Evaluation of cardiac synchrony in left bundle branch pacing: Insights from echocardiographic research

Enhancing cardiac pacing strategies: a review of conduction system pacing compared with right and biventricular pacing and their influence on myocardial function

Traditional right ventricular pacing (RVP) has been linked to the deterioration of both left ventricular diastolic and systolic function. This worsening often culminates in elevated rates of hospitalization due to heart failure, an increased risk of atrial fibrillation, and increased morbidity. While biventricular pacing (BVP) has demonstrated clinical and echocardiographic improvements in patients afflicted with heart failure and left bundle branch block, it has also encountered significant challenges such as a notable portion of non-responders and procedural failures attributed to anatomical complexities. In recent times, the interest has shifted towards conduction system pacing, initially, His bundle pacing, and more recently, left bundle branch area pacing, which are seen as promising alternatives to established methods. In contrast to other approaches, conduction system pacing offers the advantage of fostering more physiological and harmonized ventricular activation by directly stimulating the His-Purkinje network. This direct pacing results in a more synchronized systolic and diastolic function of the left ventricle compared with RVP and BVP. Of particular note is the capacity of conduction system pacing to yield a shorter QRS, conserve left ventricular ejection fraction, and reduce rates of mitral and tricuspid regurgitation when compared with RVP. The efficacy of conduction system pacing has also been found to have better clinical and echocardiographic improvement than BVP in patients requiring cardiac resynchronization. This review will delve into myocardial function in conduction system pacing compared with that in RVP and BVP.

Comparison between left bundle branch area pacing and right ventricular pacing: ventricular electromechanical synchrony and risk of atrial high-rate episodes

Background

The electromechanical dyssynchrony associated with right ventricular pacing (RVP) has been found to have adverse impact on clinical outcomes. Several studies have shown that left bundle branch area pacing (LBBAP) has superior pacing parameters compared with RVP. We aimed to assess the difference in ventricular electromechanical synchrony and investigate the risk of atrial high-rate episodes (AHREs) in patients with LBBAP and RVP.

Methods

We consecutively identified 40 patients with atrioventricular block and no prior atrial fibrillation. They were divided according to the ventricular pacing sites: the LBBAP group and the RVP group (including the right ventricular apical pacing (RVA) group and the right side ventricular septal pacing (RVS) group). Evaluation of ventricular electromechanical synchrony was implemented using electrocardiogram and two-dimensional speckle tracking echocardiography (2D-STE). AHRE was defined as event with an atrial frequency of ≥176 bpm lasting for ≥6 min recorded by pacemakers during follow-up.

Results

The paced QRS duration of the LBBAP group was significantly shorter than that of the other two groups: LBBAP 113.56 ± 9.66 ms vs. RVA 164.73 ± 14.49 ms, p < 0.001; LBBAP 113.56 ± 9.66 ms vs. RVS 148.23 ± 17.3 ms, p < 0.001. The LBBAP group showed shorter maximum difference (TDmax), and standard deviation (SD) of the time to peak systolic strain among the 18 left ventricular segments, and time of septal-to-posterior wall motion delay (SPWMD) compared with the RVA group (TDmax, 87.56 ± 56.01 ms vs. 189.85 ± 91.88 ms, p = 0.001; SD, 25.40 ± 14.61 ms vs. 67.13 ± 27.40 ms, p < 0.001; SPWMD, 28.75 ± 21.89 ms vs. 99.09 ± 46.56 ms, p < 0.001) and the RVS group (TDmax, 87.56 ± 56.01 ms vs. 156.46 ± 55.54 ms, p = 0.003; SD, 25.40 ± 14.61 ms vs. 49.02 ± 17.85 ms, p = 0.001; SPWMD, 28.75 ± 21.89 ms vs. 91.54 ± 26.67 ms, p < 0.001). The interventricular mechanical delay (IVMD) was shorter in the LBBAP group compared with the RVA group (-5.38 ± 9.31 ms vs. 44.82 ± 16.42 ms, p < 0.001) and the RVS group (-5.38 ± 9.31 ms vs. 25.31 ± 21.36 ms, p < 0.001). Comparing the RVA group and the RVS group, the paced QRS duration and IVMD were significantly shorter in the RVS group (QRS duration, 164.73 ± 14.49 ms vs. 148.23 ± 17.3 ms, p = 0.02; IVMD, 44.82 ± 16.42 ms vs. 25.31 ± 21.36 ms, p = 0.022). During follow-up, 2/16 (12.5%) LBBAP patients, 4/11 (36.4%) RVA patients, and 8/13 (61.5%) RVS patients had recorded novel AHREs. LBBAP was proven to be independently associated with decreased risk of AHREs than RVP (log-rank p = 0.043).

