Simplifying Physiological Left Bundle Branch Area Pacing Using a New Nine-Partition Method

Safety assessment of coronary arteries during left bundle branch area pacing

BACKGROUND

This study aimed to assess the safety of left bundle branch area pacing (LBBAP) by measuring the distance from the tip of the electrode to the nearby coronary artery with a nine-partition grid method.

METHODS

From January 2019 to October 2020, patients who underwent LBBAP and postoperative coronary angiography in the Second Affiliated Hospital of Nanchang University were included in the study. The patients' fluoroscopic images of LBBAP and coronary angiography were collected and analyzed. Changes in the ST‑T segment in the electrocardiogram (ECG), serum troponin, and myocardial enzyme profiles were observed before and after the LBBAP procedure.

RESULTS

A total of 50 patients were included in this study, of whom 46 patients underwent implantation with a pacemaker and 4 patients received an implantable cardioverter defibrillator (ICD). The pacing electrodes were confined to the posterior-middle (PM), median (M), Posterior inferior (PI), and middle inferior (MI) positions of the two-dimensional nine-square grid or in the junction area of the above positions, and were concentrated in the rectangle formed by the line of the center points of the four positions. The average vertical distances from the electrode tip to the left anterior descending branch artery (LAD), posterior descending branches (PD) and the left posterior ventricular branches (PL) were 19.69 ± 8.72 mm, 26.09 ± 8.02 mm, and 21.11 ± 7.86 mm, respectively; the minimum was 5.28 mm, 9.51 mm, and 8.69 mm, respectively. Coronary angiography in all patients showed no significant injury to the ventricular septal branch; however, we observed elevated serum troponin and changes in ST‑T segment in ECG.

CONCLUSION

The study demonstrates that pacing electrodes in LBBAP can be safely implanted over a wide range. Coronary arteries are likely to be safe when the pacing electrodes are located within the rectangle formed by the line connecting the PM, M, PI, and MI zone centroids. The left bundle branch can be quickly captured and the safety of the coronary artery can be improved by locating the electrode in the posterior-mid zone. The potential risk of injury to the LAD from the electrode is greater compared with the PD.

Sex Differences in Left Bundle Branch Area Pacing Versus Biventricular Pacing for Cardiac Resynchronization Therapy

BACKGROUND

Women respond more favorably to biventricular pacing (BIVP) than men. Sex differences in atrioventricular and interventricular conduction have been described in BIVP studies. Left bundle branch area pacing (LBBAP) offers advantages due to direct capture of the conduction system. We hypothesized that men could respond better to LBBAP than BIVP.

OBJECTIVES

This study aims to describe the sex differences in response to LBBAP vs BIVP as the initial cardiac resynchronization therapy (CRT).

METHODS

In this multicenter prospective registry, we included patients with left ventricular ejection fraction ≤35% and left bundle branch block or a left ventricular ejection fraction ≤40% with an expected right ventricular pacing exceeding 40% undergoing initial CRT with LBBAP or BIVP. The composite primary outcome was heart failure-related hospitalization and all-cause mortality. The primary safety outcome included all procedure-related complications.

RESULTS

There was no significant difference in the primary outcome when comparing men and women receiving LBBAP (P = 0.46), whereas the primary outcome was less frequent in women in the BIVP group than men treated with BIVP (P = 0.03). The primary outcome occurred less frequently in men undergoing LBBAP (29.9%) compared to those treated with BIVP (46.5%) (P = 0.004). In women, the incidence of the primary endpoint was 24.14% in the LBBAP group and 36.2% in the BIVP group; however, this difference was not statistically significant (P = 0.23). Complication rates remained consistent across all groups.

CONCLUSIONS

Men and women undergoing LBBAP for CRT had similar clinical outcomes. Men undergoing LBBAP showed a lower risk of heart failure-related hospitalizations and all-cause mortality compared to men undergoing BIVP, whereas there was no difference between LBBAP and BIVP in women.

Comparison of clinical outcomes between transthoracic echocardiography- and X-ray-guided left bundle branch pacing for bradycardia: A randomized controlled trial

INTRODUCTION

Left bundle branch pacing (LBBP) is a physiological pacing modality. However, the long procedure and fluoroscopy time of LBBP is still a problem. This study aims to compare the clinical outcomes between transthoracic echocardiography (TTE)- and X-ray-guided LBBP.

METHODS

This is a single-center, prospective, randomized controlled study. Consecutive patients who underwent LBBP in our team from June 2022 to November 2022 were enrolled. Procedure and fluoroscopy time, pacing parameters, electrophysiological and echocardiographic characteristics, as well as complications were recorded at implantation and during follow-up.

RESULTS

In this study, 60 patients were enrolled and divided into two groups: 30 patients were allocated to the X-ray group and the remaining 30 to the TTE group. There was no significant difference in the success rate between the two groups (86.7% vs. 76.7%, p = .317). The procedure time of TTE group was comparable to that of the X-ray group (9.0 vs. 12.0 min, p = .063). However, the fluoroscopy time in the TTE group was significantly lower than that of the X-ray group (2.5 vs. 5.0 min, p = .002). There were no statistically significant differences in pacing parameters, electrophysiological and echocardiographic characteristics, or complications between the two groups at implantation and during follow-up.

CONCLUSION

TTE-guided LBBP is a feasible and safe method. Compared with X-ray, TTE showed a comparable success rate and procedure time, but it could significantly reduce the fluoroscopy time of LBBP.

An individualized criterion for left bundle branch capture in patients with a narrow QRS complex

BACKGROUND

Left bundle branch (LBB) pacing (LBBP) is a physiological pacing; however, the accuracy of current electrocardiographic criteria for LBBP remains inadequate.

OBJECTIVE

The purpose of this study was to establish a novel individualized criterion to improve the accuracy of LBBP determination in patients with a narrow QRS complex.

METHODS

Patients in whom both LBBP and left ventricular septal pacing (LVSP) were acquired during operation were enrolled. LBB conduction time (LBBCT) was measured from LBB potential (LBBpo) to intrinsic QRS onset. LBBpo-V6RWPT, Native-V6RWPT, and Paced-V6RWPT were respectively measured from LBBpo, intrinsic QRS onset, and stimulus to R-wave peak in V6. ΔV6RWPT was the difference value between Paced-V6RWPT and Native-V6RWPT. The accuracy of ΔV6RWPT criterion for determining LBBP was evaluated.

RESULTS

In all 71 enrolled patients, ΔV6RWPT was <30 ms during LBBP (21.3 ± 4.6 ms; range 9.3-28.3 ms) but was >30 ms during LVSP (38.5 ± 4.6 ms; range 31.1-47.0 ms). The probability distribution of ΔV6RWPT was well separated between LBBP and LVSP. Sensitivity and specificity of the novel criterion of "ΔV6RWPT <30 ms" for determining LBBP both were 100%. However, the optimal cutoff value of Paced-V6RWPT for validation of LBBP was 64.2 ms, and sensitivity and specificity were 84.5% and 97.2%, respectively. Paced-V6RWPT during LBBP was equivalent to LBBpo-V6RWPT in all patients. There was a strong linear correlation between Native-V6RWPT and LBBpo-V6RWPT (r = 0.796; P <.001).

CONCLUSION

ΔV6RWPT could be an accurate individualized criterion for determining LBB capture with high sensitivity and specificity and was superior over the fixed Paced-V6RWPT criterion.

Left Bundle Branch Pacing vs Left Ventricular Septal Pacing vs Biventricular Pacing for Cardiac Resynchronization Therapy

BACKGROUND

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.

OBJECTIVES

The purpose of this study was to compare the outcomes of LBBP vs LVSP vs BIVP for CRT.

METHODS

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.

RESULTS

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.

CONCLUSIONS

In patients undergoing CRT, LBBP was associated with improved outcomes compared with LVSP and BIVP, while outcomes between BIVP and LVSP are similar.

