Feasibility and efficacy of left bundle branch area pacing in patients indicated for cardiac resynchronization therapy

Left Bundle Branch Area Pacing versus Biventricular Pacing for Cardiac Resynchronization Therapy on Morbidity and Mortality

BACKGROUND

Left bundle branch area pacing (LBBAP) has emerged as an alternative to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT). We aimed to compare the morbidity and mortality associated with LBBAP versus BVP in patients undergoing CRT implantation.

METHODS

Consecutive patients who received CRT from two high-volume implantation centers were retrospectively recruited. The primary endpoint was a composite of all-cause death and heart failure hospitalization, and the secondary endpoint was all-cause death.

RESULTS

A total of 491 patients receiving CRT (154 via LBBAP and 337 via BVP) were included, with a median follow-up of 31 months. The primary endpoint was reached by 21 (13.6%) patients in the LBBAP group, as compared with 74 (22.0%) patients in the BVP group [hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.43-1.14, P = 0.15]. There were 10 (6.5%) deaths in the LBBAP group, as compared with 31 (9.2%) in the BVP group (HR 0.91, 95% CI 0.44-1.86, P = 0.79). No significant difference was observed in the risk of either the primary or secondary endpoint between LBBAP and BVP after multivariate Cox regression (HR 0.74, 95% CI 0.45-1.23, P = 0.24, and HR 0.77, 95% CI 0.36-1.67, P = 0.51, respectively) or propensity score matching (HR 0.72, 95% CI 0.41-1.29, P = 0.28, and HR 0.69, 95% CI 0.29-1.65, P = 0.40, respectively).

CONCLUSION

LBBAP was associated with a comparable effect on morbidity and mortality relative to BVP in patients with indications for CRT.

Optimizing Patient Selection for Physiological Pacing in Bradyarrhythmia: Factors Associated With High Ventricular Pacing Burden

Background

Right ventricular (RV) pacing is established as the most common ventricular pacing (VP) strategy for patients with symptomatic bradyarrhythmia. Some patients with high VP burden suffer deterioration of left ventricular (LV) function, termed pacing-induced cardiomyopathy (PICM). Patients who pace > 20% of the time from the RV apex are at increased risk of PICM, but independent predictors of increased RV pacing burden have not been elucidated in those who have a permanent pacemaker (PPM) inserted for bradyarrhythmia.

Methods

We aimed to identify factors that are associated with increased VP burden > 20%, hence determining those at risk for resultant PICM. In this retrospective cohort study, we identified the most recent 300 consecutive cardiac implantable electronic device (CIED) implants in our center and collected past medical history, electrocardiogram (ECG), echo, medication and pacemaker check data.

Results

A total of 236 individuals met inclusion criteria. Of the patients, 35% had RV pacing burden < 20%, while 65% had VP burden ≥ 20%; 96.2% of patients with complete heart block (CHB) paced > 20% (P = 0.002). Utilization of DDD or VVI (75.2% and 89.2% of patients, respectively) without mode switch algorithms was associated with VP > 20% (P < 0.001). Male or previous coronary artery bypass grafting (CABG) patients also statistically paced > 20%. Other factors trending towards significance included prolonged PR interval, atrial fibrillation or more advanced age.

Conclusion

High-grade atrioventricular (AV) block was associated with an RV pacing burden > 20% over 3 years but this was not consistent in patients with only transient episodes of high-grade AV block. We found a significant association between high VP% and male sex, previous CABG and the absence of mode switching algorithms.

Cardiac magnetic resonance-derived myocardial scar is associated with echocardiographic response and clinical prognosis of left bundle branch area pacing for cardiac resynchronization therapy

AIMS

Left bundle branch area pacing (LBBAP) is a novel approach for cardiac resynchronization therapy (CRT), but the impact of myocardial substrate on its effect is poorly understood. This study aims to assess the association of cardiac magnetic resonance (CMR)-derived scar burden and the response of CRT via LBBAP.

