Long-term outcomes of left bundle branch area pacing versus biventricular pacing in patients with heart failure and complete left bundle branch block

Left bundle branch area pacing in heart failure: A systematic review and meta-analysis with meta-regression

INTRODUCTION

Left bundle branch area pacing is an alternative to biventricular pacing. In this study, we aim to summarize the available evidence on the feasibility, efficacy, and safety of left bundle branch block area pacing (LBBAP).

OBJECTIVES

The study summarizes the available evidence on the feasibility, efficacy, and safety of left bundle branch block area pacing (LBBAP).

BACKGROUND

Cardiac resynchronization therapy (CRT) reduced mortality and hospitalizations in heart failure (HF) patients with a left ventricular ejection fraction (LVEF) ≤ 35% and concomitant LBBB. Recently LBBAP has been studied as a more physiological alternative to achieve CRT.

METHOD

A search of PubMed, EMBASE, and Cochrane databases were performed to identify studies examining the role of LBBAP for CRT in heart failure. Comprehensive meta-analysis version 4 was used for meta-regression to examine variables that contribute to data heterogeneity.

RESULT

Eighteen studies, 17 observational and one randomized controlled trial (RCT) were examined. A total of 3906 HF patients who underwent CRT (2036 LBBAP vs. 1870 biventricular pacing [BVP]) were included. LBBAP was performed successfully in 90.4% of patients. Compared to baseline, LBBAP was associated with a reduction in QRS duration (MD: -47.23  ms 95% confidence interval [CI]: -53.45, -41.01), an increase in LVEF (MD: 15.22%, 95% CI: 13.5, 16.94), and a reduction in NYHA class (MD: -1.23, 95% CI: -1.41, -1.05). Compared to BVP, LBBAP was associated with a significant reduction in QRS duration (MD: -20.69 ms, 95% CI: -25.49, -15.88) and improvement in LVEF (MD: 4.78%, 95% CI: 3.30, 6.10). Furthermore, LBBAP was associated with a significant reduction in HF hospitalization (odds ratio [OR]: 0.44, 95% CI: 0.34, 0.56) and all-cause mortality (OR: 0.67, 95% CI: 0.52, 0.86) compared to BVP.

CONCLUSION

LBBAP was associated with improved ventricular electrical synchrony compared to BVP, as well as better echocardiographic and clinical outcomes.

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

INTRODUCTION

Cardiac resynchronization therapy (CRT) with biventricular pacing (BiV-CRT) is ineffective in approximately one-third of patients. CRT with Conduction system pacing (CSP-CRT) may achieve greater synchronization. We aimed to assess the effectiveness of CRT with His pacing (His-CRT) or left bundle branch pacing (LBB-CRT) in lieu of biventricular CRT.

METHODS AND RESULTS

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

CONCLUSION

This study found that CSP-CRT is associated with greater improvements in QRSd, echocardiographic, and clinical response. LBB-CRT was associated with lower pacing thresholds. Future randomized trials are needed to determine CSP-CRT efficacy.

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

Background

Left bundle branch area pacing (LBBAP) may offer greater physiological benefits than traditional biventricular pacing (BiVP). However, there are limited data comparing the efficacy of LBBAP vs BiVP in patients with systolic heart failure (HF).

Objective

The purpose of this meta-analysis was to compare the feasibility and electromechanical and clinical outcomes of both LBBAP and BiVP.

Methods

We conducted a systematic review of studies retrieved from various databases including PubMed, Embase, Google Scholar, Scopus, and Cochrane Central Register of Control Trials (CENTRAL) published up to May 22, 2023. The risk ratio (RR) and standardized mean difference (SMD) with corresponding 95% confidence intervals (CIs) were calculated for dichotomous and continuous outcomes, respectively.

Results

We included 12 studies with a total of 3004 patients (LBBAP = 1242, BiVP = 1762). Pooled results showed that LBBAP resulted in a significant increase in left ventricular ejection fraction (SMD 0.40, 95% CI 0.25, 0.54, P < .00001), echocardiographic response (RR 1.19, 95% CI 1.10 to 1.29, P < .0001), improvement in New York Heart Association functional class (SMD -0.44, 95% CI -0.65 to -0.23, P < .0001), QRS duration reduction (SMD -0.90, 95% CI -1.14 to -0.66, P < .00001), left ventricular end-diastolic diameter reduction (SMD -0.31, 95% CI -0.57 to -0.05, P = .02), fewer HF hospitalizations (RR 0.72, 95% CI 0.62, 0.85, P < .0001), and improved survival (RR 0.73, 95% CI 0.58, 0.92, P = .007). In addition, LBBAP was associated with shorter fluoroscopy time (SMD -0.94, 95% CI -1.42 to -0.47, P < .0001) and lower pacing threshold at implantation (SMD -1.03, 95% CI -1.32 to -0.74, P < .00001) and at 6 months (SMD -1.44, 95% CI -2.11 to -0.77, P < .0001) as compared with BiVP.

