Left bundle branch–optimized cardiac resynchronization therapy (LOT-CRT): Results from an international LBBAP collaborative study group

doi:10.1016/j.hrthm.2021.07.057

Heart Rhythm

Volume 19, Issue 1, January 2022, Pages 13-21

https://doi.org/10.1016/j.hrthm.2021.07.057 Get rights and content

Background

Cardiac resynchronization therapy (CRT) based on the conventional biventricular pacing (BiV-CRT) technique sometimes results in broad QRS complex and suboptimal response.

Objective

We aimed to assess the feasibility and outcomes of CRT based on left bundle branch area pacing (LBBAP, in lieu of the right ventricular lead) combined with coronary venous left ventricular pacing in an international multicenter study.

Methods

LBBAP-optimized CRT (LOT-CRT) was attempted in nonconsecutive patients with CRT indications. Addition of the LBBA (or coronary venous) lead was at the discretion of the implanting physician, who was guided by suboptimal paced QRS complex, and/or on clinical grounds.

Results

LOT-CRT was successful in 91 of 112 patients (81%). The baseline characteristics were as follows: mean age 70 ± 11 years, female 22 (20%), left ventricular ejection fraction 28.7% ± 9.8%, left ventricular end-diastolic diameter 62 ± 9 mm, N-terminal pro–B-type natriuretic peptide level 5821 ± 8193 pg/mL, left bundle branch block 47 (42%), nonspecific intraventricular conduction delay 25 (22%), right ventricular pacing 26 (23%), and right bundle branch block 14 (12%). The procedure characteristics were as follows: mean fluoroscopy time 27.3 ± 22 minutes, LBBAP capture threshold 0.8 ± 0.5 V @ 0.5 ms, and R-wave amplitude 10 mV. LOT-CRT resulted in significantly greater narrowing of QRS complex from 182 ± 25 ms at baseline to 144 ± 22 ms (P < .0001) than did BiV-CRT (170 ± 30 ms; P < .0001) and LBBAP (162 ± 23 ms; P < .0001). At follow-up of ≥3 months, the ejection fraction improved to 37% ± 12%, left ventricular end-diastolic diameter decreased to 59 ± 9 mm, N-terminal pro–B-type natriuretic peptide level decreased to 2514 ± 3537 pg/mL, pacing parameters were stable, and clinical improvement was noted in 76% of patients (New York Heart Association class 2.9 vs 1.9).

Conclusion

LOT-CRT is feasible and safe and provides greater electrical resynchronization as compared with BiV-CRT and could be an alternative, especially when only suboptimal electrical resynchronization is obtained with BiV-CRT. Randomized controlled trials comparing LOT-CRT and BiV-CRT are needed.

Graphical abstract

Introduction

Left bundle branch area pacing (LBBAP) is a promising physiological pacing technique with potential for application in both patients with bradyarrhythmia and those with heart failure.1, 2, 3, 4 However, proximal left bundle branch (LBB) pacing is inherently limited in its ability to restore physiological activation of the lateral wall of the left ventricle (LV) in patients with distal conduction delay in the distal LBB, LV Purkinje network, or myocardium. Moreover, perhaps in a significant percentage of patients in whom LBBAP was attempted, only left ventricular septal (LVS) myocardial capture was obtained, resulting in a small but potentially important nonphysiological delay in LV lateral wall activation.⁴

Conventional cardiac resynchronization therapy (CRT) using biventricular (BiV) pacing based on right ventricular (RV) pacing and coronary venous (CV) pacing is also limited in its ability to fully restore physiological activation of the LV. Limitations of BiV-CRT are related, among others, to the potentially desynchronizing impact of myocardial pacing with the RV lead, single area nonphysiological epicardial LV pacing, latency, and suboptimal LV lead position (paraseptal/apical) due to the unfavorable anatomy of the cardiac veins and/or LV scars.⁵^,⁶ Failure of BiV-CRT to restore physiological activation might express itself as QRS prolongation rather than narrowing. This is observed in one-third of patients who underwent BiV-CRT and related to poor prognosis.

Combining LBBAP and BiV pacing (Figures 1 and 2) might address some of the above-mentioned limitations of both techniques, providing narrower QRS complex and a more efficient form of CRT, especially in challenging cases and patients with more advanced heart failure.⁷

The aim of the study was to assess the feasibility and outcomes of CRT based on LBBAP (in lieu of the RV lead), combined with CV pacing, in an international multicenter study.

Section snippets

Methods

The data that support the findings of this study are available from the corresponding author on reasonable request. The study adhered to the Helsinki Declaration as revised in 2013; data collection was approved by respective institutional review boards.

Population

A total of 112 patients underwent LOT-CRT at 9 centers. Baseline group characteristics are summarized in Table 1. Briefly, the mean age of patients was 70.5 ± 11 years (20% female) and most patients had ischemic cardiomyopathy (61%) with a mean LVEF of 28.8% ± 9.8%. Seventy-two percent of patients were grouped under NYHA functional class III or IV. The mean follow-up duration in the study population was 7.8 ± 2.3 months. Because of the severe acute respiratory syndrome–related coronavirus

Discussion

This study presents multicenter experience with mid-term follow-up of the LOT-CRT technique in nonconsecutive patients with advanced heart failure and broad QRS complex. It addresses pertinent initial questions related to the rationale behind this new pacing method and provides data on its safety, feasibility, and outcomes.

