Left Bundle Branch Area Defibrillator (LBBAD): A First-in-Human Feasibility Study

Cardiac Implantable Electronic Devices in Ischemic Cardiomyopathy

This review discusses the range of device therapy for ischemic cardiomyopathy (ICM). This article will review the primary data supporting guideline indications for cardiac implantable electronic devices in patients with ICM, with a focus on primary/secondary prevention transvenous implantable cardioverter defibrillators (ICDs), cardiac resynchronization therapy, and subcutaneous/extravascular ICDs. In addition, this review discusses emerging device therapy for ICM including left bundle area pacing/defibrillation, cardiac contractility modulation and baroflex activation therapy. Device therapy for ICM continues to evolve to incorporate diverse modalities across the spectrum from prevention of sudden cardiac death to modifying cardiac remodeling and recovery.

European Society of Cardiology (ESC) clinical consensus statement on indications for conduction system pacing, with special contribution of the European Heart Rhythm Association of the ESC and endorsed by the Asia Pacific Heart Rhythm Society, the Canadian Heart Rhythm Society, the Heart Rhythm Society, and the Latin American Heart Rhythm Society

Conduction system pacing (CSP) is being increasingly adopted as a more physiological alternative to right ventricular and biventricular pacing. Since the 2021 European Society of Cardiology pacing guidelines, there has been growing evidence that this therapy is safe and effective. Furthermore, left bundle branch area pacing was not covered in these guidelines due to limited evidence at that time. This Clinical Consensus Statement provides advice on indications for CSP, taking into account the significant evolution in this domain.

Permanent Left Bundle Branch Area DF-4 Defibrillator Lead Implantation-Feasibility, Procedural Caveats, Safety, and Follow-Up

INTRODUCTION

Permanent implantation of a DF-4 implantable cardiac defibrillator (ICD) lead in the left bundle branch area (LBBA-ICD) is the next paradigm in amalgamating cardiac resynchronization therapy (CRT) and defibrillation. We systematically investigated feasibility/success rate, procedural caveats, and complications associated with a permanent DF-4 LBBA ICD implant and pertinent data at short-term follow-up.

METHODS

We prospectively attempted implantation of 7 Fr Durata (Abbott, Chicago, IL, USA) single coil DF-4 ICD lead at the LBBA using a fixed-curve non-deflectable CPS locator delivery sheath. Standard criteria defined LBBA capture. Relevant sensing/pacing, defibrillation, radiographic, and echocardiographic parameters testing were recorded at implant, discharge and 5-month follow-up.

RESULTS

We enrolled 12 consecutive cardiac device-naïve patients (median age 67.5 years, male 91.7%, median LVEF 30%, median septal thickness 9 mm, median QRS duration 140 ms, class I CRT indication 58.3%, primary prevention ICD indication 75%). Minor complications (two transeptal perforations and one micro-dislodgment) were noted in 3/12 (25%) patients. Successful permanent LBBA ICD implant with adequate sensing/pacing was achieved in 9/12 (75%) subjects. Sustained ventricular fibrillation (VF) was inducible in 7/9 patients with successful implants with effective sensing and defibrillation in all. Follow-up device-related and echocardiographic parameters were similar at discharge and 5-month follow-up.

CONCLUSION

Permanent DF-4 LBBA ICD implant is feasible and successful in 75% of patients with an indication for ICD. With dedicated toolkits, higher volumes, and an obligate learning curve, the higher-than-expected frequency (25%) of minor complications may be ameliorated. Short-term data regarding lead and selected RV parameters remained favorable.

Feasibility, safety, and short-term follow-up of defibrillator lead at left bundle branch area pacing location: A pilot study

BACKGROUND

Left bundle branch area pacing (LBBAP) has been increasingly adopted as an alternative modality to cardiac resynchronization therapy (CRT). The feasibility and safety of using an LBBAP lead to provide sensing of ventricular arrhythmia in patients receiving an implantable cardioverter-defibrillator (ICD) with CRT has been demonstrated recently.

OBJECTIVES

The purpose of our study was to analyze the feasibility, safety, and short-term follow-up of a traditional defibrillator lead at the LBBAP location.

METHODS

Patients who underwent successful LBBAP defibrillator using DF-1/DF-4 lead and delivery catheter were included in the study. Defibrillation threshold (DFT) testing was performed after implantation to assess the ability of the LBBAP defibrillator lead to sense and provide appropriate therapy for ventricular arrhythmia.

RESULTS

Although the ICD lead could be successfully deployed in the left bundle branch area in 7 of 8 patients, it was repositioned to the right ventricular (RV) apex because of atrial oversensing in 1 patient and cheesy septum in another patient. Acute procedural success was 62.5% (5/8 patients). Mean patient age was 62.6 ± 21.6 years. Mean procedural duration was 115.6 ± 38.1 minutes, with LBBAP defibrillator lead fluoroscopy duration of 10.6 ± 3.5 minutes. Mean capture threshold was 0.58 ± 0.23V/0.4 ms, sensed R-wave amplitude 9.6 ± 2.2 mV, pacing impedance 560 ± 145 Ω, and shock impedance 65.4 ± 5.5 Ω. Defibrillation testing was successful in inducing ventricular fibrillation and could be sensed and reverted promptly by the shock delivered through the lead. During mean follow-up of 3.8 ± 2.2 months, pacing parameters remained stable. No episodes of inappropriate arrhythmia detection or therapy delivery occurred during follow-up.