METHODS AND RESULTS

Consecutive patients with CRT indications who underwent CMR examination and successful LBBAP-CRT were retrospectively analysed. Cardiac magnetic resonance late gadolinium enhancement was used for scar assessment. Echocardiographic reverse remodelling and composite outcomes (defined as all-cause death or heart failure hospitalization) were evaluated. The echocardiographic response was defined as a ≥15% reduction of left ventricular end-systolic volume. Among the 54 patients included, LBBAP-CRT resulted in a 74.1% response rate. The non-responders had higher global, septal, and lateral scar burden (all P < 0.001). Global, septal, and lateral scar percentage all predicted echocardiographic response [area under the curve (AUC): 0.857, 0.864, and 0.822; positive likelihood ratio (+LR): 9.859, 5.594, and 3.059; and negative likelihood ratio (-LR): 0.323, 0.233, and 0.175 respectively], which was superior to QRS morphology criteria (Strauss left bundle branch abnormality: AUC: 0.696, +LR 2.101, and -LR 0.389). After a median follow-up time of 20.3 (11.5-38.7) months, higher global, lateral and septal scar burdens were all predictive of the composite outcome (hazard ratios: 4.996, 7.019, and 4.741, respectively; P's < 0.05).

CONCLUSION

Lower scar burden was associated with higher response rate of LBBAP-CRT. The pre-procedure CMR scar evaluation provides further useful information to identify potential responders 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.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Pacing of Specialized Conduction System

Right ventricular pacing for bradycardia remains the mainstay of pacing therapy. Chronic right ventricular pacing may lead to pacing-induced cardiomyopathy. We focus on the anatomy of the conduction system and the clinical feasibility of pacing the His bundle and/or left bundle conduction system. We review the hemodynamics of conduction system pacing, the techniques to capture the conduction system and the electrocardiogram and pacing definitions of conduction system capture. Clinical studies of conduction system pacing in the setting of atrioventricular block and after AV junction ablation are reviewed and the evolving role of conduction system pacing is compared with biventricular pacing.

Reverse of left ventricular remodeling in heart failure patients with left bundle branch area pacing: Systematic review and meta-analysis

BACKGROUND

Left bundle branch area pacing (LBBAP) has recently become a promising option for the near-natural restoration of electrical activation. However, the clinical relevance of therapeutic effects in individuals with heart failure with reduced ejection fraction (HFrEF) and dyssynchrony remains unknown.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched from inception until June 2022. Data from each study was combined using a random-effects model, the generic inverse variance method of DerSimonian and Laird, to calculate standard mean differences and pooled incidence ratio, with 95% confidence intervals (CIs).

RESULTS

A total of 772 HFrEF patients were analyzed from 15 observational studies per protocol. The success rate of LBBAP implantation was 94.8% (95% CI 89.9-99.6, I2 = 79.4%), which was strongly correlated with shortening QRS duration after LBBAP implantation, with a mean difference of -48.10 ms (95% CI -60.16 to -36.05, I2 = 96.7%). Over a period of 6-12 months of follow-up, pacing parameters were stable over time. There were significant improvements in left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), left ventricular end-diastolic diameter (LVEDD), and left ventricular end-diastolic volume (LVEDV) with mean difference of 16.38% (95% CI 13.13-19.63, I2 = 90.2%), -46.23 ml (95% CI -63.17 to -29.29, I2 = 86.82%), -7.21 mm (95% CI -9.71 to -4.71, I2 = 84.6%), and -44.52 ml (95% CI -64.40 to -24.64, I2 = 85.9%), respectively.

CONCLUSIONS

LBBAP was associated with improvements in both cardiac function and electrical synchrony. The benefits of LBBAP in individuals with HFrEF and dyssynchrony should be further validated by randomized studies.

Left bundle branch area pacing in mildly reduced heart failure: A systematic literature review and meta-analysis

Cardiac resynchronization therapy (CRT) strategy for heart failure with mildly reduced ejection fraction (HFmrEF) is controversial. Left bundle branch area pacing (LBBAP) is an emerging pacing modality and an alternative option to CRT. This analysis aimed to perform a systematic review of the literature and meta-analysis on the impact of the LBBAP strategy in HFmrEF, with left ventricular ejection fraction (LVEF) between 35% and 50%. PubMed, Embase, and Cochrane Library were searched for full-text articles on LBBAP from inception to July 17, 2022. The outcomes of interest were QRS duration and LVEF at baseline and follow-up in mid-range heart failure. Data were extracted and summarized. A random-effect model incorporating the potential heterogeneity was used to synthesize the results. Out of 1065 articles, 8 met the inclusion criteria for 211 mid-range heart failure patients with an implant LBBAP across the 16 centers. The average implant success rate with lumenless pacing lead use was 91.3%, and 19 complications were reported among all 211 enrolled patients. During the average follow-up of 9.1 months, the average LVEF was 39.8% at baseline and 50.5% at follow-up (MD: 10.90%, 95% CI: 6.56-15.23, p < .01). Average QRS duration was 152.6 ms at baseline and 119.3 ms at follow-up (MD: -34.51 ms, 95% CI: -60.00 to -9.02, p < .01). LBBAP could significantly reduce QRS duration and improve systolic function in a patient with LVEF between 35% and 50%. Application of LBBAP as a CRT strategy for HFmrEF may be a viable option.