Conclusion

LOT-CRT is feasible and safe and provides greater electrical resynchronization, compared with BiV-CRT, and could be an alternative to BiV-CRT, especially when only suboptimal electrical resynchronization is obtained with BiV-CRT. Randomized controlled trials comparing LOT-CRT and BiV-CRT are needed.

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Cited by (119)

Left bundle branch pacing lead for sensing ventricular arrhythmias in implantable cardioverter-defibrillator: A pilot study (LBBP-ICD study)
2024, Heart Rhythm
Left bundle branch pacing (LBBP) has been suggested as an alternative modality for biventricular pacing in cardiac resynchronization therapy (CRT)–eligible patients. As it provides stable R-wave sensing, LBBP has been recently used to provide sensing of ventricular arrhythmia in patients receiving implantable cardioverter-defibrillator (ICD) with CRT.
The aim of this study was to analyze the long-term safety and efficacy of the LBBP lead for appropriate detection of ventricular arrhythmia and delivery of antitachycardia pacing (ATP) in patients requiring defibrillator therapy with CRT.
CRT-eligible patients who underwent successful LBBP-optimized ICD and LBBP-optimized CRT with defibrillator were enrolled. The LBBP lead was connected to the right ventricular-P/S port after capping the IS-1 connector plug of the DF-1–ICD lead. LBBP-optimized ICD or LBBP-optimized CRT with defibrillator was decided on the basis of correction of conduction system disease. Documented arrhythmic episodes and therapy delivered were analyzed.
Thirty patients were enrolled. The mean age was 59.7 ± 10.5 years. LBBP resulted in an increase in left ventricular ejection fraction from 29.9% ± 4.6% to 43.9% ± 11.2% (P < .0001). During a mean follow-up of 22.9 ± 12.5 months, 254 ventricular arrhythmic events were documented. Appropriate events (n = 225 [89%]) included nonsustained ventricular tachycardia (VT) (n = 212 episodes [94%]), VT (n = 8 [3.5%]), and ventricular fibrillation (n = 5 [2.5%]). ATP efficacy in terminating VT was 75%. Eleven percent of episodes (n = 29) were inappropriately detected because of T-wave oversensing. Inappropriate therapy (ATP) was delivered for 14 episodes (5.5%). Three patients (10%) had worsening of tricuspid regurgitation.
Sensing from the LBBP lead for arrhythmia detection is safe as ∼90% of the episodes were detected appropriately. Future studies with a dedicated LBBP-defibrillator lead along with algorithms to avoid oversensing can help in combining defibrillation with conduction system pacing.
Left bundle branch pacing vs ventricular septal pacing for cardiac resynchronization therapy
2024, Heart Rhythm O2
The outcomes of left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) in patients with heart failure remain to be learned.
The objective of this study was to assess the echocardiographic and clinical outcomes of LBBP, LVSP, and deep septal pacing (DSP).
This retrospective study included patients who met the criteria for cardiac resynchronization therapy (CRT) and underwent attempted LBBP in 5 Mayo centers. Clinical, electrocardiographic, and echocardiographic data were collected at baseline and follow-up.
A total of 91 consecutive patients were included in the study. A total of 52 patients had LBBP, 25 had LVSP, and 14 had DSP. The median follow-up duration was 307 (interquartile range 208, 508) days. There was significant left ventricular ejection fraction (LVEF) improvement in the LBBP and LVSP groups (from 35.9 ± 8.5% to 46.9 ± 10.0%, P < .001 in the LBBP group; from 33.1 ± 7.5% to 41.8 ± 10.8%, P < .001 in the LVSP group) but not in the DSP group. A unipolar paced right bundle branch block morphology during the procedure in lead V1 was associated with higher odds of CRT response. There was no significant difference in heart failure hospitalization and all-cause deaths between the LBBP and LVSP groups. The rate of heart failure hospitalization and all-cause deaths were increased in the DSP group compared with the LBBP group (hazard ratio 5.10, 95% confidence interval 1.14–22.78, P = .033; and hazard ratio 7.83, 95% confidence interval 1.38–44.32, P = .020, respectively).
In patients undergoing CRT, LVSP had comparable CRT outcomes compared with LBBP.
Right bundle branch activation during left bundle branch pacing: Marginal gains in left bundle branch pacing–optimized cardiac resynchronization therapy and the effects of atrioventricular delay dynamic optimization
2024, HeartRhythm Case Reports
Phase analysis using cadmium-zinc-telluride single photon emission computed tomography for evaluating mechanical synchronization: A case report on left bundle branch–optimized cardiac resynchronization therapy
2024, HeartRhythm Case Reports
Left Bundle Branch Pacing vs Left Ventricular Septal Pacing vs Biventricular Pacing for Cardiac Resynchronization Therapy
2024, JACC: Clinical Electrophysiology
Left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are considered to be acceptable as LBBAP strategies. Differences in clinical outcomes between LBBP and LVSP are yet to be determined.
The purpose of this study was to compare the outcomes of LBBP vs LVSP vs BIVP for CRT.
In this prospective multicenter observational study, LBBP was compared with LVSP and BIVP in patients undergoing CRT. The primary composite outcome was freedom from heart failure (HF)–related hospitalization and all-cause mortality. Secondary outcomes included individual components of the primary outcome, postprocedural NYHA functional class, and electrocardiographic and echocardiographic parameters.
A total of 415 patients were included (LBBP: n = 141; LVSP: n = 31; BIVP: n = 243), with a median follow-up of 399 days (Q1-Q3: 249.5-554.8 days). Freedom from the primary composite outcomes was 76.6% in the LBBP group and 48.4% in the LVSP group (HR: 1.37; 95% CI: 1.143-1.649; P = 0.001), driven by a 31.4% absolute increase in freedom from HF-related hospitalizations (83% vs 51.6%; HR: 3.55; 95% CI: 1.856-6.791; P < 0.001) without differences in all-cause mortality. LBBP was also associated with a higher freedom from the primary composite outcome compared with BIVP (HR: 1.43; 95% CI: 1.175-1.730; P < 0.001), with no difference between LVSP and BIVP.
In patients undergoing CRT, LBBP was associated with improved outcomes compared with LVSP and BIVP, while outcomes between BIVP and LVSP are similar.
Efficacy of left bundle branch area pacing versus biventricular pacing in patients treated with cardiac resynchronization therapy: Select site – cohort study
2024, Heart Rhythm
Cardiac resynchronization therapy (CRT) is typically attempted with biventricular (BiV) pacing. One-third of patients are nonresponders. Left bundle branch area pacing (LBBAP) has been evaluated as an alternative means.
The purpose of this study was to assess the feasibility and clinical response of permanent LBBAP as an alternative to BiV pacing.
Of 479 consecutive patients referred with heart failure, 50 with BiV-CRT and 51 with LBBAP-CRT were included in this analysis after study exclusions. Quality-of-Life (QoL) assessments, echocardiographic measurements, and New York Heart Association (NYHA) class were obtained at baseline and at 6-monthly intervals.
There were no differences in baseline characteristics between groups (all P > .05). Clinical outcomes such as left ventricular ejection fraction, left ventricular end-systolic volume, QoL, and NYHA class were significantly improved for both pacing groups compared to baseline. The LBBAP-CRT group showed greater improvement in left ventricular ejection fraction at 6 months (P = .001) and 12 months (P = .021), accompanied by greater reduction in left ventricular end-systolic volume (P = .007). QRS duration < 120 ms (baseline 160.82 ± 21.35 ms vs 161.08 ± 24.48 ms) was achieved in 30% in the BiV-CRT group vs 71% in the LBBAP-CRT group (P ≤ .001). Improvement in NYHA class (P = .031) and QoL index was greater (P = .014). Reduced heart failure admissions (P = .003) and health care utilization (P < .05) and improved lead performance (P < .001) were observed in the LBBAP-CRT group.
LBBAP-CRT is feasible and effective CRT. It results into a meaningful improvement in QoL and reduction in health care utilization. This can be offered as an alternative to BiV-CRT or potentially as first-line therapy.