CONCLUSION

LBBAP defibrillator is feasible, safe, and effective during short-term follow-up. DFT testing at the time of implantation will help to ensure appropriate sensing and treatment of ventricular arrhythmias.

Standard Defibrillator Leads for Left Bundle Branch Area Pacing: First-in-Man Experience and Short-Term Follow-Up

The authors report for the first time to their knowledge, implantation of a standard implantable cardioverter-defibrillator lead for permanent delivery of left bundle branch area pacing. Implantation was successful and safe in 11 of 12 patients, with adequate defibrillation testing, good electrical and electrocardiographic parameters, and uneventful device-related short-term follow-up.

Therapeutic potential of conduction system pacing as a method for improving cardiac output during ventricular tachycardia

BACKGROUND

Ventricular tachycardia (VT) reduces cardiac output through high heart rates, loss of atrioventricular synchrony, and loss of ventricular synchrony. We studied the contribution of each mechanism and explored the potential therapeutic utility of His bundle pacing to improve cardiac output during VT.

METHODS

Study 1 aimed to improve the understanding of mechanisms of harm during VT (using pacing simulated VT). In 23 patients with left ventricular impairment, we recorded continuous ECG and beat-by-beat blood pressure measurements. We assessed the hemodynamic impact of heart rate and restoration of atrial and biventricular synchrony. Study 2 investigated novel pacing interventions during clinical VT by evaluating the hemodynamic effects of His bundle pacing at 5 bpm above the VT rate in 10 patients.

RESULTS

In Study 1, at progressively higher rates of simulated VT, systolic blood pressure declined: at rates of 125, 160, and 190 bpm, -22.2%, -42.0%, and -58.7%, respectively (ANOVA p < 0.0001). Restoring atrial synchrony alone had only a modest beneficial effect on systolic blood pressure (+ 3.6% at 160 bpm, p = 0.2117), restoring biventricular synchrony alone had a greater effect (+ 9.1% at 160 bpm, p = 0.242), and simultaneously restoring both significantly increased systolic blood pressure (+ 31.6% at 160 bpm, p = 0.0003). In Study 2, the mean rate of clinical VT was 143 ± 21 bpm. His bundle pacing increased systolic blood pressure by + 14.2% (p = 0.0023). In 6 of 10 patients, VT terminated with His bundle pacing.

CONCLUSIONS

Restoring atrial and biventricular synchrony improved hemodynamic function in simulated and clinical VT. Conduction system pacing could improve VT tolerability and treatment.

Successful direct pacing of the left bundle branch area with ICD lead using steerable delivery sheath

Recently, conduction system pacing has been performed in patients with impaired cardiac function. We report a case in which a DF4 implantable cardioverter defibrillator lead was screwed directly into the left bundle branch area with the support of a steerable delivery sheath.

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.

Feasibility of Single-lead Cardiac Resynchronization and Defibrillation Therapy in an Animal Model

Conduction system pacing (CSP) has emerged as an alternative to cardiac resynchronization therapy (CRT); however, there is limited experience with CSP using implantable cardiac defibrillator (ICD) leads. The achievement of CSP with an ICD lead may yield comparable results to cardiac resynchronization therapy defibrillator (CRT-D) therapy using fewer leads. We implanted the Biotronik Linox DX "VDD"-programmable ICD lead in a swine model to investigate the feasibility of "single-lead" CRT-D implantation. With the lead embedded in the basal right ventricular septum, morphologic criteria for CSP were achieved, and successful defibrillation was performed while maintaining atrial sensing. Future work may assure reproducibility of these findings and further determine the feasibility of a single-lead CRT-D.

Cardiac resynchronization therapy-defibrillator implantation with shock lead placement in the left bundle branch area: a case report

Background

Cardiac resynchronization therapy (CRT) with biventricular pacing is a well-established therapy. Left bundle branch area pacing (LBBAP) is a safe technique providing physiological pacing, and LBBAP-optimized CRT (LOT-CRT) has been shown to provide better electrical resynchronization than traditional CRT. However, there are few reports on shock lead placement in the left bundle branch area (LBBA) during CRT-defibrillator (CRT-D) implantation.

Case summary

A 76-year-old woman with heart failure from dilated cardiomyopathy presented with left bundle branch block pattern (QRS duration, 160 ms). Left ventricular ejection fraction was 21%. Cardiac resynchronization therapy-defibrillator implantation was performed due to worsening symptoms. By reshaping the Agilis HisPro catheter and adding a septal curve, the shock lead was placed deep into the ventricular septum, narrowing QRS duration to 114 ms. Left ventricular activation time was 84 ms. A defibrillation threshold test confirmed successful treatment without adverse events. At 6-month follow-up, left ventricular ejection fraction improved from 21 to 63%, with the patient's condition improving from New York Heart Association class III to class I.