Conclusion

Compared with BiVP, LBBAP was associated with better electromechanical and clinical outcomes, including left ventricular ejection fraction, QRS duration, echocardiographic response, New York Heart Association functional class, HF hospitalization, and all-cause mortality in patients with systolic HF.

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

INTRODUCTION

Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT.

METHODS

We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2  > 50% indicating significant heterogeneity.

RESULTS

Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2  = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2  = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2  = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2  = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2  = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2  = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2  = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2  = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2  = 0%, p = .87).

CONCLUSION

This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

Clinical outcomes of conduction system pacing versus biventricular pacing for cardiac resynchronization therapy: A systematic review and meta-analysis

INTRODUCTION

Conduction system pacing (CSP) is observed to produce greater improvements in echocardiographic and hemodynamic parameters as compared to conventional biventricular pacing (BiVP). However, whether these surrogate endpoints directly translate to improvements in hard clinical outcomes such as death and heart failure hospitalization (HFH) with CSP remains uncertain as studies reporting these outcomes are scarce. The aim of this meta-analysis was to analyze the existing data to compare the clinical outcomes of CSP versus BiVP.

METHODS

A systematic search of the Embase and PubMed database was performed for studies comparing CSP and BiVP for patients indicated to receive a CRT device. The coprimary endpoints were all-cause mortality and HFH. Other secondary outcomes included change in left ventricular ejection fraction (LVEF), change in NYHA class, and increase in NYHA class ≥1. A random-effects model was chosen a priori to analyze the composite effects given the anticipated heterogeneity of included trials.

RESULTS

Twenty-one studies (4 randomized and 17 observational) were identified reporting either primary outcome and were included in the meta-analysis. In total 1960 patients were assigned to CSP and 2367 to BiVP. Median follow-up time was 10.1 months (ranging 2-33 months). CSP was associated with a significant reduction in all-cause mortality (odds ratio [OR] 0.68, 95% confidence interval [CI]: 0.56-0.83) and HFH (OR 0.52, 95% CI: 0.44-0.63). Mean improvement in LVEF was also greater with CSP (mean difference 4.26, 95% CI: 3.19-5.33). Reduction in NYHA class was significantly greater with CSP (mean difference -0.36, 95% CI: -0.49 to -0.22) and the number of patients with an increase in NYHA class ≥1 was significantly greater with CSP (OR 2.02, 95% CI: 1.70-2.40).

CONCLUSIONS

CSP was associated with a significant reduction in all-cause mortality and HFH when compared to conventional BiVP for CRT. Further large-scale randomized trials are needed to verify these observations.

His-Purkinje system pacing versus biventricular pacing in clinical efficacy: a systematic review and meta-analysis

BACKGROUND

His-Purkinje system pacing (HPSP), including his-bundle pacing (HBP) and left bundle branch area pacing (LBBaP), imitates the natural conduction of the heart as an alternative to biventricular pacing (BVP) in cardiac resynchronization therapy (CRT). However, the feasibility and efficacy of HPSP were currently only evidenced by studies with a limited sample size, so this study aimed to provide a comprehensive assessment through a systematic review and meta-analysis.

METHODS

In order to compare the clinical outcomes associated with HPSP and BVP in patients for CRT, PubMed, EMBASE, Cochrane Library and Web of Science database were searched from inception to April 10, 2023. Clinical outcomes of interest including QRS duration (QRSd), left ventricular (LV) function and New York Heart Association (NYHA) functional classification, pacing threshold, echocardiographic and clinical response, hospitalization rate of HF and all-cause mortality were also extracted and summarized for meta-analysis.