View all citing articles on Scopus

: Funding Sources: None.

: Disclosures: Drs Jastrzebski, Moskal, Huybrechts, and Curila have received consultant fees from Medtronic. Dr Herweg has received consultant fees from Abbott and Biotronik. Dr Sharma has received consultant fees from Abbott, Biotronik, Boston Scientific, and Medtronic. Dr Vijayaraman has received research and fellowship support as well as speaker and consultant fees from Medtronic. He has also received consultant fees from Abbott and Biotronik. The rest of the authors report no conflicts of interest.

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Late Breaking Clinical TrialsLeft bundle branch–optimized cardiac resynchronization therapy (LOT-CRT): Results from an international LBBAP collaborative study group

Background

Objective

Methods

Results

Conclusion

Graphical abstract

Introduction

Section snippets

Methods

Population

Discussion

Conclusion

Heart Rhythm

JACC Clin Electrophysiol

Heart Rhythm

J Am Coll Cardiol

Heart Rhythm

JACC Clin Electrophysiol

Heart Rhythm

A novel pacing strategy with low and stable output: pacing the left bundle branch immediately beyond the conduction block

Can J Cardiol

Left bundle branch pacing: a comprehensive review

J Cardiovasc Electrophysiol

Latency during left ventricular pacing from the lateral cardiac veins: a cause of ineffectual biventricular pacing

Pacing Clin Electrophysiol

Mortality and morbidity in cardiac resynchronization patients: impact of lead position, paced left ventricular QRS morphology and other characteristics on long-term outcome

Europace

Late Breaking Clinical Trials
Left bundle branch–optimized cardiac resynchronization therapy (LOT-CRT): Results from an international LBBAP collaborative study group