Feasibility and safety of left bundle branch area pacing in cardiac amyloidosis. A single center experience

BACKGROUND

Conventional right ventricle (RV) pacemaker stimulation has been associated with worse clinical outcomes in patients with cardiac amyloidosis (CA). Left bundle branch area pacing (LABPP) has been suggested as a promising alternative. We sought to assess the safety, feasibility, and outcomes of LABPP in patients with CA.

METHODS

We retrospectively analyzed echocardiography and pacing parameters and clinical outcomes in 23 consecutive patients with CA and LBBAP implanted from June 2020 to October 2022.

RESULTS

LBBAP was successfully performed in 22 over 23 patients (19 male, 78.6 ± 11.7 years, 20 ATTR, mean LVEF 45.5 ± 16.2%). After the procedure, 9 patients showed Qr pattern and 11 a qR pattern in V1 on ECG. Average procedure time was 67 ± 28 min. After 7.7 ± 5.2 months follow-up, no procedure-related complications had occurred. Although, a significant reduction in QRS width (p = .001) was achieved, we did not observe significant changes in LVEF and Nt ProBNP at 6 months of follow-up. Pacing parameters were stable during follow-up: LBB capture threshold and R wave amplitude were 1.0 ±  0.5 V and 10.6 ± 6.0 mV versus 0.8 ±  0.1 V, p = .21 and 10.6 ± 5.1 mV (p = .985) at follow up.

CONCLUSION

LBBAP is safe and feasible pacing technique for patients with CA. LBBAP is associated with significant narrowing of QRSd without worsening in LVEF and Nt-proBNP.

Coronary artery complications after left bundle branch area pacing: An increasingly reported issue in the era of physiologic pacing

Coronary artery lesions related to pacemaker implantation are rare complications. With the increasing adoption of the technique of permanent transseptal pacing of the left bundle branch area pacing (LBBAP), an increase in the incidence of these complications may be expected. We report two cases of coronary lesions after permanent transeptal pacing of the LBBAP: the first with a small coronary artery fistula, and the second with an extrinsic coronary compression. Both complications occurred with stylet-driven pacing leads with extendable helix. In the first case, since the shunt volume was small and no major complications were reported, the patient was treated conservatively with good outcome. The second case required lead repositioning due to acute decompensated heart failure.

Clinical outcomes of left bundle branch area pacing: Prognosis and specific applications

Cardiac pacing has become a widely accepted treatment strategy for bradyarrhythmia and heart failure. However, conventional right ventricular pacing (RVP) has been associated with electrical dyssynchrony, which may result in atrial fibrillation and heart failure. To achieve physiological pacing, Deshmukh et al. reported the first case of His bundle pacing (HBP) in 2000. This strategy was reported to have preserved ventricular synchronization by activating the conventional conduction system. Nonetheless, due to the anatomical location of the His bundle (HB), several issues such as high pacing thresholds, lead fixation, and early battery depletion may pose a challenge. Recently, left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing strategy to achieve conduction system pacing by capturing the left bundle branch through the deep septum. Additionally, several studies have investigated the clinical outcomes of LBBAP. In this paper, we describe the pacing parameters, QRS duration (QRSd), cardiac function, complications, and specific applications of LBBAP in recent years.

Transvenous left bundle branch pacing during cardiac surgery: A case report

Left bundle branch pacing (LBBP) was a promising physiological pacing method, which could prevent or treat heart failure. We reported a young woman with severe valvular disease and heart failure receiving LBBP under direct vision and without x-ray assistance during cardiac surgery. To the best of our knowledge, this was the first case report of this type of pace maker implantation.

Practical and systematic approach using the steerable catheter and stylet-driven lead to deliver safe and effective left bundle branch area pacing

INTRODUCTION

Current delivery tools were not designed for left bundle branch area pacing (LBBAP). Challenges using these tools include lack of reach into the right ventricle and poor support for the lead to penetrate the interventricular septum. Concerns using stylet-driven leads (SDL) for LBBAP have been previously highlighted. Knowledge and the technical know-how of using SDL for LBBAP need to be evaluated in a fair and consistent manner. A stepwise approach is devised for use of Agilis HisProTM steerable catheter with Tendril STS Model 2088TC lead for LBBAP and evaluated for safety and reproducibility.

METHODS

Consecutive patients undergoing LBBAP using the stepwise approach with Agilis HisProTM steerable catheter were analyzed. The safety, efficacy and reproducibility of the technique were evaluated. The lead parameters were analyzed in the immediate (1 day) and short-term period (3-6 months) post implantation.

RESULTS

LBBAP was attempted in 41 patients using the stepwise approach of which 37 (90.7%) were successful. The lead parameters were stable in the immediate and short-term post implantation in all our patients. There was no significant difference between the group of patients with multiple repositioning of the lead compared to those successful at the 1st attempt. There were no acute or short-term lead and procedural complications.

CONCLUSION

A stepwise and systematic approach using the Agilis HisProTM steerable catheter and proper handling of the Tendril STS Model 2088TC stylet-driven lead is an important part of the armamentarium to deliver LBBAP in a practical, effective and reproducible manner.

Left Bundle Branch Area Pacing Versus Biventricular Pacing as Initial Strategy for Cardiac Resynchronization

BACKGROUND

Left bundle branch area pacing (LBBAP) for cardiac resynchronization therapy (CRT) is an alternative to biventricular pacing (BiVp).

OBJECTIVES

The purpose of this study was to compare the outcomes between LBBAP and BiVp as an initial implant strategy for CRT.

METHODS

In this prospective multicenter, observational, nonrandomized study, first-time CRT implant recipients with LBBAP or BiVp were included. The primary efficacy outcome was a composite of heart failure (HF)-related hospitalization and all-cause mortality. The primary safety outcomes were acute and long-term complications. Secondary outcomes included postprocedural New York Heart Association functional class and electrocardiographic and echocardiographic parameters.

RESULTS

A total of 371 patients (median follow-up of 340 days [IQR: 206-477 days]) were included. The primary efficacy outcome occurred in 24.2% in the LBBAP vs 42.4% in the BiVp (HR: 0.621 [95% CI: 0.415-0.93]; P = 0.021) group, driven by a reduction in HF-related hospitalizations (22.6% vs 39.5%; HR: 0.607 [95% CI: 0.397-0.927]; P = 0.021) without significant difference in all-cause mortality (5.5% vs 11.9%; P = 0.19) or differences in long-term complications (LBBAP: 9.4% vs BiVp: 15.2%; P = 0.146). LBBAP resulted in shorter procedural (95 minutes [IQR: 65-120 minutes] vs 129 minutes [IQR: 103-162 minutes]; P < 0.001) and fluoroscopy times (12 minutes [IQR: 7.4-21.1 minutes] vs 21.7 minutes [IQR: 14.3-30 minutes]; P < 0.001), shorter QRS duration (123.7 ± 18 milliseconds vs 149.3 ± 29.1 milliseconds; P < 0.001), and higher postprocedural left ventricular ejection fraction (34.1% ± 12.5% vs 31.4% ± 10.8%; P = 0.041).

CONCLUSIONS

LBBAP as an initial CRT strategy resulted in a lower risk of HF-related hospitalizations compared to BiVp. A reduction in procedural and fluoroscopy times, shorter paced QRS duration, and improvements in left ventricular ejection fraction compared with BiVp were observed.

Quantitative analysis reveals influencing factors to facilitate successful anodal-ring capture in left bundle branch pacing

AIMS

Left bundle branch pacing (LBBP) maintains left ventricular synchrony but induces right ventricular conduction delay (RVCD). Although anodal-ring capture (ARC) during bipolar LBBP improves RVCD, it is not achieved in all patients receiving LBBP. This study aimed to analyze the factors influencing ARC implementation.