Conclusion

LBBAP generates narrower paced QRS and better intro-left ventricular and biventricular contraction synchronization compared with traditional RVP. LBBAP was associated with a decreased risk of AHREs compared with RVP.

Left bundle branch pacing better preserves ventricular mechanical synchrony than right ventricular pacing: a two-centre study

AIMS

Left bundle branch pacing (LBBP) has been shown to better maintain electrical synchrony compared with right ventricular pacing (RVP), but little is known about its impact on mechanical synchrony. This study investigates whether LBBP better preserves left ventricular (LV) mechanical synchronicity and function compared with RVP.

METHODS AND RESULTS

Sixty patients with pacing indication for bradycardia were included: LBBP (n = 31) and RVP (n = 29). Echocardiography was performed before and shortly after pacemaker implantation and at 1-year follow-up. The lateral wall-septal wall (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking, and septal strain patterns were also assessed. At baseline, LW-SW work difference was small and similar in two groups. SW was markedly decreased, while LW work remained mostly unchanged in RVP, resulting in a larger LW-SW work difference compared with LBBP (1253 ± 687 mmHg·% vs. 439 ± 408 mmHg·%, P < 0.01) at last follow-up. In addition, RVP more often induced septal flash or apical rocking and resulted in more advanced strain patterns compared with LBBP. At 1 year follow-up, LV ejection fraction (EF) and global longitudinal strain (GLS) were more decreased in RVP compared with LBBP (ΔLVEF: -7.4 ± 7.0% vs. 0.3 ± 4.1%; ΔLVGLS: -4.8 ± 4.0% vs. -1.4 ± 2.5%, both P < 0.01). In addition, ΔLW-SW work difference was independently correlated with LV adverse remodelling (r = 0.42, P < 0.01) and LV dysfunction (ΔLVEF: r = -0.61, P < 0.01 and ΔLVGLS: r = -0.38, P = 0.02).

CONCLUSION

LBBP causes less LV mechanical dyssynchrony than RVP as it preserves a more physiologic electrical conduction. As a consequence, LBBP appears to preserve LV function better than RVP.

Safety and efficacy of left bundle branch area pacing compared with right ventricular pacing in patients with bradyarrhythmia and conduction system disorders: Systematic review and meta-analysis

BACKGROUND

Right Ventricular Pacing (RVP) may have detrimental effects in ventricular function. Left Bundle Branch Area Pacing (LBBAP) is a new pacing strategy that appears to have better results. The aim of this systematic review and meta-analysis is to compare the safety and efficacy of LBBAP vs RVP in patients with bradyarrhythmia and conduction system disorders.

METHODS

MEDLINE, EMBASE and Pubmed databases were searched for studies comparing LBBAP with RVP. Outcomes were all-cause mortality, atrial fibrillation (AF) occurrence, heart failure hospitalizations (HFH) and complications. QRS duration, mechanical synchrony and LVEF changes were also assessed. Pairwise meta-analysis was conducted using random and fixed effects models.