Leadless Pacing: Therapy, Challenges and Novelties

Leadless pacing is a rapidly growing field. Initially designed to provide right ventricular pacing for those who were contraindicated for conventional devices, the technology is growing to explore the potential benefit of avoiding long-term transvenous leads in any patient who requires pacing. In this review, we first examine the safety and performance of leadless pacing devices. We then review the evidence for their use in special populations, such as patients with high risk of device infection, patients on haemodialysis, and patients with vasovagal syncope who represent a younger population who may wish to avoid transvenous pacing. We also summarise the evidence for leadless cardiac resynchronisation therapy and conduction system pacing and discuss the challenges of managing issues, such as system revisions, end of battery life and extractions. Finally, we discuss future directions in the field, such as completely leadless cardiac resynchronisation therapy-defibrillator devices and whether leadless pacing has the potential to become a first-line therapy in the near future.

Impact of Q wave in synthesized V7-9 lead on long-term outcomes after cardiac resynchronization therapy

BACKGROUND

To investigate the relationship between the Q wave in synthesized V7-9 leads of a baseline electrocardiogram and clinical outcomes in patients with heart failure after cardiac resynchronization therapy (CRT) device implantation.

METHODS

Consecutive patients with heart failure and a left ventricular (LV) ejection fraction <35 % were retrospectively analyzed. Patients with Q waves in the synthesized V7-9 lead were defined as the qV7-9 group and those without Q waves in the synthesized V7-9 lead were defined as the non-qV7-9 group. Multivariate analysis was performed to compare all-cause mortality and incidence of hospitalization for heart failure between the two groups.

RESULTS

We included 108 eligible patients. Twenty-nine patients were classified into the qV7-9 group and 79 patients were classified into the non-qV7-9 group. There were 22 patients (20 %) with ischemic etiology, 67 (62 %) with New York Heart Association functional class II or III heart failure, and 91 (84 %) with a defibrillator. The presence of Q waves in the synthesized V7-9 lead was significantly associated with worse outcomes, even with optimal medical treatment (adjusted hazard ratio, 2.1; 95 % confidence interval, 1.16-3.72; p = 0.03).

CONCLUSION

In patients with heart failure and an LV ejection fraction of <35 %, the presence of Q waves in the synthetic V7-9 lead was associated with increased all-cause mortality and incidence of hospitalization after CRT device implantation.

Left bundle branch area pacing: A promising modality for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is recognized as the first-line management for patients with heart failure (HF) and conduction disorders. As a conventional mode for delivering CRT, biventricular pacing (BVP) improves cardiac function and reduces HF hospitalizations and mortality, but there are still limitations given the high incidence of a lack of response rates. Alternative pacing methods are needed either for primary or rescue therapy. In recent years, conduction system pacing (CSP) has emerged as a more physiological pacing modality for simultaneous stimulation of the ventricles, including His bundle pacing (HBP) and left bundle branch pacing (LBBP). CSP activates the His-Purkinje system, allowing normal ventricular stimulation. However, HBP is technically challenging with a relatively low success rate, high pacing threshold, and failure to correct distal conduction abnormalities. Therefore, LBBP stands out as a novel ideal physiological pacing modality for CRT. Several non-randomized studies compared the feasibility and safety of LBBP with BVP and concluded that LBBP is superior to BVP for delivering CRT with a narrower QRS and greater improvements in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class. Concurrently, some studies showed lower and stable pacing thresholds and greater improvement of B-type natriuretic peptide (BNP) levels, as well as better mechanical synchronization and efficiency. LBBP ensures better ventricular electromechanical resynchronization than BVP. In this review, we discuss current knowledge of LBBP, compare LBBP with BVP, and explore the potential of LBBP to serve as an alternative primary therapy to realize cardiac resynchronization.

Three-dimensional electroanatomical mapping guidelines for the selection of pacing site to achieve cardiac resynchronization therapy

Objectives

We aimed to evaluate the feasibility of left ventricular electroanatomical mapping to choose between left bundle branch area pacing (LBBAP) or coronary venous pacing (CVP).

Background

There are several ways to achieve left ventricular activation in cardiac resynchronization therapy (CRT): LBBAP and CVP are two possible methods of delivering CRT. However, the criteria for choosing the best approach remains unknown.