METHODS AND RESULTS

Patients receiving LBBP with intraoperative ARC testing were enrolled. Electrocardiographic parameters were measured, including stimulus-to-QRS duration (stim-QRSd), stimulus-to-left/right ventricular activation time (stim-LVAT/RVAT), and V6-V1 interpeak interval. The distribution of lead-tip sites was described as the corrected longitudinal and lateral distance (longit-/lat-dist). Relative angles of the LBBP lead were measured. Echocardiography in short-axis view was used to measure the intraseptal lead length. Intergroup comparisons, correlation analysis, and stepwise logistic regression were performed. In total, 105 patients were included, among which 65 (62%) patients achieved ARC at a pacing output ≤ 5.0 V/0.5 ms (average 3.1 V/0.5 ms). Anodal-ring capture further shortened the stim-QRSd by 13.1 ± 7.5 ms. Better unipolar-ring (cathodal) threshold and R-wave sensing in LBBP-ARC group indicated the critical role of ring-septum contact in ARC. Longer corrected longit-dist and shorter corrected lat-dist of lead-tip sites were positively correlated with higher success likelihood of ARC, likely due to the greater relative angle in which the lead enters the septum and consequently the longer intraseptal lead length and better ring-septum contact.

CONCLUSION

This study elucidated the factors affecting the success likelihood of LBBP-ARC. These findings improve the understanding of LBBP-ARC, providing references for future research and clinical practice.

A novel approach for developing left bundle branch pacing and left bundle branch block in a canine model

BACKGROUND AND OBJECTIVE

Left bundle branch pacing (LBBP) has shown the benefits in the treatment of dyssynchronous heart failure (HF). The purpose of this study was to develop a novel approach for LBBP and left bundle branch block (LBBB) in a canine model.

METHODS

A "triangle-center" method by tricuspid valve annulus angiography for LBBP implantation was performed in 6 canines. A catheter was then applied for retrograde His potential recording and left bundle branch (LBB) ablation simultaneously. The conduction system was stained to verify the "triangle-center" method for LBBP and assess the locations of the LBB ablation site in relation to the left septal fascicle (LSF).

RESULTS

The mean LBB potential to ventricular interval and stimulus-peak left ventricular activation time were 11.8 ± 1.2 and 35.7 ± 3.1 ms, respectively. The average intrinsic QRS duration was 44.7 ± 4.7 ms. LBB ablation significantly prolonged the QRS duration (106.3 ± 8.3 ms, p < .001) while LBBP significantly shortened the LBBB-QRS duration to 62.5 ± 5.3 ms (p < .001). After 6 weeks of follow-up, both paced QRS duration (63.0 ± 5.4 ms; p = .203) and LBBB-QRS duration (107.3 ± 7.4 ms; p = .144) were unchanged when comparing to the acute phase, respectively. Anatomical analysis of 6 canine hearts showed that the LBBP lead-tip was all placed in LSF area.

CONCLUSION

The new approach for LBBP and LBBB canine model was stable and feasible to simulate the clinical dyssynchrony and resynchronization. It provided a useful tool to investigate the basic mechanisms of underlying physiological pacing benefits.

Left bundle branch pacing on mechanical synchrony and myocardial work in bradycardia patients

Left bundle branch pacing (LBBP) has emerged as a novel physiological pacing method to produce narrower QRS duration, but whether it could restore mechanical synchrony and improve myocardial work still lacks sufficient evidence. Therefore, the goal of this study was to evaluate mechanical synchrony and myocardial work in LBBP. We collected 20 patients with LBBP due to symptomatic bradycardia and another 29 age-matched patients with right ventricular pacing (RVP). For LBBP patients, cardiac electro-mechanical synchrony and myocardial work were measured at baseline and 7 days after implantation and compared with the RVP patients. In the LBBP group, paced QRS duration and mechanical synchrony were not significantly different from baseline(all P > 0.05), but significantly smaller than that in the RVP group (all P<0.05). Meanwhile, global longitudinal strain (GLS) in LBBP was greater than that in the RVP group (17.7 ± 3.5% vs. 14.8 ± 3.1%, P < 0.05). Global myocardial work index and global constructive work were also better than that in the RVP group(all P<0.05). Global work efficiency was 91.9 ± 3.1%, which was greater when compared with RVP (P < 0.05). LBBP provides better cardiac electro-mechanical synchrony and more effective myocardial work than that in RVP, thus improving global heart function.

Assessment of Cardiac Function and Ventricular Mechanical Synchronization in Left Bundle Branch Area Pacing by Speckle Tracking and Three-Dimensional Echocardiography

Real-time 3-dimensional echocardiography combined with speckle tracking was used in this study. A total of 90 patients with normal left ventricular ejection fraction were divided into 3 groups according to the pacing site: left bundle branch area pacing (LBBAP), right ventricular septal pacing (RVSP) or right ventricular apical pacing (RVAP). Procedure duration (90 ± 18 vs 61 ± 6.6 vs 58 ± 5.6 minutes, p = 0.015), Fluoroscopy duration (15.5 ± 5.4 vs 4.8 ± 2.2 vs 4 ± 1.9 minutes, p = 0.004), and ventricular capture threshold at implantation (0.8 ± 0.3 vs 0.6 ± 0.2 vs 0.6 ± 0.1 V, p = 0.002) were significantly increased in patients that received LBBAP compared with RVSP or RVAP. At 4 weeks of follow-up, brain natriuretic peptide levels were significantly lower (22 [12 to 59] vs 135 [86 to 231] vs 235 [147 to 428] pg/ml, p = 0.04), paced QRS duration was significantly shorter (115 ± 26 vs 134 ± 28 vs 157 ± 29 ms, p = 0.012), and global longitudinal strain (-19.4 ± 2.4 vs -19.3 ± 3.4 vs -17.3 ± 3.5%, p = 0.026) and systolic dyssynchrony index (2.5 ± 0.3 vs 5.9 ± 0.9 vs 7.7 ± 1.2, p = 0.001), longitudinal absolute maximum difference of time to peak strain (17 [6 to 68] vs 117 [71 to 173] vs 126 [79 to 178] ms, p <0.0001), and circumferential absolute maximum difference of time to peak strain (76 [32 to 129] vs 148 [117 to 208] vs 161 [118 to 266] ms, p = 0.005) were significantly lower in patients that received LBBAP compared with RVSP or RVAP. In conclusion, LBBAP can provide a more physiological ventricular activation pattern than RVSP or RVAP and results in good left ventricular electrical and mechanical synchronization.

Success rates, challenges and troubleshooting of left bundle branch area pacing as a cardiac resynchronization therapy for treating patients with heart failure

Cardiac resynchronization therapy (CRT) is an important treatment of heart failure patients with reduced left ventricular ejection fraction (LVEF) and asynchrony of cardiac electromechanical activity. Left bundle branch area pacing (LBBaP) is a novel physiological pacing modality that appears to be an effective method for CRT. LBBaP has several advantages over the traditional biventricular-CRT (BiV-CRT), including a low and stable pacing capture threshold, a high success rate of implantation, a short learning curve, and high economic feasibility. However, LBBaP is not suitable for all heart failure patients needing a CRT and the success rates of LBBaP in heart failure patients is lower because of myocardial fibrosis, non-specific intraventricular conduction disturbance (IVCD), enlargement of the right atrium or right ventricle, etc. In this literature review, we summarize the success rates, challenges, and troubleshooting of LBBaP in heart failure patients needing a CRT.

A Continuous Pacing and Recording Technique for Differentiating Left Bundle Branch Pacing From Left Ventricular Septal Pacing: Electrophysiologic Evidence From an Intrapatient-Controlled Study

BACKGROUND

Left bundle branch pacing (LBBP) is a promising approach for achieving near-physiologic pacing. However, differentiating LBBP from left ventricular septal endocardial pacing (LVS(e)P) remains a challenge. This study aimed to establish a simple and effective method for differentiating LBBP from LVS(e)P and to evaluate their electrophysiologic characteristics.

METHODS

LBBP, using continuous uninterrupted pacing and real-time monitoring of electrocardiograms along with intracardiac electrograms, was performed in 97 consecutive patients. We evaluated the electrophysiologic characteristics observed during LBBP using 6 modalities: right ventricular septal pacing (RVSP), intraventricular septal pacing (IVSP 1 and 2), LVS(e)P, nonselective LBBP (NSLBBP), and selective LBBP (SLBBP).