RESULTS

Twenty-five trials with 4250 patients (2127 LBBAP) were included in the analysis. LBBAP was associated with lower risk for HFH (RR:0.33, CI 95%:0.21 to 0.50; p < 0.001), all-cause mortality (RR:0.52 CI 95%:0.34 to 0.80; p = 0.003), and AF occurrence (RR:0.43 CI 95%:0.27 to 0.68; p < 0.001) than RVP. Lead related complications were not different between the two groups (p = 0.780). QRSd was shorter in the LBBAP group at follow-up (WMD: -32.20 msec, CI 95%: -40.70 to -23.71; p < 0.001) and LBBAP achieved better intraventricular mechanical synchrony than RVP (SMD: -1.77, CI 95%: -2.45 to -1.09; p < 0.001). LBBAP had similar pacing thresholds (p = 0.860) and higher R wave amplitudes (p = 0.009) than RVP.

CONCLUSIONS

LBBAP has better clinical outcomes, preserves ventricular electrical and mechanical synchrony and has excellent pacing parameters, with no difference in complications compared to RVP.

Comparison of ventricular synchrony in children with left bundle branch area pacing and right ventricular septal pacing

OBJECTIVE

This study aimed to determine the ideal pacing site in children by comparing the postoperative ventricular synchrony in children with left bundle branch area pacing and those with right ventricular septal pacing.

METHODS

This retrospective study included children with complete atrioventricular block who underwent permanent pacemaker implantation from March 2019 to August 2021. Patients were grouped according to their ventricular pacing site, the left bundle branch area pacing group and the right ventricular septal pacing group. Two-dimensional speckle tracking echocardiography was used to evaluate the ventricular synchrony.

RESULTS

Forty-eight children (median age, 2.7 years; interquartile range, 1.7-4.6 years) were included. The paced QRS duration in the left bundle branch area pacing group was significantly narrower than that in the right ventricular septal pacing group (100.2 ± 9.3 versus 115.4 ± 15.1 ms, p = 0.001). The median follow-up duration was 1.5 years (interquartile range, 1-2 years). At the last follow-up, the average capture threshold of the ventricular electrode in the left bundle branch area pacing group was lower than that in the right ventricular septal pacing group (0.79 ± 0.18 versus 1.20 ± 0.56 V, p = 0.008). The left ventricular intraventricular synchrony parameters in the left bundle branch area pacing group were better than those in the right ventricular septal pacing group (e.g. standard deviation of the time to peak longitudinal strain, 37.4 ± 4.3 versus 46.6 ± 8.2 ms, p = 0.000). The average interventricular mechanical delay time in the left bundle branch area pacing group was significantly shorter than that in the right ventricular septal pacing group (36.4 ± 14.2 versus 52.5 ± 22.7 ms, p = 0.016).

CONCLUSION

Compared with right ventricular septal pacing, left bundle branch area pacing in children produces a narrower QRS duration and better pacing and ventricular synchrony parameters postoperatively.

Use of acoustic cardiography to assess left ventricular electromechanical synchronization during left bundle branch pacing

Background

Left bundle branch pacing (LBBP) is a physiological pacing that captures the main left bundle or its proximal branch. Electromechanical activation time (EMAT) is an acoustic cardiographic metric that provides a simple method for evaluating left ventricular (LV) synchrony. Prolonged EMAT reflects impaired LV electromechanical coupling.

Objective

The purpose of this study was to explore whether EMAT can confirm that LBBP produces more satisfactory LV electromechanical synchronization than conventional right ventricular pacing modalities.

Methods

Patients with standard pacing indications and narrow QRS duration were recruited for this study. Unipolar pacing under 3 different modalities-right ventricular apical pacing (RVAP), right ventricular high septal pacing (RVHSP), and LBBP-were successively performed in each patient. Pacing parameters, echocardiographic characteristics, and acoustic cardiographic parameters at different pacing modalities and during normal rhythm were collected.