RESULTS

A total of 13 studies (ten observational studies and three randomized studies) involving 1,121 patients were finally included. The patients were followed up for 6-27 months. Compared with BVP, CRT patients treated by HPSP presented shorter QRSd [mean difference (MD): -26.23 ms, 95% confidence interval (CI): -34.54 to -17.92, P < 0.001, I² = 91%], greater LV functional improvement with increased left ventricular ejection fraction (LVEF) (MD: 6.01, 95% CI: 4.81 to 7.22, P < 0.001, I² = 0%), decreased left ventricular end-diastolic dimension (LVEDD) (MD: -2.91, 95% CI: -4.86 to -0.95, P = 0.004, I² = 35%), and more improved NYHA functional classification (MD: -0.45, 95% CI: -0.67 to -0.23, P < 0.001, I² = 70%). In addition, HPSP was more likely to have higher echocardiographic [odds ratio (OR): 2.76, 95% CI: 1.74 to 4.39, P < 0.001, I² = 0%], clinical (OR: 2.10, 95% CI: 1.16 to 3.80, P = 0.01, I² = 0%) and super clinical (OR: 3.17, 95% CI: 2.09 to 4.79, P < 0.001, I² = 0%) responses than BVP, and a lower hospitalization rate of HF (OR: 0.34, 95% CI: 0.22 to 0.51, P < 0.001, I² = 0%), while presented no difference (OR: 0.68, 95% CI: 0.44 to 1.06, P = 0.09, I² = 0%) in all-cause mortality compared with BVP. With threshold change taking into account, BVP was less stable than LBBaP (MD: -0.12 V, 95% CI: -0.22 to -0.03, P = 0.01, I² = 57%), but had no difference with HBP (MD: 0.11 V, 95% CI: -0.09 to 0.31, P = 0.28, I² = 0%).

CONCLUSION

The present findings suggested that HPSP was associated with greater improvement of cardiac function in patients with indication for CRT and was a potential alternative to BVP to achieve physiological pacing through native his-purkinje system.

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.

Conduction system pacing is superior to biventricular pacing in patients with heart failure: Insights from the pooled clinical studies

Background: The effects of conduction system pacing (CSP) compared with conventional biventricular pacing (BVP) on heart function in patients with heart failure remain elusive. Methods: PubMed, Embase, Cochrane's Library and Web of science databases were searched up to 1 October 2022 for pertinent controlled studies. Random or fixed-effect model were used to synthesize the clinical outcomes. Subgroup analysis was performed to screen the potential confounding factors. Results: Fifteen studies including 1,347 patients were enrolled. Compared with BVP, CSP was significantly associated with shortened QRS duration [WMD -22.51 ms; p = 0.000], improved left ventricular ejection fraction [WMD 5.53%; p = 0.000], improved NYHA grade [WMD -0.42; p = 0.000], higher response rate and lower heart failure rehospitalization rate. CSP resulted in better clinical outcomes in higher male proportion group than lower one compared with BVP. No significant differences of clinical outcomes were observed between left bundle branch area pacing (LBBaP) and his bundle pacing (HBP) except the pacing threshold. The pacing threshold of LBBaP was significantly lower than those in BVP and HBP. Conclusion: This study suggests that CSP might be superior to conventional BVP for HF patients. In a higher male proportion group, CSP may be associated with more benefits than BVP. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022355991; Identifier: CRD42022355991.

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

INTRODUCTION

Cardiac resynchronization therapy (CRT) reduces heart failure (HF) hospitalization and all-cause mortality in HF patients with left bundle branch block (LBBB). Biventricular pacing (BVP) is the gold standard for achieving CRT, but about 30%-40% of patients do not respond to BVP-CRT. Recent studies showed that left bundle branch pacing (LBBP) provided remarkable results in CRT. Therefore, we conducted a meta-analysis aiming to compare LBBP-CRT versus BVP-CRT in HF patients.

METHODS

We systematically searched the electronic databases for studies published from inception to December 29, 2022 and focusing on LBBP-CRT versus BVP-CRT in HF patients. The primary endpoint was HF hospitalization. The effect size was estimated using a random-effect model as Risk Ratio (RR) and mean difference (MD).