RESULTS

Of the 97 patients, 87 (89.7%) met the criteria (abrupt change in paced QRS morphology with a transition from Qr to QR/qR in lead V1 and shortening of stimulus to V6 R-wave peak time [Stim-V6RWPT] of ≥ 10 ms with constant output while rather than after lead screwing) for nonselective left bundle branch (LBB) capture. Selective LBB capture was observed in 82 patients (84.5%). The Stim-V6RWPT of NSLBBP and SLBBP were significantly shorter than LVS(e)P (respectively, 67.1 ± 8.7 ms, 67.0 ± 9.3 ms, and 82.1 ± 10.9 ms). Stim-QRSend was the narrowest in IVSP2 (136.6 ± 15.2 ms) instead of NSLBBP (140.0 ± 17.1 ms).

CONCLUSIONS

The uninterrupted pacing technique for differentiating LBBP from LVS(e)P in the same group of patients is feasible. Electrophysiologic evidence from our intrapatient-controlled study shows that LBBP and LVS(e)P differ in ventricular electrical synchronization.

His-Purkinje system pacing reduced tricuspid regurgitation in patients with persistent atrial fibrillation after left-sided valve surgery

Background & objective

Tricuspid regurgitation after left-sided valve surgery was a common and difficult problem. Atrial fibrillation was considered to be an important etiology of tricuspid regurgitation. His-Purkinje system pacing (HPSP) was a physiological pacing method, which could prevent and treat heart failure and might reduce tricuspid regurgitation. Our study aimed to investigate the effect of HPSP on tricuspid regurgitation in patients with persistent atrial fibrillation after left-sided valve surgery.

Methods

This study was a retrospective study. The 3-year patient review focused on those who underwent permanent cardiac pacemaker implantation of HPSP after mitral valve and/or aortic valve replacement from Jan 1st, 2019 to Jan 1st, 2022. HPSP included His bundle pacing (HBP) or left bundle branch pacing (LBBP). Clinical data collected included electrocardiogram, pacing parameters, ultrasonic cardiogram parameters and chest x-ray at implantation and 3-month follow up. Univariate and multivariate linear regression analysis of tricuspid regurgitation velocity were performed.

Results

A total of 44 patients was retrospectively reviewed. Eight patients who had undergone implantation of HPSP after left-sided heart valve replacement were enrolled in the study. All patients had persistent atrial fibrillation. Three of them received HBP and five underwent LBBP. At 3-month follow-up, the tricuspid regurgitation grade was significantly lower than that before implantation (P = 0.007). The tricuspid regurgitation velocity significantly decreased (317 ± 74 cm/s vs. 261 ± 52 cm/s, P = 0.022) and tricuspid valve pressure gradient (PG) reduced (42 ± 21 mmHg vs. 28 ± 10 mmHg, P = 0.040). The cardiothoracic ratio of patients was significantly lower than that before implantation (0.61 ± 0.08 vs. 0.64 ± 0.09, P = 0.017). The NYHA classification of patients also improved (P = 0.013). In multivariate liner regression analysis, the pacing ratio (β = 0.736, P = 0.037) was an independent determinant of tricuspid regurgitation velocity variation.

Conclusion

HPSP might reduce tricuspid regurgitation and improve cardiac function in patients with persistent atrial fibrillation after left-sided valve surgery.

Impact on right ventricular performance in patients undergoing permanent pacemaker implantation: Left bundle branch pacing versus right ventricular septum pacing

BACKGROUND

The novel method of left bundle branch pacing (LBBP) has been reported to achieve better electrical and mechanical synchrony in the left ventricle than conventional right ventricular pacing (RVP). However, its effects on right ventricle (RV) performance are still unknown.

METHODS

Consecutive patients undergoing dual-chamber pacemaker (PM) implantation for sick sinus syndrome (SSS) with normal cardiac function and a narrow QRS complex were recruited for the study. The pacing characteristics and echocardiogram parameters were measured to evaluate RV function, interventricular and RV synchrony, and were compared between ventricular pacing-on and native-conduction modes.

RESULTS

A total of 84 patients diagnosed with SSS and an indication for pacing therapy were enrolled. Forty-two patients (50%; mean age 65.50 ± 9.30 years; 35% male) underwent successful LBBP and 42 patients (50%; mean age 69.26 ± 10.08 years; 33% male) RVSP, respectively. Baseline characteristics were similar between the two groups. We found no significant differences in RV function [RV-FAC (Fractional Area Change)%, 47.13 ± 5.69 versus 48.60 ± 5.83, p = .069; Endo-GLS (Global Longitudinal Strain)%, -28.88 ± 4.94 versus -29.82 ± 5.35, p = .114; Myo-GLS%, -25.72 ± 4.75 versus -25.72 ± 5.21, p = .559; Free Wall St%, 27.40 ± 8.03 versus -28.71 ± 7.34, p = .304] between the native-conduction and LBBP capture modes, while the RVSP capture mode was associated with a significant reduction in the above parameters compared with the native-conduction mode (p < .0001). The interventricular synchrony in the LBBP group was also superior to the RVSP group significantly.

CONCLUSION

LBBP is a pacing technique that seems to associate with a positive and protective impact on RV performance.

Advances of Implantation Techniques for Conduction System Pacing

Conduction system pacing (CSP), including His bundle and left bundle branch pacing are physiological pacing modalities, but lead deployment is often difficult mainly due to a lack of anatomical landmark for lead tip location. Several implantation techniques for CSP implantation have been developed including 3-dimensional electroanatomical mapping, placing a second lead as a reference (dual-lead method technique), and using fluoroscopic imaging (9-partition and visualization techniques). In this review, the authors summarize the implantation techniques for CSP and compare the different methods.

Right ventriculography improves the accuracy of leadless pacemaker implantation in right ventricular mid-septum

Background

Implanting leadless pacemakers in the right ventricular (RV) apex is prone to causing pericardial tamponade and myocardial perforation.

Objective

To investigate the feasibility and safety of right ventriculography-guided implantation of Micra™ leadless pacemaker (Micra™, Medtronic, Minneapolis, MN, USA) in the RV mid-septum.

Methods

One hundred eight consecutive patients who underwent Micra™ implantation intended in the mid-septum were enrolled and randomized (3:1) into the radiography group (n = 81) with assistance of right ventriculography to illustrate the RV septum and the non-radiography group (n = 27). All subjects underwent a postoperative computed tomography (CT) scan to determine the Micra™ location. The Micra™ location assessed by CT image was compared between the two groups to confirm the accuracy of the intended pacing site. The duration of the procedure, X-ray radiation dose, and time were also compared between the two groups.

Results

Reconstructed CT 3-D cardiac images found the Micra™ location in the intended mid-septum in 13 patients (48.1%, 13/27) in the non-radiography group and 76 patients (93.8%, 76/81) in the radiography group (P < 0.0001 between two groups). There was no significant difference in procedure interval between the two groups while the X-ray radiation dose (564.86 ± 112.44 vs. 825.85 ± 156.12 mGy, P < 0.0001), X-ray exposure time (7.79 ± 1.43 vs. 12.03 ± 2.86 min, P < 0.0001), and the number of fluoroscopy re-positioning (2.79 ± 1.03 vs. 6.41 ± 1.82, P < 0.0001) were significantly less in the radiography group than in the non-radiography group. No implantation-related complications were observed in both groups.

Conclusion

Right ventriculography increases the accuracy of Micra™ implantation in the mid-septum and reduces X-ray exposure.

Trial registration

The trial registration number (ChiCTR2100051374) and date (09/22/2021).

The Initial Experience of Left Bundle Branch Area Pacing in Patients with Hypertrophic Cardiomyopathy

PURPOSE

Whether Left bundle branch area pacing (LBBAP) could be achieved in patients with hypertrophic cardiomyopathy (HCM) requiring ventricular pacing remains unknown. The present study aimed to investigate the feasibility and effect of LBBAP in HCM.

METHODS

Patients with HCM who underwent LBBAP were recruited from November 2018 to September 2021. Clinical characteristics, echocardiographic, and pacing parameters were prospectively collected at baseline and during follow-up.