Results

A total of 55 patients were enrolled, and all had successful LBBP. Left ventricular activation time (LVAT) was significantly associated with EMAT, with LVAT vs EMAT correlation coefficient of 0.665 (P <.001). LVAT during LBBP was shorter than that during RVHSP (51.93 ± 2.732 ms vs 85.59 ± 2.240 ms; P <.001). EMAT of LBBP was significantly lower than either RVAP or RVHSP (95.44 ± 1.794 ms vs 143.32 ± 2.376 ms, and 132.22 ± 1.872 ms; both P <.001) but was similar to that of intrinsic rhythm (95.37 ± 2.271 ms; P = .862).

Conclusion

We found EMAT significantly prolonged in RVHSP and RVAP but not in the LBBP mode. This finding indicates superior electromechanical synchronization in patients having LBBP. EMAT measurement could be an additional method for identifying the ideal pacing position.

Comparison of the left ventricular dyssynchrony between stylet-driven and lumen-less lead technique in left bundle branch area pacing using myocardial perfusion scintigraphy

Background

Left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing method to reduce left ventricular (LV) dyssynchrony due to ventricular pacing. Only lumen-less pacing leads (LLLs) with fixed helixes could achieve LBBAP previously, but recently, LBBAP has been performed using stylet-driven leads (SDLs). This study aimed to evaluate the LV dyssynchrony between SDLs and LLLs techniques in LBBAP.

Methods

We retrospectively evaluated patients who underwent LBBAP with either SDLs or LLLs. We compared both groups' electrocardiogram (ECG) findings and LV dyssynchrony parameters derived from myocardial perfusion scintigraphy. LV dyssynchrony parameters consisted of phase analysis and regional wall motion analysis. We evaluated bandwidth, phase standard deviation (PSD), and entropy in the phase analysis. The time to the end-systolic frame (TES) was calculated in regional wall motion analysis using single-photon emission computed tomography (SPECT). We also evaluated the maximum differences between segmental TES (MDTES), the standard deviation of TES (SDTES), and the difference in the TES between the lateral wall and septum (DTES-LS).

Results

In total, 97 patients were enrolled. The success rate of LBBAP did not differ between the groups [SDLs: 47/48 patients (98%) vs. LLLs: 47/51 patients (92%), P=0.36]. The paced QRS duration and the stimulus to the peak LV activation time (stim-LVAT) also did not differ between SDL and LLL groups (122±10 vs. 119±12 ms, P=0.206; 69±12 vs. 66±13 ms, P=0.31, respectively). There were no differences in bandwidth, PSD, and entropy between SDL and LLL groups (73°±37° vs. 86°±47°, P=0.18; 19°±8.5° vs. 21°±9.7°, P=0.19; 0.57±0.08 vs. 0.59±0.08, P=0.17, respectively). The regional wall motion analysis parameters MDTES, SDTES, and DTES-LS also did not differ between SDL and LLL groups (19%±10% vs. 20%±10%, P=0.885; 5.0%±2.5% vs. 5.0%±2.5%, P=0.995; 5.0%±3.7% vs. 4.8%±4.2%, P=0.78, respectively).

Conclusions

LBBAP using SDLs was comparable to LV electrical and mechanical synchrony with LLLs.

Echocardiographic Evaluation of the Effect on Left Ventricular Function Between Left Bundle Branch Pacing and Right Ventricular Pacing

Purpose

The purpose of this study was to assess the left ventricular function effects of permanent left bundle branch pacing (LBBP) versus traditional right ventricular pacing (RVP).

Patients and Methods

Consecutive patients receiving pacemaker implantation were included and divided into left bundle branch block (LBBB) group and right ventricular pacing (RVP) group. Baseline characteristics were collected, and they received 1-year follow-up. Electrocardiogram (ECG) characteristics and pacing parameters were assessed before and after implantation. Cardiac function parameters such as left ventricular ejection fraction (LVEF) and tricuspid regurgitation (TR) were recorded and compared.

Results

Of 78 patients included, 45 patients received LBBP (mean age, 72.7 ± 12.2 years; male, 55.6%) and 33 patients underwent RVP (mean age 72.9 ± 11.8 years; male, 63.6%). The pacing parameters were satisfactory during the implantation and remained stable during mid-term follow-up. During the follow-up period, LBBP patients had a greater decrease in LVEDD and LVESD. The TR in the LBBP group was significantly improved as compared to the RVP group (P=0.016).

