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

Long-Term Follow-Up of Left Bundle Branch Area Pacing in Pacing-Dependent Patients and Normal Cardiac Function

INTRODUCTION

Left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing strategy. The purpose of this study was to evaluate the long-term effect of LBBAP in ventricular pacing-dependent patients and baseline normal cardiac function.

METHODS

This retrospective observational study included patients who underwent LBBAP or RVP for bradycardia indications between January 2018 and July 2021. Baseline characteristics and electrophysiological, pacing and echocardiographic data were collected.

RESULTS

Sixty patients with VP% ≥ 40% were enrolled, including 30 patients in the LBBAP group and 30 patients in the RVP group. The mean follow-up time was 53.03 ± 8.10 months in the LBBAP group and 51.87 ± 11.68 months in the RVP group. No ventricular septum perforation was observed during the procedure or follow-up. The R-wave amplitudes did not differ between the two groups at implantation, but the R-wave amplitude in the LBBAP group at last follow-up was higher than that in the RVP group (17.67 ± 7.50 mV vs. 12.38 ± 5.36 mV, p = 0.003). Paced QRS duration in the LBBAP group was significantly shorter than that in the RVP group (138.93 ± 15.36 ms vs. 164.30 ± 19.48 ms, p < 0.0001). The LBBAP group had a higher LVEF (64.81 ± 5.49 vs. 60.44 ± 9.28, p = 0.041) and lower LVESD (29.70 ± 4.59 mm vs. 32.03 ± 3.97 mm, p = 0.039) than the RVP group at last follow-up.

CONCLUSION

This study found LBBAP electrodes had a stable anatomic position, better pacing parameters, and better maintaining cardiac performances than RVP in patients with normal cardiac function and bradyarrhythmia indications.

The Functional and Imaging Implications of Left Bundle Branch Pacing in Ischemic Cardiomyopathy

Heart failure with reduced ejection fraction due to ischemic cardiomyopathy remains a significant clinical challenge. Electrical conduction delays exacerbate symptoms by causing uncoordinated contractions, reducing pumping efficiency, and increasing mortality. Right ventricular pacing further worsens dyssynchrony, while resynchronization therapy improves outcomes but has a high non-responder rate. Given these limitations, bundle branch pacing engages the heart's conduction system, restoring synchronized contraction and enhancing cardiac function. This review examines the impact of left-bundle-branch-block-induced dyssynchrony, the role of advanced imaging in assessing ventricular function, and the clinical outcomes of bundle branch pacing in heart failure patients. Specifically, we explore the mechanical and hemodynamic effects of left bundle branch block, imaging techniques for dyssynchrony evaluation, and the comparative benefits of bundle branch pacing versus resynchronization therapy. Conduction delays impair function, increase myocardial stress, and worsen clinical outcomes. Advanced imaging plays a critical role in patient selection, identifying those most likely to benefit from conduction system pacing. By restoring electrical coordination, bundle branch pacing enhances ventricular function, reduces hospitalizations, and promotes reverse remodeling. It offers similar or superior benefits to conventional resynchronization therapy, regulates stress hormones, reduces oxidative damage, and improves calcium handling. Bundle branch pacing represents a significant advancement in heart failure management, but careful patient selection remains crucial. Future research should focus on optimizing implantation techniques and validating long-term benefits through large-scale clinical trials.

Recent Advances in Cardiac Resynchronization Therapy: Current Treatment and Future Direction

Cardiac Resynchronization Therapy (CRT) has been established as a major component of heart failure management, resulting in a significant reduction in patient morbidity and death for patients with increased QRS duration, low left ventricular ejection fraction (LVEF), and high risk of arrhythmias. The ability to synchronize both ventricles, lower heart failure hospitalizations, and optimize clinical outcomes are some of the attractive characteristics of biventricular pacing, or CRT. However, the high rate of CRT non-responders has led to the development of new modalities including leadless CRT pacemakers (CRT-P) and devices focused on conduction system pacing (CSP). This comprehensive review aims to present recent findings from CRT clinical trials and systematic reviews that have been published that will likely guide future directions in patient care.