RESULTS

Eleven consecutive HCM patients who attempted LBBAP were included (mean age 64.0±8.7 years, female 45.5%, mean interventricular septum 16.7mm). The success rate of LBBAP was 36.4% (4/11) and the reason for failed LBBAP in other 7 HCM patients was the inability to screw the lead into the deep septum or capture the left bundle branch. Patients with successful LBBAP had significantly narrower QRS duration than those with failed (118.0 ± 3.7 ms vs. 140.9 ± 9.4 ms, p = 0.01) while the capture thresholds, sensing amplitudes, and pacing impedances were similar. Successful cases presented with less positive late gadolinium enhancement (25.0% vs. 71.4%, p = 0.02) and thinner interventricular thickness (14.5 ± 1.0 mm vs. 18.0 ± 2.5 mm, p = 0.02) when compared with failed cases. Pacing parameters remained stable and no procedure-related complications occurred during a mean follow-up of 8.9 ± 7.3 months.

CONCLUSION

LBBAP may be successfully achieved in less than half of HCM patients due to thick interventricular septum and heavy burden of myocardial fibrosis. Pacing strategies should be cautiously considered in patients with HCM. This article is protected by copyright. All rights reserved.

Left Bundle Branch Pacing: How I Do It?

Search for the combined use of LV lead with HBP yielded 2 clinical outcome case studies and one mechanistic study in peer-reviewed journals. One case series reported implantation and follow-up of outcomes in patients who had an inadequate response to HBP with subsequent additional LV lead. Search for the combined use of LV lead with LBBAP yielded two case series studies in non-peer reviewed publications were found. The His-Optimized CRT (HOT-CRT) is a term introduced describing combining HBP with LV pacing. The LB-Optimized CRT (LOT-CRT) is a term recently used to describe combining LBBAP with LV pacing.

Preliminary study on left bundle branch area pacing in children:clinical observation of 12 cases

OBJECTIVE

To explore the safety and feasibility of left bundle branch area pacing (LBBAP) in children.

METHODS

This study observed 12 children attempted LBBAP from January 2019 to January 2021 in the department of pediatric cardiology of Anzhen Hospital prospectively.Clinical data, pacing parameters, electrocardiograms, intracardiac electrograms, echocardiographic measurements and complications were recorded at implant and during follow-up.

RESULTS

The 12 patients aged between 3 and 14 years old and weighted from 13 to 48kg. Eleven patients were diagnosed with third-degree atrioventricular block and 1 patient (case 4) suffered from cardiac dysfunction due to right ventricular apical pacing (RVAP). Left bundle branch area pacing was successfully achieved in all patients with narrow QRS complexes and V₁ lead showed changes like right bundle branch block in the pacing electrocardiogram. Left ventricular ejection fraction in case 4 recovered on the 3rd day after LBBAP. The median of left ventricular end diastolic diameter Z score of the 12 patients decreased from 1.75 to1.05 3 months after implantation (p<0.05). The median of paced QRS duration was 103ms. The median of pacing threshold, R-wave amplitude and impedance were 0.85V, 15mV and 717Ω respectively and remained stable during follow-up. No complications such as loss of capture, lead dislodgement or septal perforation occurred.

CONCLUSIONS

Left bundle branch area pacing can be performed safely in children with narrow QRS duration and stable pacing parameters. Cardiac dysfunction caused by long-term RVAP can be corrected by LBBAP quickly. This article is protected by copyright. All rights reserved.

Preliminary experience of permanent left bundle branch area pacing using stylet-directed pacing lead without delivery sheath

BACKGROUND

Left bundle branch area pacing (LBBAP) aims to capture the cardiac conduction system in area of the left bundle branch. Currently, LBBAP is mainly performed using lumen-less pacing leads (LLLs) with pre-shaped sheath. However, the data on LBBAP with stylet-driven leads (SDLs) without sheath is limited.

OBJECTIVE

This study presents the feasibility, safety, and pacing characteristics of LBBAP using stylet-driven leads (SDLs) without the support of sheath.

METHODS

A total of 25 patients with bradycardia indications who received LBBAP implantation with an attempt of SDL (FINELINE II 4471 lead, Boston Scientific, MA, US) between August 2020 and April 2021 at Sir Run Run Shaw Hospital were included in this retrospective cohort study. Twenty of them finally were paced with SDL in priority (SDL-LBBAP group). Twenty propensity score matching patients who underwent LBBAP with LLL (Select Secure 3830 lead, Medtronic, MN, US) and 20 right ventricular septal pacing (RVSP) with regular active fixation lead respectively in the same period (the LLL-LBBAP group and RVSP group) were compared using ECG characteristics, pacing parameters and complications during 6-month follow-up.

RESULTS

LBBAP was successful with SDL in 23 of 25 patients (92%) and 20 of them were paced with SDL first. In the SDL-LBBAP group, the average age was 70.4 ± 8.2 years, and 55% of patients were male. Paced QRS duration and the stimulus to peak left ventricular activation time (Sti-LVAT) in SDL-LBBAP group were similar with those in LLL-LBBAP group and significantly shorter than those in RVSP group (126.1±14.1ms vs 124.8±10.9ms, P = 1.00; 77.7±11.2ms vs 73.5±9.3ms, P = 0.75; 126.1±14.1ms vs 147.7±22.5ms, P<0.001; 77.7±11.2ms vs 97.0±13.2ms, P<0.001). The pacing threshold and R-wave amplitude of SDL-LBBAP group were 0.53±0.18V and 11.53±3.63mV at baseline respectively, which were comparable with the other two groups. During the 6-month follow-up, the pacing parameters remained stable and no lead-related complication was recorded.

CONCLUSION

It is feasible and safe to use stylet-directed pacing lead for permanent LBBAP without a delivery sheath. Similar to LLL, LBBAP using SDL showed stable parameters and narrower paced QRS duration compared with RVSP, which could be an alternative to LLL in LBBAP. This article is protected by copyright. All rights reserved.

Left Bundle Branch Area Pacing in a Giant Atrium With Atrial Standstill: A Case Report and Literature Review

Atrial standstill (AS) is a rare condition defined by the lack of atrial electrical and mechanical activities. It is usually clinically manifested as symptomatic bradycardia, which requires permanent pacemaker (PPM) implantation. Traditional right ventricular apical pacing causes electrical and mechanical dyssynchrony resulting in left ventricular dysfunction, heart failure, and arrhythmias. As a novel physiological pacing strategy, left bundle branch area pacing (LBBaP) has demonstrated effectiveness and safety in recent years, but its application in exceptional conditions is rarely reported. We report the case of a 47-year-old female, who was diagnosed with AS complicated with a giant atrium, and successfully received a single-chamber PPM with LBBaP.

Evaluation of clinical safety and efficacy of left bundle branch area pacing in comparison with right ventricular septal pacing

ABSTRACT

Left bundle branch area pacing (LBBaP) has recently emerged as a new physiological pacing strategy. The purpose of this study is to compare LBBaP with right ventricular sepal pacing (RVSP) in terms of their clinical safety and efficacy.From February 2019 to May 2020, consecutive pacing-indicated patients were prospectively enrolled and divided into 2 groups. Ventricular synchrony indexes such as QRS duration (QRSd), interventricular mechanical delay and septal-posterior wall motion delay, left ventricular function such as left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF), pacing parameters, and complications were evaluated in the perioperative period and during follow-up.LBBaP was successful in 45 patients (88.2%), and finally 46 patients underwent RVSP. With LBBaP, ventricular electricalmechanical synchrony were similar to those of native-conduction system (P = .78). However, the ventricular electrical synchrony (QRSd, 108.47±7.64 vs 130.63±13.63ms, P < .001) and mechanical synchrony (interventricular mechanical delay, 27.68±4.33 vs 39.88±5.83, P < .001; septal-posterior wall motion delay, 40.39±23.21 vs 96.36±11.55, P < .001) in the LBBaP group were significantly better than those in the RVSP group. No significant differences in LVEDD (46 [44-48.5] vs 47 [44-52] mm, P = .49) and LVEF% (66 [62.5-70] vs 64 [61-68], P = .76) was observed between 2 groups at last follow-up. But, in the subgroup analysis, LVEDD was shorter (46 [44-49] vs 50 [47-58] mm, P = .03) and the LVEF% was higher (65 [62-68] vs 63 [58-65], P = .02) in the LBBaP-H (high ventricular pacing ratio >40%) group compared with RVSP-H group at last follow-up. There were lower capture thresholds (0.59±0.18V vs 0.71 ± 0.26 V, P = 0.01) at implantation in the LBBaP group than those in the RVSP group, with R-wave amplitudes and pacing impedances showing no significant difference between 2 groups. No serious complications were found in both 2 groups at implantation and follow-ups.This study confirms the clinical safety and efficacy of LBBaP, and it produces better ventricular electrical-mechanical synchrony than RVSP. The event of pacing-induced left ventricular dysfunction is lower in the LBBaP-H group than RVSP-H group.