Conclusion

Permanent LBBP achieves favorable cardiac hemodynamic effects with good stability and safety. LBBP may reduce severe TR at 1-year follow-up, and LBBP may be an option for patients with severe TR.

Pacing of Specialized Conduction System

Right ventricular pacing for bradycardia remains the mainstay of pacing therapy. Chronic right ventricular pacing may lead to pacing-induced cardiomyopathy. We focus on the anatomy of the conduction system and the clinical feasibility of pacing the His bundle and/or left bundle conduction system. We review the hemodynamics of conduction system pacing, the techniques to capture the conduction system and the electrocardiogram and pacing definitions of conduction system capture. Clinical studies of conduction system pacing in the setting of atrioventricular block and after AV junction ablation are reviewed and the evolving role of conduction system pacing is compared with biventricular pacing.

Cardiovascular imaging in conduction system pacing: What does the clinician need?

Permanent pacemakers are used for symptomatic bradycardia and biventricular pacing (BVP)-cardiac resynchronization therapy (BVP-CRT) is established for heart failure (HF) patients traditionally. According to guidelines, patients' selection for CRT is based on QRS duration (QRSd) and morphology by surface electrocardiogram (ECG). Cardiovascular imaging techniques evaluate cardiac structure and function as well as identify pathophysiological substrate changes including the presence of scar. Cardiovascular imaging helps by improving the selection of candidates, guiding left ventricular (LV) lead placement, and optimization devices during the follow-up. Conduction system pacing (CSP) includes His bundle pacing (HBP) and left bundle branch pacing (LBBP) which is screwed into the interventricular septum. CSP maintains and restores ventricular synchrony in patients with native narrow QRSd and left bundle branch block (LBBB), respectively. LBBP is more feasible than HBP due to a wider target area. This review highlights the role of multimodality cardiovascular imaging including fluoroscopy, echocardiography, cardiac magnetic resonance (CMR), myocardial scintigraphy, and computed tomography (CT) in the pre-procedure assessment for CSP, better selection for CSP candidates, the guidance of CSP lead implantation, and the optimization of devices programming after the procedure. We also compare the different characteristics of multimodality imaging and discuss their potential roles in future CSP implantation.

Left bundle branch area pacing prevents pacing induced cardiomyopathy in long-term observation

BACKGROUND

Left bundle branch area pacing (LBBAP) is one of the methods to deliver conduction system pacing which potentially avoids the negative impact of conventional right ventricular pacing.

OBJECTIVE

To assess echocardiographic outcomes in a long-term observation in patients with LBBAP implemented for bradyarrhythmia indications.

METHODS AND RESULTS

A total of 151 patients with symptomatic bradycardia and LBBAP pacemaker implanted, were prospectively included in the study. Subjects with left bundle branch block and CRT indications (n = 29), ventricular pacing burden <40% (n = 11), and loss of LBBAP (n = 10) were excluded from further analysis. At baseline and the last follow-up visit, echocardiography with global longitudinal strain (GLS) assessment, 12-lead ECG, pacemaker interrogation, and blood level of NT-proBNP were performed. The median follow-up period was 23 months (15.5-28). None of the analyzed patients fulfilled the criteria for pacing induced cardiomyopathy (PICM). Improvement in left ventricular ejection fraction (LVEF) and GLS was observed in patients with LVEF <50% at baseline (n = 39): 41.4 ± 9.2% versus 45.6 ± 9.9%, and 12.9 ± 3.6% versus 15.5 ± 3.7%, respectively. In the subgroup with preserved EF (n = 62), LVEF and GLS remained stable at follow-up: 59.3 ± 5.5% versus 60 ± 5.5%, and 19 ± 3.9% versus 19.4 ± 3.8%, respectively.