Discussion

It was reported that QRS narrowing in CRT was related to long-term mortality, and LOT-CRT further decreased QRS duration as compared with LBBP only or biventricular pacing and increased the response rate. Combining LBBAP with coronary sinus pacing can potentially achieve superior electrical resynchronization. Lack of a suitable tool for direct shock lead placement in LBBA necessitated additional LBBAP lead in conventional LOT-CRT. Our successful LOT-CRT-D procedure with minimal number of leads through Agilis HisPro catheter reshaping enabled direct LBBA shock lead placement.

Is Conduction System Pacing a Valuable Alternative to Biventricular Pacing for Cardiac Resynchronization Therapy?

Cardiac resynchronization therapy (CRT) significantly improves clinical outcomes in patients with ventricular systolic dysfunction and dyssynchrony. Biventricular pacing (BVP) has a class IA recommendation for patients with symptomatic heart failure with reduced ejection fraction (HFrEF) and left bundle branch block (LBBB). However, approximately 30% of patients have a poor therapeutic response and do not achieve real clinical benefit. Pre-implant imaging, together with tailored programming and dedicated device algorithms, have been proposed as possible tools to improve success rate but have shown inconsistent results. Over the last few years, conduction system pacing (CSP) is becoming a real and attractive alternative to standard BVP as it can restore narrow QRS in patients with bundle branch block (BBB) by stimulating and recruiting the cardiac conduction system, thus ensuring true resynchronization. It includes His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). Preliminary data coming from small single-center experiences are very promising and have laid the basis for currently ongoing randomized controlled trials comparing CSP with BVP. The purpose of this review is to delve into the emerging role of CSP as an alternative method of achieving CRT. After framing CSP in a historical perspective, the pathophysiological rationale and available clinical evidence will be examined, and crucial technical aspects will be discussed. Finally, evidence gaps and future perspectives on CSP as a technique of choice to deliver CRT will be summarized.

Left bundle branch pacing lead for sensing ventricular arrhythmias in implantable cardioverter-defibrillator: A pilot study (LBBP-ICD study)

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Outcomes of dual-chamber implantable cardioverter defibrillator for left bundle branch area pacing: A systematic review of literature

OBJECTIVE

This systematic review of literature aimed to evaluate the safety and efficacy of dual-chamber ICDs for LBBAP in patients with left bundle branch block (LBBB).

METHODS

Digital databases were searched systematically to identify studies reporting the left bundle branch area pacing (LBBAP) with implantable cardioverter defibrillator (ICD) placement in patients with LBBB. Detailed study and patient-level baseline characteristics including the type of study, sample size, follow-up, number of cases, age, gender, and baseline characteristics were abstracted.

RESULTS

In a total of three studies, 34 patients were included in this review. There was a significant improvement reported in QRS duration in all studies. The mean QRS duration at baseline was 170 ± 17.4 ms, whereas the follow-up QRS duration at follow-up was 121 ± 17.3 ms. Two studies reported a significant improvement of 50% in LVEF from baseline. No lead-related complications or arrhythmic events were recorded in any study. The findings of the systematic review suggest that dual-chamber ICD for LBBAP is a promising intervention for patients with heart conditions.

CONCLUSION

The procedure offers significant improvements in QRS duration and LVEF, and there were no lead-related complications or arrhythmic events recorded in any of the studies.

The Emerging Role of Left Bundle Branch Area Pacing for Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) reduces the risk of heart failure-related hospitalisations and all-cause mortality, as well as improving quality of life and functional status in patients with persistent heart failure symptoms despite optimal medical treatment and left bundle branch block. CRT has traditionally been delivered by implanting a lead through the coronary sinus to capture the left ventricular epicardium; however, this approach is associated with significant drawbacks, including a high rate of procedural failure, phrenic nerve stimulation, high pacing thresholds and lead dislodgement. Moreover, a significant proportion of patients fail to derive any significant benefit. Left bundle branch area pacing (LBBAP) has recently emerged as a suitable alternative to traditional CRT. By stimulating the cardiac conduction system physiologically, LBBAP can result in a more homogeneous left ventricular contraction and relaxation, thus having the potential to improve outcomes compared with conventional CRT strategies. In this article, the evidence supporting the use of LBBAP in patients with heart failure is reviewed.

A Novel Technique of Placing Desfibrillator Leads in Patients with Persistent Left Superior Vena Cava

Persistent left superior vena cava is the most common thoracic venous anomaly. It is usually asymptomatic, but it can make implanting intracardiac devices difficult.We present a novel technique to facilitate desfibrillator lead implantation in patients with persistent left superior vena cava and the absence of the right superior vena cava. We used a fixed-curve Selectra 3D 65-42 cm sheath (Biotronik), orienting it toward the tricuspid valve (TV) by rotating it counter-clockwise. During follow-up, the electrodes remained stable.Our technique was safe, simple, and feasible for patients with this complex venous anatomy.