Is the pacing site closer to the left ventricular septal endocardium in left bundle branch pacing or in left ventricular septal pacing?

PURPOSE

Distinguishing between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) is challenging. This study aimed to compare the echocardiographic distance from the pacing lead tip to the left ventricular (LV) septal endocardium between patients who underwent LBBP and those who underwent LVSP successfully.

METHODS

Fifty-nine consecutive patients (age 71.9 ± 12.0 years, 35.6% male) with traditional indications for permanent cardiac pacing were included (LBBP group, n = 46; LVSP group, n = 13). Unipolar pacing from the final pacing sites generated narrow QRS complexes with a right bundle branch block pattern in all patients. After the procedure, a physician blinded to the group allocation performed echocardiographic measurements of the distance between the lead tip and the LV septal endocardium.

RESULTS

The mean paced QRS duration was comparable between the LBBP group and the LVSP group (105.3 ± 15.6 ms vs. 109.2 ± 9.6 ms, P = 0.287). In the LBBP group, the interval from the left bundle branch potential to QRS onset was 28.7 ± 9.0 ms. During diastole, the mean distance between the lead tip and the LV septal endocardium was 0.6 ± 0.9 mm in the LBBP group and 3.0 ± 1.6 mm in the LVSP group (P < 0.001). During systole, the distance was 1.5 ± 1.4 mm in the LBBP group and 4.3 ± 2.6 mm in the LVSP group (P < 0.001).

CONCLUSIONS

The landing zone of the lead tip was closer to the LV septal endocardium in the patients who underwent LBBP. There is a need for real-time intraprocedural monitoring of the distance between the lead tip and the LV septal endocardium when performing LBBP.

Medium- and Long-Term Lead Stability and Echocardiographic Outcomes of Left Bundle Branch Area Pacing Compared to Right Ventricular Pacing

The long-term lead stability and echocardiographic outcomes of left bundle branch area pacing (LBBAP) are not fully understood. This study aimed to observe the mid-long-term clinical impact of LBBAP compared to right ventricular pacing (RVP). Consecutive bradycardia patients undergoing LBBAP or RVP were enrolled. Pacing and electrophysiological characteristics, echocardiographic measurements, and procedural complications were prospectively recorded at baseline and follow-up. LBBAP was successful in 376 of 406 patients (92.6%), while 313 patients received RVP. During a mean follow-up of 13.6 ± 7.8 months, LBBAP presented with similar pacing parameters and complications to RVP, except a significantly narrower paced QRS duration (115.7 ± 12.3 ms vs. 148.0 ± 18.0 ms, p < 0.001). In 228 patients with ventricular pacing burden >40%, LBBAP at last follow-up resulted in decreased left atrial diameter (LAD) (40.1 ± 8.5 mm vs. 38.5 ± 8.0 mm, p < 0.001) while RVP produced decreased left ventricular ejection fraction (62.7 ± 4.8% vs. 60.5 ± 6.9%, p < 0.001) when compared to baseline. After adjusting for age, the presence of atrial fibrillation, and other clinical factors, LBBAP was still associated with a decrease in LAD (-1.601, 95% CI -3.094--0.109, p = 0.036). We conclude that LBBAP might result in more preserved echocardiographic outcomes than RVP.

Left bundle branch area pacing guided by continuous uninterrupted monitoring of unipolar pacing characteristics

INTRODUCTION

During left bundle branch area pacing (LBBAP) lead implantation, intermittent monitoring of unipolar pacing characteristics confirms LBB capture and can detect septal perforation. We aimed to demonstrate that continuous uninterrupted unipolar pacing from an inserted lead stylet (LS) is feasible and facilitates LBBAP implantation.

METHODS

Thirty patients (mean age 76 ± 14 years) were implanted with a stylet-driven pacing lead (Biotronik Solia S60). In 10 patients (comparison-group) conventional implantation with interrupted unipolar pacing was performed, with comparison of unipolar pacing characteristics between LS and connector-pin (CP)-pacing after each rotation step. In 20 patients (uninterrupted-group) performance and safety of uninterrupted implantation during continuous pacing from the LS were evaluated.

RESULTS

In the comparison group, LS and CP-pacing impedances were highly correlated (R²  = 0.95, p < .0001, bias 12 ± 37 Ω) with comparable sensed electrograms and paced QRS morphologies. In the uninterrupted group, continuous LS-pacing allowed beat-to-beat monitoring of impedance and QRS morphology to guide implantation. This resulted in successful LBBAP in all patients, after a mean of 1 ± 0 attempts, with mean threshold 0.81 ± 0.4 V, median sensing 6.5 mV [IQR 4.4-9.5], and mean impedance 624 ± 101 Ω. Positive LBBAP-criteria were seen in all patients with median paced QRS duration of 120 ms [IQR 112-152 ms] and median pLVAT 73 ms [IQR 68-80.5 ms]. No septal perforation occurred.

CONCLUSION

Unipolar pacing from the LS allows accurate determination of pacing impedance and generates similar paced QRS morphologies and sensed electrograms to CP pacing. Continuous LS pacing allows real-time monitoring of impedance and paced QRS morphology, which facilitates safe and successful LBBAP lead implantation.

Comparison of Procedure and Fluoroscopy Time Between Left Bundle Branch Area Pacing and Right Ventricular Pacing for Bradycardia: The Learning Curve for the Novel Pacing Strategy

Background: Left bundle branch area pacing (LBBAP) is a novel physiological pacing approach.

Objective: To assess learning curve for LBBAP and compare the procedure and fluoroscopy time between LBBAP and right ventricular pacing (RVP).

Methods: Consecutive bradycardia patients who underwent LBBAP or RVP were prospectively recruited from June 2018 to June 2020. The procedure and fluoroscopy time for ventricular lead placement, pacing parameters, and periprocedural complications were recorded. Restricted cubic splines were used to fit learning curves for LBBAP.

Results: Left bundle branch area pacing was successful in 376 of 406 (92.6%) patients while 313 patients received RVP. Learning curve for LBBAP illustrated initial (1–50 cases), improved (51–150 cases), and stable stages (151–406 cases) with gradually increased success rates (88.0 vs. 90.0 vs. 94.5%, P = 0.106), steeply decreased median procedure (26.5 vs. 14.0 vs. 9.0min, P < 0.001) and fluoroscopy time (16.0 vs. 6.0 vs. 4.0min, P < 0.001), and shortened stimulus to left ventricular activation time (Sti-LVAT; 78.7 vs. 78.1 vs. 71.2 ms, P < 0.001). LBBAP at the stable stage showed longer but close median procedure (9.0 vs. 6.9min, P < 0.001) and fluoroscopy time (4.0 vs. 2.8min, P < 0.001) compared with RVP.

Conclusion: The procedure and fluoroscopy time of LBBAP could be reduced significantly with increasing procedure volume and close to that of RVP for an experienced operator.

Retrograde penetration pacing into the conduction system as an alternative approach of his-bundle pacing: Retrograde penetration pacing into the conduction system

BACKGROUND

The optimal right ventricular (RV) pacing site during pacemaker implantation is still unclear due to left ventricular (LV) dyssynchrony by traditional RV pacing. His-bundle (HIS) pacing has achieved narrow QRS and maintained LV synchrony but high failure rate. RV septal pacing occasionally has QRS waveform with wide and narrow component in the early and late phase, respectively, and maintains LV synchrony, reflecting the normal conduction system. We aimed to define this QRS waveform as retrograde penetration pacing into the conduction system (RPP-CS) and compared its effect on LV synchrony as an alternative approach of HIS pacing.