CONCLUSION

LBBAP prevents PICM in patients with preserved LVEF and improves left ventricle function in subjects with depressed LVEF. LBBAP might be the preferred pacing modality for bradyarrhythmia indications.

Clinical, procedural and lead outcomes associated with different pacing techniques: a network meta-analysis

BACKGROUND

His- Purkinje system pacing (HPSP) techniques have been proposed as alternative to biventricular pacing (BVP) and right ventricular pacing (RVP).

OBJECTIVE

To compare data regarding clinical, procedural and lead outcomes associated with different pacing techniques.

METHODS

An accurate search of online scientific libraries (from inception to May, 12,022) was performed. Thirty-three studies were included in the meta-analysis involving 4386 patients, of whom 1324 receiving RVP, 1032 patients receiving BVP, 1069 patients receiving his-bundle pacing (HBP) and 968 patients receiving left bundle branch pacing (LBBP).

RESULTS

LBBP provided a statistically significant increase in LVEF relative to HBP (0.4473 [0.0584; 0.8361] p = 0.0242) and BVP (0.6733 [0.4734; 0.8732] p < 0.0001) in patients with cardiac resynchronization therapy indication. LBBP and HBP significantly decreased QRS duration as compared to BVP, with largest QRS narrowing obtained by LBBP (-0.4951 [-0.9077; -0.0824] p = 0.0187). As compared to LBBP, HBP was associated with a significant increase of pacing threshold (p = 0.0369) and significant reduction of R-wave amplitude over time (p = 0.027). LBBP was associated with significant reduction in RR of hospitalization for HF (HFH) as compared to both BVP (p = 0.0343) and HBP (p = 0.0476), whereas, as compared to RVP, the risk of lead issues was significantly higher with BVP (p = 0.0424) and HBP (p = 0.0298), but not for LBBP (p = 0.425).

CONCLUSIONS

As compared to other pacing techniques, LBBP significantly improved LVEF, narrowed QRS duration and reduced HFHs, with steadily lower capture thresholds and higher R-wave amplitude, and without increasing lead issues.

Feasibility and safety of both His bundle pacing and left bundle branch area pacing in atrial fibrillation patients: intermediate term follow-up

PURPOSE

His bundle pacing (HBP) improves heart failure (HF) in atrial fibrillation (AF) pacing-dependent patients with a potential for a progressively increased threshold. HBP with right ventricular pacing (RVP) as a backup is always the preferred choice; however, RVP may induce HF. His Purkinje system pacing (HPSP) includes HBP and left bundle branch area pacing (LBBAP). LBBAP maintains left ventricular synchrony but has not been proven to be safe over the long term. We assessed the feasibility and safety of both HBP and LBBAP in AF pacing-dependent patients and compared the parameters of both leads at baseline and at the 6-month follow-up.

METHODS

A total of 16 AF patients in our center, who successfully attempted both HBP and LBBAP, were prospectively enrolled unless only one of these treatment statuses was attained. The electrocardiogram characteristics, leading parameters, echocardiography results, and clinical outcomes were assessed.

RESULTS

Thirteen out of 16 patients achieved both HBP and LBBAP successfully in the same AF pacing-dependent patients. In symptomatic HF patients with preserved left ventricular ejection fraction (LVEF) (n = 10), the left ventricular end-diastolic diameter (LVEDD) was reduced from 51.8 ± 4.4 to 48.3 ± 3.1 mm (p = 0.01) with the use of diuretics, either reduced or stopped (n = 7). During the follow-up, one patient in the group without HF had an increased HBP threshold and developed HF symptoms. His HF symptoms disappeared when switched into LBBAP mode. Another patient in the group with HF got his LVEF elevated by HBP for 3 months by utilizing left bundle branch block(LBBB)correction and continued to increase when switched into LBBAP for another 3 months due to an increased HBP correction threshold. The average unipolar pacing threshold of LBBAP was lower than that of HBP. No perforation or dislodgement occurred in our study.

