ventricles. One (5%) patient with complete heart block had permanent non-selective left bundle branch area pacing. The other 11 (61%) patients met the criteria for parahisian pacing without visible transitions with a change in the amplitude of ventricular pacing. The average global longitudinal strain was -17.6 ± 2.7 %. The average interval from the stimulus to the peak of the R-wave in lead V6, which indicated the time of left ventricular activation, was 73.2 ± 8.7 ms. Pacing parameters were standardly set according to the primary indications, but with correction of the amplitude of ventricular stimulation relative to the thresholds of pacing of the conduction system. AV delay was corrected for the latency from the stimulus to the onset of the QRS in SHBP or for the duration of the “pseudodelta” wave in NSHBP which in both cases was the duration of the H-V interval. There were no complications in the acute or long-term postoperative period. Conclusions. Conduction system pacing is a challenge in the practice of cardiologist for treating life-threatening bradyarrhythmias and heart failure, but at the same time it is a safe method that provides physiological electrical and mechanical activation of the myocardium of the ventricles, that allows to effectively avoid the consequences of dyssynchrony due to permanent myocardial ventricular pacing.

Conduction system pacing in everyday clinical practice: EHRA physician survey

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

Biventricular versus Conduction System Pacing after Atrioventricular Node Ablation in Heart Failure Patients with Atrial Fibrillation

Conduction system pacing (CSP) modalities, including His-bundle pacing (HBP) and left bundle branch pacing (LBBP), are increasingly used as alternatives to biventricular (BiV) pacing in heart failure (HF) patients scheduled for pace and ablate strategy. The aim of the study was to compare clinical outcomes of HF patients with refractory AF who received either BiV pacing or CSP in conjunction with atrio-ventricular node ablation (AVNA). Fifty consecutive patients (male 48%, age 70 years (IQR 9), left ventricular ejection fraction (LVEF) 39% (IQR 12)) were retrospectively analysed. Thirteen patients (26%) received BiV pacing, 27 patients (54%) HBP and 10 patients (20%) LBBP. All groups had similar baseline characteristics and acute success rate. While New York Heart. Association (NYHA) class improved in both HBP (p < 0.001) and LBBP (p = 0.008), it did not improve in BiV group (p = 0.096). At follow-up, LVEF increased in HBP (form 39% (IQR 15) to 49% (IQR 16), p < 0.001) and LBBP (from 28% (IQR 13) to 40% (IQR 13), p = 0.041), but did not change in BiV group (p = 0.916). Conduction system pacing modalities showed superior symptomatic and echocardiographic improvement compared to BiV pacing after AVNA. With more stable pacing parameters, LBBP could present a more feasible pacing option compared to HBP.