METHODS AND RESULTS

We enrolled 42 patients with atrio ventricular block (AVB) or bradycardia atrial fibrillation (AF) requiring pacemaker implantation (RPP-CS, n = 27; no RPP-CS, n = 15). Baseline characteristics were similar between the groups. RPP-CS was observed in 96% and 26% of the RV septum and apex area, respectively. RPP-CS had a significantly shorter QRS width (p < 0.001). The frequency of maintaining LV synchrony was significantly higher in RPP-CS (67% vs. 20%, p = 0.003). The QRS interval's optimal cut-off value during RPP-CS was 132 ms for prediction of LV synchrony (sensitivity 83%, specificity 89%, positive predictive value 94%, and negative predictive value 73%). During RPP-CS, shorter QRS intervals (QRS ≤ 132 ms) had better postoperative LV ejection fraction than longer intervals (p < 0.001).

CONCLUSIONS

RPP-CS, especially with short QRS intervals (≤132 ms), had a high frequency of LV synchrony, maintained postoperative cardiac function, and may be an adequate first-line RV pacing site strategy for AVB or bradycardia AF as an alternative approach of HIS pacing.

Comparison of efficacy and safety of His-Purkinje system pacing versus cardiac resynchronisation therapy in patients with pacing-induced cardiomyopathy: protocol for a randomised controlled trial

INTRODUCTION

Recent studies have shown that the His-Purkinje system pacing (HPSP) can achieve electrocardiomechanical synchronisation, and thus improve cardiac function. For patients with pacing-induced cardiomyopathy (PICM) who should be treated with pacemaker upgrade, the HPSP is a viable alternative to cardiac resynchronisation therapy (CRT). However, no randomised controlled trial has been performed to evaluate the efficacy and safety of HPSP in patients with PICM. The present study compared the efficacy and safety of HPSP with that of traditional CRT in the treatment of patients with PICM.

METHODS AND ANALYSIS

This study is a single-centre, randomised controlled non-inferiority trial. This trial was carried out at the cardiac centre of Beijing Anzhen Hospital. A total of 46 patients with PICM who needed pacemaker upgrade treatment between January 2022 and December 2023 will be enrolled in this study. Patients will be randomised into an investigational group (HPSP) and a control group (CRT) at a 1:1 ratio. The primary outcome is the duration of QRS complex (QRS width), and the secondary outcomes are NT-proBNP (N terminal pro B type natriuretic peptide), C reactive protein, the number of antibiotics used, left ventricular ejection fraction, end systolic volume, end diastolic volume, the hospitalisation duration, the incidence of postoperative infection, pacemaker parameters (threshold, sensing and impedance), the 6-minute walking test, and quality of life (36-Item Short Form Survey scale), all-cause mortality, cardiovascular death, heart failure-related rehospitalisation rate, other rehospitalisation rates, major complication rates and procedure costs.

ETHICS AND DISSEMINATION

This study has been approved by the Beijing Anzhen Hospital Medical Ethics Committee (No. 2020043X).

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2000034265).

Multi-Axis Lead with Tetrahedral Electrode Tip for Cardiac Implantable Devices: Creative Concept for Pacing and Sensing Technology

BACKGROUND

We developed a multi-axis lead (Max_Lead) incorporating four electrodes arranged at the lead-tip organized in an equidistant tetrahedron. Here, we studied Max_Lead performance in sensing, pacing and activation wavefront-direction analysis.

METHODS

Sixteen explanted animal hearts (from 7 pigs, 7 sheep and 2 rabbits) were used. Pacing threshold was tested from all axes of Max_Lead from RV apex before and after simulated dislodgement. Additionally, conduction-system pacing was performed in sheep heart preparations from all axes of Max_Lead. Sensing via Max_Lead positioned at RV apex was tested during sinus rhythm (SR), pacing from RV and LV free-wall, and ventricular fibrillation (VF). Max_Lead-enabled voltage (Max^V), defined as the largest span of the sensed electric field loop, was compared to traditional lead-tip voltage detection.

RESULTS

Pacing: Max_Lead minimized change in pacing threshold due to lead-dislodgement (average voltage change 0.2 mV, 95% CI (-0.5, 0.9)), using multiple bipoles available for pacing. In animals with high conduction system pacing thresholds (>2mV) in one or more bipoles (3/7), acceptable thresholds (<1 mV) were demonstrated in an average of 2.5 remaining bipoles. Sensing: Max^V of SR and VF was consistently higher than the highest bipolar voltage (voltage difference averaged -0.18 mV, 95% confidence interval (CI: -0.28 to -0.07), p=0.001). Electric field loop geometry consistently differentiated ventricular activation in SR from that during pacing from RV and LV free walls.

CONCLUSIONS

The multi-axis Max_Lead electrode showed advantages in pacing, sensing and mapping and has the potential to allow for improvements in lead/electrode technology for cardiac implanted electronic devices.

Safety and efficacy of left bundle branch pacing in comparison with conventional right ventricular pacing: A systematic review and meta-analysis

BACKGROUND

Right ventricular pacing (RVP) has been widely accepted as a traditional pacing strategy, but long-term RVP has detrimental impact on ventricular synchrony. However, left bundle branch pacing (LBBP) that evolved from His-bundle pacing could maintain ventricular synchrony and overcome its clinical deficiencies such as difficulty of lead implantation, His bundle damage, and high and unstable thresholds. This analysis aimed to appraise the clinical safety and efficacy of LBBP.

METHODS

The Medline, PubMed, Embase, and the Cochrane Library databases from inception to November 2020 were searched for studies comparing LBBP and RVP.

RESULTS

Seven trials with 451 patients (221 patients underwent LBBP and 230 patients underwent RVP) were included in the analysis. Pooled analyses verified that the paced QRS duration (QRSd) and left ventricular mechanical synchronization parameters of the LBBP capture were similar with the native-conduction mode (P > .7),but LBBP showed shorter QRS duration (weighted mean difference [WMD]: -33.32; 95% confidence interval [CI], -40.44 to -26.19, P < .001), better left ventricular mechanical synchrony (standard mean differences: -1.5; 95% CI: -1.85 to -1.14, P < .001) compared with RVP. No significant differences in Pacing threshold (WMD: 0.01; 95% CI: -0.08 to 0.09, P < .001), R wave amplitude (WMD: 0.04; 95% CI: -1.12 to 1.19, P = .95) were noted between LBBP and RVP. Ventricular impedance of LBBP was higher than that of RVP originally (WMD: 19.34; 95% CI: 3.13-35.56, P = .02), and there was no difference between the 2 groups after follow-up (WMD: 11.78; 95% CI: -24.48 to 48.04, P = .52). And follow-up pacing threshold of LBBP kept stability (WMD: 0.08; 95% CI: -0.09 to 0.25, P = .36). However, no statistical difference existed in ejection fraction between the 2 groups (WMD: 1.41; 95% CI: -1.72 to 4.54, P = .38).

CONCLUSIONS

The safety and efficacy of LBBP was firstly verified by meta-analysis to date. LBBP markedly preserve ventricular electrical and mechanical synchrony compared with RVP. Meanwhile, LBBP had stable and excellent pacing parameters. However, LBBP could not be significant difference in ejection fraction between RVP during short- term follow-up.

Efficacy and safety of left bundle branch area pacing versus right ventricular apex pacing in patients with atrioventricular block: study protocol for a randomised controlled trial

INTRODUCTION

Left bundle branch area pacing (LBBaP) is a relatively new approach for physiologic pacing. A limited number of retrospective clinical studies, featuring small sample sizes, have shown that compared with right ventricular apex pacing (RVAP), the QRS duration of postoperative ECG in LBBaP patients is narrower and the cardiac systolic function is improved. However, there have been no randomised controlled trials (RCTs) evaluating the efficacy and safety of LBBaP in patients with atrioventricular block (AVB). Therefore, the current study intends to address the paucity in RCT data evaluating LBBaP versus RVAP in AVB patients.