Reverse electrical remodelling after cardiac resynchronization therapy in a patient undergoing left bundle branch area pacing: a case report

Background

Left bundle branch area pacing (LBBAP) has been introduced as an alternative to biventricular pacing in cardiac resynchronization therapy (CRT). Several studies describe echocardiographic reverse remodelling after LBBAP. Reverse electrical remodelling after LBBAP has not yet been described.

Case summary

A 77-year-old female with non-ischaemic heart failure with reduced ejection fraction [left ventricular ejection fraction (LVEF) 30-35%], left bundle branch block (QRS duration 164 ms), and symptomatic atrial fibrillation irresponsive to pharmacological therapy was evaluated for CRT with LBBAP and atrioventricular node ablation. Successful LBBAP implantation resulted in confirmed left bundle branch capture. Immediately after implantation, paced QRS duration was 194 ms with a long stimulus-V6RWPT (time to peak R wave in V6) of 93 ms, suggesting distal conduction system disease. Patient showed an echocardiographic improvement (LVEF 35-50%) and improvement in symptoms (NYHA class III to NYHA class II) at 1-year follow-up. Moreover, an improvement in conduction delays was found present. Paced QRS duration improved to 159 ms and stimulus-V6RWPT improved to 78 ms. This improvement might be due to reverse electrical remodelling.

Discussion

This case demonstrates that LBBAP can induce reverse electrical remodelling, even in the presence of distal conduction system disease. With the current availability of different pacing strategies in CRT (i.e. biventricular CRT, LBBAP, and left bundle branch-optimized CRT), more research on patient selection and pacing strategy selection is needed.

His Bundle Pacing and Left Bundle Branch Pacing in Patients with Heart Failure

BACKGROUND

His bundle pacing (HBP) and left bundle branch pacing (LBBP) are emerging therapies for patients with heart failure and conduction disorders, offering potential advantages over traditional pacing methods. These approaches aim to restore physiological conduction and improve cardiac function more effectively.

OBJECTIVE

This study aims to evaluate the efficacy and safety of HBP and LBBP in patients with heart failure and conduction disturbances, comparing these techniques to conventional pacing.

METHODS

A comprehensive review of recent studies and clinical trials was conducted, focusing on the performance of HBP and LBBP in improving cardiac function, reducing QRS duration, and enhancing overall patient outcomes. The analysis includes data on clinical efficacy, procedural safety, and long-term benefits associated with these pacing modalities.

RESULTS

Both HBP and LBBP have demonstrated significant improvements in cardiac function and clinical outcomes compared to conventional pacing. HBP effectively restores physiological conduction with improved synchronization and a reduction in QRS duration. LBBP has shown enhanced left ventricular activation, leading to better overall cardiac performance. Both techniques have been associated with a lower incidence of complications and a higher success rate in achieving optimal pacing thresholds.

CONCLUSIONS

HBP and LBBP offer promising alternatives to traditional pacing for patients with heart failure and conduction disorders. These advanced pacing strategies provide superior clinical outcomes and improved cardiac function with reduced risk of complications. Further research and clinical trials are needed to fully establish the long-term benefits and safety profiles of these techniques in diverse patient populations.

Metabolic Adaptation in Heart Failure and the Role of Ketone Bodies as Biomarkers

PURPOSE OF REVIEW

The development and progression of heart failure is characterized by metabolic and physiologic adaptations allowing patients to cope with cardiac insufficiency. This review explores the changes in metabolism in heart failure and the potential role of biomarkers, particularly ketone bodies, in staging and prognosticating heart failure progression.

RECENT FINDINGS

Recent insights into myocardial metabolism shed light on the heart's response to stress, highlighting the shift towards reliance on ketone bodies as an alternative fuel source. Elevated blood ketone levels have been shown to correlate with the severity of cardiac dysfunction, emphasizing their potential as prognostic indicators. Furthermore, studies exploring therapeutic interventions targeting specific metabolic pathways offer promise for improving outcomes in heart failure. Ketones have prognostic utility in heart failure, and potentially, an avenue for therapeutic intervention. Challenges remain in deciphering the optimal balance between metabolic support and exacerbating cardiac remodeling. Future research endeavors must address these complexities to advance personalized approaches in managing heart failure.

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.

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.