RESULTS

Ten studies enrolling 1063 patients met the inclusion criteria. Compared to BVP-CRT, LBBP-CRT led to significant reduction in HF hospitalization [7.9% vs.14.5%; RR: 0.60 (95%CI: 0.39-0.93); p = .02], QRSd [MD: 30.26 ms (95%CI: 26.68-33.84); p < .00001] and pacing threshold [MD: -0.60 (95%CI: -0.71 to -0.48); p < .00001] at follow up. Furthermore, LBBP-CRT improved LVEF [MD: 5.78% (95%CI: 4.78-6.77); p < .00001], the rate of responder [88.5% vs.72.5%; RR: 1.19 (95%CI: 1.07-1.32); p = .002] and super-responder [60.8% vs. 36.5%; RR: 1.56 (95%CI: 1.27-1.91); p < .0001] patients and the NYHA class [MD: -0.42 (95%CI: -0.71 to -0.14); p < .00001] compared to BVP-CRT.

CONCLUSION

In HF patients, LBBP-CRT was superior to BVP-CRT in reducing HF hospitalization. Further significant benefits occurred within the LBBP-CRT group in terms of QRSd, LVEF, pacing thresholds, NYHA class and the rate of responder and super-responder patients.

A conversion CRT strategy combined with AVJA may be a perspective alternative for heart failure patients with persistent atrial fibrillation

Heart failure (HF) combined with persistent atrial fibrillation (AF) often coexist and may promote the pathological conditions of cardiac dysfunction, leading to poor prognosis. Cardiac resynchronization therapy (CRT) combined with atrioventricular junction ablation (AVJA) is a highly effective treatment for HF patients with underlying AF who either have failed or are not suitable for catheter ablation. The CRT-AVJA combination therapy can improve clinical outcomes in HF patients. Currently, clinical CRT methods are categorized into biventricular pacing (BVP) - based and conduction system pacing (CSP) - based methods. These procedures have inherent advantages and disadvantages, in addition to their considerable differences in clinical applications. This article aims to review the clinical progress of AVJA combined with different CRT strategies for treating HF patients with persistent AF and propose that conversion CRT strategy (BVP/CSP-CRT) combined with AVJA may be a perspective alternative. Meanwhile, we generalize that 7 categories of HF patients with persistent AF may need to consider the CRT-AVJA combination therapy.

Alternative pacing strategies for optimal cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) via biventricular pacing (BVP) improves morbidity, mortality, and quality of life, especially in subsets of patients with impaired cardiac function and wide QRS. However, the rate of unsuccessful or complicated left ventricular (LV) lead placement through coronary sinus is 5–7%, and the rate of “CRT non-response” is approximately 30%. These reasons have pushed physicians and engineers to collaborate to overcome the challenges of LV lead implantation. Thus, various alternatives to BVP have been proposed to improve CRT effectiveness. His bundle pacing (HBP) has been increasingly used by activating the His–Purkinje system but is constrained by challenging implantation, low success rates, high and often unstable thresholds, and low perception. Therefore, the concept of pacing a specialized conduction system distal to the His bundle to bypass the block region was proposed. Multiple clinical studies have demonstrated that left bundle branch area pacing (LBBAP) has comparable electrical resynchronization with HBP but is superior in terms of simpler operation, higher success rates, lower and stable capture thresholds, and higher perception. Despite their well-demonstrated effectiveness, the transvenous lead-related complications remain major limitations. Recently, leadless LV pacing has been developed and demonstrated effective for these challenging patient cohorts. This article focuses on the current state and latest progress in HBP, LBBAP, and leadless LV pacing as alternatives for failed or non-responsive conventional CRT as well as their limits and prospects.

Physiologic Pacing Targeting the His Bundle and Left Bundle Branch: a Review of the Literature

PURPOSE OF REVIEW

Conduction system pacing (CSP) has emerged as a means to preserve or restore physiological ventricular activation via pacing at the His bundle or at more distal targets in the conduction system, including the left bundle branch area. This review examines strengths, weaknesses, and clinical applications of CSP performed via these approaches.

RECENT FINDINGS

His bundle pacing (HBP) has been successfully utilized for standard bradyarrhythmia indications and for QRS correction among patients receiving devices for cardiac resynchronization therapy (CRT). Limitations of HBP pacing have included implant complexity and rising pacing thresholds over time. Left bundle branch area pacing (LBBAP) appears to deliver similar physiological benefits with shorter implant times and more stable thresholds. More recently, hybrid systems utilizing HBP or LBBAP in combination with left ventricular leads have been used to treat heart failure (HF) patients, and may be useful in multilevel or mixed conduction blocks. There is growing interest in CSP for bradycardia and HF indications, although high quality data with randomized controlled trials are needed to help guide future treatment paradigms.