CONCLUSION

Both HBP and LBBAP could be attempted successfully in the same AF patients when one of the two modes could be adopted and switched according to the clinical feasibility. Compared with HBP, LBBAP yielded better and more stable parameters but showed comparable effects during the 6-month follow-up.

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.

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.

Clinical Outcomes in Conduction System Pacing Compared to Right Ventricular Pacing in Bradycardia

BACKGROUND

Conduction system pacing (CSP) provides more physiological ventricular activation than right ventricular pacing (RVP).

OBJECTIVES

This study evaluated the differences in clinical outcomes in patients receiving CSP and RVP.

METHODS

Consecutive patients with pacemakers implanted for bradycardia from 2016 to 2021 in 2 centers were prospectively followed for the primary composite outcome of heart failure (HF) hospitalizations, upgrade to biventricular pacing, or all-cause mortality, stratified by ventricular pacing burden (Vp) .

RESULTS

Among 860 patients (mean age 74 ± 11 years, 48% female, 48% atrioventricular block), 628 received RVP and 231 received CSP (95 His-bundle pacing, 136 left bundle branch pacing). The primary outcome occurred in 217 (25%) patients, more commonly in patients with RVP than CSP (30% vs 13%, P < 0.001). In multivariable analyses, CSP was independently associated with 47% reduction of the primary outcome (adjusted hazard ratio [AHR]: 0.53; 95% CI: 0.29-0.97; P = 0.04) and HF hospitalization alone (AHR: 0.40; 95% CI: 0.17-0.95; P = 0.04), among only patients with Vp >20%. The incidence of the primary outcome was highest among RVP with Vp >20% and lowest in CSP with Vp >20% (35% vs 10%, P < 0.001). Compared with RVP with Vp >20%, both CSP with Vp >20% (AHR: 0.51; 95% CI: 0.28-0.91; P = 0.02) and all patients with Vp ≤20% (AHR: 0.73; 95% CI: 0.54-0.99; P = 0.04) were independently associated with reduced primary outcome, driven primarily by reductions in HF hospitalizations (P < 0.05). Event-free survival was similar between CSP with Vp >20% and those needing ≤20% Vp.

CONCLUSIONS

CSP significantly reduced adverse clinical outcomes for bradycardic patients requiring ventricular pacing and should be the preferred pacing modality of choice.

Outcomes of conduction system pacing compared to right ventricular pacing as a primary strategy for treating bradyarrhythmia: systematic review and meta-analysis

BACKGROUND

Right ventricular pacing (RVP) may cause electrical and mechanical desynchrony leading to impaired left ventricular ejection fraction (LVEF). We investigated the outcomes of RVP with His bundle pacing (HBP) and left bundle branch pacing (LBBP) for patients requiring a de novo permanent pacemaker (PPM) for bradyarrhythmia.

METHODS AND RESULTS

Systematic review of randomized clinical trials and observational studies comparing HBP or LBP with RVP for de novo PPM implantation between 01 January 2013 and 17 November 2020 was performed. Random and fixed effects meta-analyses of the effect of pacing technology on outcomes were performed. Study outcomes included all-cause mortality, heart failure hospitalization (HFH), LVEF, QRS duration, lead revision, atrial fibrillation, procedure parameters, and pacing metrics. Overall, 9 studies were included (6 observational, 3 randomised). HBP compared with RVP was associated with decreased HFH (risk ratio [RR] 0.68, 95% confidence interval [CI] 0.49-0.94), preservation of LVEF (mean difference [MD] 0.81, 95% CI - 1.23 to 2.85 vs. - 5.72, 95% CI - 7.64 to -3.79), increased procedure duration (MD 15.17 min, 95% CI 11.30-19.04), and increased lead revisions (RR 5.83, 95% CI 2.17-15.70, p = 0.0005). LBBP compared with RVP was associated with shorter paced QRS durations (MD 5.6 ms, 95% CI - 6.4 to 17.6) vs. (51.0 ms, 95% CI 39.2-62.9) and increased procedure duration (MD 37.78 min, 95% CI 20.04-55.51).