Methods

A total of 71 patients with heart failure, reduced ejection fraction, and left bundle branch block (LBBB) were recruited, of which 38 patients underwent the three-dimensional electroanatomical mapping of the left ventricle to accurately assess whether the left bundle branch was blocked and the block level, while the remaining 33 patients were not mapped. Patients with true LBBB achieved CRT by LBBAP, while patients with pseudo-LBBB achieved CRT by CVP. After a mean follow-up of 6 months and 1 year, the QRS duration and transthoracic echocardiography, including mechanical synchrony indices, were evaluated.

Results

Twenty-five patients with true LBBB received LBBAP, while 13 without true LBBB received CVP. Seventeen patients received LBBAP, and 16 patients received CVP without mapping. Paced QRS duration after the implantation of LBBAP and CVP was significantly narrower in the mapping subgroup compared to the non-mapping subgroup. A significant increase in post-implantation left ventricular ejection fraction was observed in patients with LBBAP or CVP, and the mapping subgroup were better than the non-mapping subgroup. After a 12-month follow-up, atrioventricular, intraventricular, and biventricular synchronization were significantly improved in the mapping subgroup compared to non-mapping groups in both LBBAP and CVP.

Conclusion

In our study, three-dimensional electroanatomical mapping was used to choose LBBAP or CVP for heart failure patients, which proved feasible, with better cardiac resynchronization in the long-term follow-up. Therefore, three-dimensional electroanatomical mapping before CRT appears to be a reliable method for heart failure patients with LBBB who are indicated for CRT.

Long-term follow-up results of patients with left bundle branch pacing and exploration for potential factors affecting cardiac function

Background: Left bundle branch pacing (LBBP) is an alternative strategy for His bundle pacing (HBP). This study aimed to analyze the long-term performance of LBBP and the potential factors affecting long-term cardiac function.

Methods: Patients with LBBP were continuously enrolled from January 2018 to August 2020. Pacing parameters, electrocardiogram (ECG), and echocardiography were collected. The anatomic position of LBBP leads was described by echocardiographic and fluoroscopic parameters.

Results: A total of 91 patients with a median follow-up of 18 months were enrolled. Most patients maintained stable pacing parameters during follow-up. The intra-septal position of the 3830 lead also remained stable as the distance from the lead tip to the left surface of the ventricular septum was 0.4 (0, 1.4) mm. The overall level of left ventricular ejection fraction (LVEF) slightly increased. 59 patients had improved LVEF (∆LVEF &gt; 0), while 28 patients had unchanged or reduced LVEF (∆LVEF ≤ 0). The declines of baseline LVEF, ∆ Paced QRSd, and corrected longitudinal distance (longit-dist) of lead-implanted site correlated with LVEF improvement, and these three factors had negative linear correlations with ∆LVEF. Patients with tricuspid valve regurgitation (TVR) deterioration had longer follow-up duration (20.5 vs. 15.0 months, p = 0.01) and shorter Lead-TVA-dist (18.6 vs. 21.6 mm, p = 0.04) than those without TVR deterioration.

Conclusion: Patients with LBBP generally remained stable in pacing performance, anatomic lead positions, and cardiac function in long-term follow-up. Baseline LVEF, ∆ Paced QRSd, and corrected longit-dist might be associated with potential LVEF decrease, which required further confirmation.

Quantitative distance and electrocardiographic parameters for lead-implanted site selection to enhance the success likelihood of left bundle branch pacing

BACKGROUND

Left bundle branch pacing (LBBP) is a novel near-physiological pacing method that still lacks quantitative criteria to guide the selection of lead-implanted sites to enhance the success likelihood of lead deployments. This study aimed to quantitatively analyze the relationships of LBBP success likelihood to the distribution of lead-implanted sites and the lead-localization-pacing electrocardiographic (ECG) features.

METHODS

All the lead-implanted sites in patients with finally successful LBBP were enrolled for analysis, including successful and failed sites. A novel coordinate system was invented to describe the sites' distribution as longitudinal distance (longit-dist) and lateral distance (lat-dist). Corrected distance parameters were generated to eliminate the cardiac dimension variations. The lead-localization-pacing ECG parameters were also collected, such as paced QRS duration (locat-QRSd), left ventricular activation time (locat-LVAT), LVAT/QRSd ratio (locat-LVAT/QRSd), and QRS directions.