ANALYSIS AND METHODS

This study is a single-centre, randomised controlled superiority trial to be conducted at the Cardiac Centre of Beijing Anzhen Hospital. From January 2021 to December 2023, 210 consecutive AVB patients meeting the inclusion criteria and receiving pacemaker implantation will be enrolled. Participants will be randomly divided into an experimental group (LBBaP) and a control group (RVAP) at a 1:1 ratio. The primary outcome is left ventricular ejection fraction (LVEF), which will be assessed by echocardiography. The secondary outcomes in this study are synchrony of left ventricular systole, NT-proBNP, LVEDD, the 6-min walk distance, quality of life (SF-36 scale), all-cause mortality, cardiovascular death events, rehospitalisation rate and major complication rate.

ETHICS AND DISSEMINATION

This study was approved by the Medical Ethics Committee of Beijing Anzhen Hospital (No. 2020021X). The results of the trial will be presented at national and international conferences. We hypothesise that compared with RVAP, LBBaP will be superior for treating patients with AVB. This trial will provide evidence-based suggestion for the majority of electrophysiologists in pacing implantation.

TRIAL REGISTRATION

ChiCTR2000034335.

Physiology-based electrocardiographic criteria for left bundle branch capture

BACKGROUND

During left bundle branch (LBB) area pacing, it is important to confirm that capture of the LBB, and not just capture of only adjacent left ventricular (LV) myocardium, has been achieved.

OBJECTIVE

The purpose of this study was to establish electrocardiographic (ECG) criteria for LBB capture. We hypothesized that because LBB pacing results in physiological depolarization of the LV, then the native QRS can serve as a reference for diagnosis of LBB capture in the same patient.

METHODS

Only patients with evidence of LBB capture (QRS morphology transition) were included. Several QRS characteristics were compared between the native rhythm and different types of LBB area capture.

RESULTS

A total of 357 ECGs (124 patients) were analyzed: 118 with native rhythm, 124 with nonselective LBB capture, 69 with selective LBB capture, and 46 with LV septal capture. Our hypotheses that during LBB capture the paced V6 R-wave peak time (RWPT; measured from QRS onset) equals the native V6 RWPT and that the paced V6 RWPT (measured from the stimulus) equals the LBB potential to V6 R-wave peak interval were positively validated. Criteria based on these rules had sensitivity and specificity of 88.2%-98.0% and 85.7%-95.4%, respectively. Moreover, 100% specific V6 RWPT cutoff for LBB capture diagnosis in patients with narrow QRS/right bundle branch block was determined to be 74 ms.

CONCLUSION

We showed equivalency of LV activation times on ECG during native and paced LBB conduction. Therefore, if V6 RWPT is longer during pacing, this finding is indicative of lack of LBB capture.

Left Bundle Branch Area Pacing vs. Biventricular Pacing for Cardiac Resynchronization Therapy: A Meta-Analysis

Background: Left bundle branch area pacing (LBBAP) is a recently proposed method for conduction system pacing. We performed a meta-analysis of controlled studies to compare the clinical outcome in patients who received LBBAP vs. biventricular pacing (BVP) for cardiac resynchronization therapy (CRT).

Methods: PubMed, Embase, and Cochrane's Library databases were searched for relevant controlled studies. A random-effect model incorporating the potential heterogeneity was used to synthesize the results.

Results: Four non-randomized controlled studies including 249 patients with heart failure (HF) for CRT were included, and the patients were followed for 6–12 months. Compared with BVP, LBBAP was associated with significantly shortened QRS duration [mean difference (MD): −29.18 ms, 95% confidence interval (CI): −33.55–24.80, I² = 0%, P < 0.001], improved left ventricular ejection fraction (MD: 6.93%, 95% CI: 4.69–9.17, I² = 0%, P < 0.001), reduced left ventricular end-diastolic dimension (MD: −2.96 mm, 95% CI: −5.48 to −0.44, I² = 0%, P = 0.02), and improved New York Heart Association class (MD: −0.54, 95% CI: −0.84 to −0.24, I² = 65%, P < 0.001). Moreover, patients who received LBBAP were more likely to achieve echocardiographic [odds ratio (OR): 5.04, 95% CI: 2.17–11.69, I² = 0%, P < 0.001] and clinical (OR: 7.33, 95% CI: 1.62–33.16, I² = 0%, P = 0.01) CRT responses.

Conclusion: Current evidence from non-randomized studies suggests that LBBAP appears to be a promising method for CRT, which is associated with more remarkable improvements of symptoms and cardiac function in HF patients with indication for CRT.

Relationship of paced left bundle branch pacing morphology with anatomic location and physiological outcomes

BACKGROUND

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. However, little is known about pacing at different locations on the left bundle branch (LBB).

OBJECTIVE

The purpose of this study was to explore pacing and physiological characteristics associated with different LBBP locations.

METHODS

The study included 68 consecutive patients with normal unpaced QRS duration and successful LBBP implantation. Patients were divided into 3 groups according to the paced QRS complex as left bundle branch trunk pacing (LBTP), left posterior fascicular pacing (LPFP), or left anterior fascicular pacing (LAFP). Electrocardiographic (ECG) characteristics, pacing parameters, and fluoroscopic localization were collected and analyzed.

RESULTS

There were 17 (25.0%), 35 (51.5%), and 16 (23.5%) patients in the LBTP, LPFP, and LAFP groups, respectively. All subgroups had relatively narrow paced QRS complex (128.6 ± 9.1 ms vs 133.7 ± 11.2 ms vs 134.8 ± 9.6 ms; P = .170), fast left ventricular activation (70.4 ± 9.0 ms vs 70.6 ± 10.2 ms vs 71.0 ± 9.0 ms; P = .986), as well as low and stable pacing thresholds. Delayed right ventricular activation and interventricular dyssynchrony were similar between groups. Fluoroscopic imaging indicated that the lead tip was located most commonly in the basal-middle region of the septum (67.7%), and this was independent of paced QRS morphology group (88.2% vs 57.1% vs 68.8%; P = .106).

CONCLUSION

Pacing at different sites of the LBB resulted in similar intraventricular and interventricular electrical synchrony in patients with an intact conduction system. Fluoroscopic imaging alone could not predict specific LBBP paced ECG morphology.

Efficacy and safety of left bundle branch area pacing versus biventricular pacing in heart failure patients with left bundle branch block: study protocol for a randomised controlled trial

INTRODUCTION

Left bundle branch area pacing (LBBaP) has been accepted as a physiological pacing method that can yield narrow paced QRS waves. For patients with failed biventricular pacing (Bi-V), LBBaP is another feasible option. However, no randomised controlled study has evaluated the efficacy and safety of LBBaP in heart failure patients with left bundle branch block (LBBB). Therefore, we aimed to conduct this type of randomised controlled trial.

METHODS AND ANALYSIS

This study is a single-centre, randomised controlled non-inferiority trial. This study will be conducted at the cardiac centre of Beijing Anzhen Hospital. From January 2020 to December 2022, 180 heart failure patients with reduced left ventricular ejection fraction (LVEF ≤35%) and LBBB undergoing Bi-V implantation will be consecutively enrolled in this study. Participants will be randomised at a 1:1 ratio into an experimental group (LBBaP) and a control group (Bi-V). The primary outcome is LVEF. The secondary outcomes are NT-proBNP, duration of the QRS complex, end systolic volume, end diastolic volume, the 6-minute walking test and quality of life (SF-36 scale), all causes of mortality, cardiovascular death, rehospitalisation rate of heart failure, other rehospitalisation rates, major complication rates, procedure costs and hospitalised dates.

ETHICS AND DISSEMINATION

This study has been approved by the Beijing Anzhen Hospital Medical Ethics Committee (No. ks201932). The results of this study will be presented at domestic and international conferences. We hypothesise that LBBaP is non-inferior compared with Bi-V for treating patients with heart failure and LBBB. This trial will provide evidence-based recommendations for electrophysiologists.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2000028726).