Left bundle branch pacing vs biventricular pacing in heart failure patients with left bundle branch block: A systematic review and meta-analysis

Sex Specific Outcomes With Cardiac Resynchronization Therapy in Patients With Symptomatic Heart Failure Having Reduced Left Ventricular Ejection Fraction: A Systematic Review and Meta-Analysis

Cardiac resynchronization therapy (CRT) has emerged instrumental in managing heart failure. Notably, there is a lack of evidence of CRT efficacy among both sexes. Thus, this meta-analysis focuses on the long-term benefits of CRT in both sexes. PubMed, The Cochrane Library and clinicaltrials.gov were searched for articles from 2010 to 2024. ROB2 was used to assess risk of bias of RCTs. Newcastle Ottawa Scale was used for quality appraisal of cohorts. Meta-analysis was conducted on Revman 5.4. Out of 2722 articles, only 9 RCTs and 18 cohorts were included. Our results demonstrated that females had a significantly lower risk of composite outcomes compared to males in both RCTs (RR 0.80; 95% CI [0.68, 0.94], P = .006) and cohorts (RR 0.76; 95% CI [0.63, 0.92], P = .004). Results were similar for all-cause mortality. For heart failure hospitalization, only cohorts showed a significant lesser risk in females (RR 0.78; 95% CI [0.65, 0.93], P = .006). Left ventricular ejection fraction improved significantly in females but no differences were observed for NYHA class improvement. Males showed a 31% lower survival rate. However future trials are needed to highlight this variation.

Left bundle branch area pacing compared with biventricular pacing for cardiac resynchronization therapy in patients with left ventricular ejection fraction ≤50%: Results from the International Collaborative LBBAP Study (I-CLAS)

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is an established treatment of heart failure with reduced ejection fraction and wide QRS. Left bundle branch area pacing (LBBAP) has emerged as a physiologic alternative by directly engaging the His-Purkinje system, potentially improving electrical resynchronization and clinical outcomes.

OBJECTIVE

The aim of the study was to compare the clinical outcomes between BVP and LBBAP in patients with left ventricular ejection fraction (LVEF) ≤50% undergoing CRT.

METHODS

This multicenter observational study included patients with LVEF ≤50% receiving CRT with either LBBAP or BVP at 18 centers from January 2018 to June 2023. The primary outcome was a composite of all-cause mortality or first heart failure hospitalization (HFH). Secondary outcomes included separate analyses of HFH and all-cause mortality. Propensity score matching was used to balance baseline characteristics. Kaplan-Meier curves, Cox proportional hazards models, and competing risk analyses were performed.

RESULTS

A total of 2579 patients were included (BVP, 1118; LBBAP, 1461). In the propensity score-matched cohort (BVP, 780; LBBAP, 780), LBBAP demonstrated shorter paced QRS duration (129 ± 19 ms vs 143 ± 22 ms; P < .001). LBBAP was associated with a significantly lower risk of the composite primary outcome (hazard ratio [HR], 0.81; 95% confidence interval [CI], 0.66-0.98; P = .048) and reduced HFH (HR, 0.63; 95% CI, 0.49-0.82; P < .001). No significant difference in all-cause mortality was observed (HR, 0.82; 95% CI, 0.63-1.07; P = .156). Procedural complications were lower with LBBAP (3.5% vs 6.5%, P = .004).

CONCLUSION

LBBAP was associated with superior electrical resynchronization, fewer HFHs, and lower procedural complications compared with BVP in patients with LVEF <50% requiring CRT. Randomized trials are needed to confirm long-term benefits.

Left bundle branch pacing cardiac resynchronization therapy vs biventricular pacing cardiac resynchronization therapy–time to write a requiem for biventricular pacing-cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) reduces heart failure (HF) hospitalizations and all-cause mortality in patients with HF with reduced ejection fraction with left bundle branch (LBB) block. Biventricular pacing (BVP) is considered the gold standard for achieving CRT; however, approximately 30%–40% of patients do not respond to BVP-CRT. Recent studies have demonstrated that LBB pacing (LBBP) produces remarkable results in CRT. In this meta-analysis, LBBP-CRT showed better outcomes than conventional BVP-CRT, including greater QRS duration reduction and left ventricular ejection fraction improvement, along with consistently lower pacing thresholds on follow-up. Additionally, there was a greater reduction in New York Heart Association class and brain natriuretic peptide levels. This study contributes to the growing body of encouraging data on LBBP-CRT from recent years. With ongoing technological advancements and increasing operator expertise, the day may not be far when LBBP-CRT becomes the standard of care rather than the exception.

Dual-chamber pacing confers better myocardial performance and improves clinical outcomes compared to single-chamber pacing

The deleterious effects of long term right ventricular pacing are increasingly being recognized today. Current clinical practice favors the implantation of dual-chamber permanent pacemaker which maintains atrioventricular synchrony and is associated with better quality of life. However, despite the popular belief and common sense surrounding the superiority of dual-chamber pacing over single chamber pacing, the same has never been conclusively verified in clinical trials. Some observational evidence however, does exists which supports the improved cardiac hemodynamics, lower the rate of atrial fibrillation, heart failure and stroke in dual-chamber pacing compared to single-chamber pacing. In the index study by Haque et al, right ventricular pacing, particularly in ventricular paced, ventricular sensed, inhibited response and rate responsive pacemaker adversely impacted the left ventricular functions over 9-months compared to dual pacing, dual sensing, dual responsive and rate responsive pacemaker. Although there are key limitations of this study, these findings does support a growing body of evidence reinstating the superiority of dual chamber pacing compared to single chamber pacing.

Left bundle branch area pacing: A new era of cardiac resynchronization therapy?

The recent systematic review and meta-analysis provided a comprehensive focus on the current state of cardiac resynchronization therapy (CRT). The authors determined the feasibility of physiological left bundle branch area pacing (LBBAP) in patients indicated for CRT through a careful analysis of trials. They found that LBBAP was associated with significant reductions in QRS duration, New York Heart Association functional class, B-type natriuretic peptide levels, and pacing thresholds as well as improvements in echocardiographic parameters compared to biventricular pacing.

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.

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

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