RESULTS

A total of 94 patients with 105 successful sites and 93 failed sites were enrolled. Longit-dist and corrected longit-dist of successful sites were significantly longer, while locat-QRSd and locat-LVAT were shorter and locat-LVAT/QRSd was lower than failed sites. There was a positive dose-response relationship between LBBP success likelihood and corrected longit-dist with a cut-off of 26.95 mm, whereas there were negative dose-response relationships of LBBP success likelihood to locat-QRSd, locat-LVAT, and locat-LVAT/QRSd with the cut-offs of 142 ms, 92 ms, and 64.7%, respectively. Downward QRS direction in II/III ECG leads was also associated with successful LBBP.

CONCLUSION

Longit-dist, locat-QRSd, locat-LVAT, and locat-LVAT/QRSd were quantitative parameters to guide the selection of lead-implanted sites during LBBP implantation. Quantitative distance and electrocardiographic parameters for lead-implanted site selection to enhance the success likelihood of left bundle branch pacing. LBBP, left bundle branch pacing; Longit-dist, longitudinal distance; CL-apex-dist, distance from contraction line to apex; LBBB, left bundle branch block; IVCD, intraventricular conduction delay; Locat-QRSd, lead-localization-pacing QRS duration; Locat-LVAT, lead-localization-pacing left ventricular activation time; Locat-LVAT/QRSd, lead-localization-pacing LVAT/QRSd ratio.

Pacing of Specialized Conduction System

Right ventricular pacing for bradycardia remains the mainstay of pacing therapy. Chronic right ventricular pacing may lead to pacing-induced cardiomyopathy. We focus on the anatomy of the conduction system and the clinical feasibility of pacing the His bundle and/or left bundle conduction system. We review the hemodynamics of conduction system pacing, the techniques to capture the conduction system and the electrocardiogram and pacing definitions of conduction system capture. Clinical studies of conduction system pacing in the setting of atrioventricular block and after AV junction ablation are reviewed and the evolving role of conduction system pacing is compared with biventricular pacing.

Left Bundle Branch Area Pacing: Implant Technique, Definitions, Outcomes, and Complications

PURPOSE OF REVIEW

Conduction system pacing (CSP) has emerged during the last few years as the cornerstone of physiological pacing. Two different CSP modalities have been described so far: His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). This review will be focused on the description of LBBAP technique, definitions, outcomes, and complications.

RECENT FINDINGS

Large observational studies have demonstrated the safety and feasibility of LBBAP in different scenarios. LBBAP has been associated with excellent pacing electrical parameters (pacing threshold and R wave sensing) and low complication rates including lead revision < 1%. In patients with cardiac resynchronization therapy (CRT) indication, LBBAP has shown significant improvement of functional class and left ventricular ejection fraction during short-term follow-up. LBBAP is a relatively new CSP modality showing excellent results for patients with conventional bradycardia pacing indications and promising expectations about its potential role for CRT.

Outcomes of Left Bundle Branch Area Pacing for Cardiac Resynchronization Therapy: An Updated Systematic Review and Meta-analysis

BACKGROUND

Real-world data on the use of left bundle branch area pacing (LBBAP) as an alternative novel pacing strategy to biventricular pacing (BVP) for cardiac resynchronization therapy (CRT) remains scarce. We aimed to investigate the outcomes of LBBAP as an alternative to BVP as a method of CRT.

METHODS

Electronic databases were searched for studies on the use of LBBAP as CRT and studies that compared LBBAP with BVP. The main outcomes examined were changes in New York Heart Association classification, left ventricular end-diastolic diameter, left ventricular ejection fraction, and paced QRS duration post CRT device implantation.

RESULTS

Our meta-analysis included 8 nonrandomized studies with a total of 527 patients who underwent LBBAP as CRT. In studies with a BVP comparison group, patients with LBBAP had a greater reduction in paced QRS (mean difference [MD], 27.91 msec; 95% confidence interval [CI], 22.33-33.50), and a greater improvement in New York Heart Association class (MD, 0.59; 95% CI, 0.28-0.90) and left ventricular ejection fraction (MD, 6.77%; 95% CI, 3.84-9.71). Patients with underlying left bundle branch block appeared to benefit the most from LBBAP compared with patients without underlying left bundle branch block.

CONCLUSIONS

LBBAP might be a reasonable option for patients who meet indications for CRT, particularly in those who have limited anatomy or do not benefit from CRT. Randomized trials are needed to compare LBBAP with BVP for CRT and to identify which populations might benefit the most from LBBAP.