CONCLUSION

Of the limited studies published, this meta-analysis found that HBP and LBBP were superior to RVP in maintaining physiological ventricular activation as an initial pacing strategy.

Hemodynamic Doppler echocardiographic evaluation of permanent His bundle and biventricular pacing after AV nodal ablation

placing after atrioventricular (AV) nodal ablation for permanent atrial fibrillation (AF) may include cardiac resynchronization therapy (CRT) with either His bundle pacing (HBP) or biventricular pacing (BVP), or conventional single site right ventricular apical pacing (RVAP). To determine the relationship between pacing method and hemodynamic outcome, we used Doppler echocardiographic methods to evaluate left ventricular (LV) hemodynamics after AV nodal ablation and either HBP, BVP, or RVAP.

Method

20 patients were evaluated > 6 months after AV nodal ablation, 10 each with chronic HBP or BVP, and all with RVAP lead. Doppler echocardiography was used to measure 3 parameters indicative of CRT: 1) LV dP/dt, 2) the LV pre-ejection interval, and 3) myocardial performance index, relative to intra-patient RVAP.

Results

Primary endpoint of LV dP/dt on average improved by > 17% with both HBP and BVP, compared to RVAP. HBP but not BVP, had improvement across all three parameters.

Conclusion

HBP provides LV electromechanical synchrony across multiple echo Doppler parameters. Both HBP and BVP were hemodynamically superior to RVAP following AV nodal ablation.

Early assessment of ventricular synchronization and function after left bundle-branch-area pacing with right bundle-branch block

Aim

To evaluate ventricular synchronization and function in patients with right bundle-branch block after left bundle-branch-area pacing (LBBAP) by echocardiography.

Methods

Forty patients who successfully received LBBAP were selected and divided into the right bundle-branch block group (RBBB group) and the non-RBBB group by pre-operation ECG. Echocardiography and follow-up were performed 1 month after operation. Interventricular synchronization was evaluated by tissue Doppler (TDI), tissue mitral annular displacement (TMAD), and interventricular mechanical delay. The tricuspid annular plane systolic excursion (TAPSE), right ventricular fractional area change (RVFAC), tricuspid annulus sidewall systolic velocity (TV-s’), left ventricular global ventricular longitudinal strain (GLS), right ventricular free wall longitudinal strain (LS-RV), standard deviation of left ventricular 18 segments peak time difference (SDt-L) and standard deviation of right ventricular free wall 3 segments peak time difference (SDt-R) were applied to evaluate intraventricular synchronization and ventricular function.

Results

The difference of displacement peak time of the tricuspid and mitral valves, namely ΔPT_TV-MV measured by TMAD, the difference of systolic time to peak of the tricuspid and mitral valves, namely ΔTs_TV-MV measured by TDI, were statistically different between the two groups (P < 0.05). Compared with the non-RBBB group, there were no statistically significant differences in the GLS, RVFAC, LS-RV, TAPSE, TV-s’, SDt-L, SDt-R (P > 0.05).

Conclusion

Echocardiography technology including two-dimensional speckle tracking imaging (2D-STI), TDI, and TMAD can effectively analyze interventricular synchronization, intraventricular synchronization, and ventricular function. Although the movement of the right ventricular myocardium in the RBBB group was slightly later than that of the left ventricular myocardium after LBBAP, LBBAP could still be applied in RBBB patients with pacing indication.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02818-z.

Left bundle branch potential predicts better electrical synchrony in bradycardia patients receiving left bundle branch pacing

Background

Left bundle branch pacing (LBBP) is a novel physiological pacing technology. We aim to explore the relation between LBB potential (LBB Po) and left ventricular (LV) electrical/mechanical synchrony in bradycardia patients without heart failure (HF) receiving LBBP.

Methods

A total of 62 patients undergoing LBBP were categorized by LBB Po: the LBB Po positive (+) group and the LBB Po negative (−) group. The perioperative electrocardiographic and echocardiography parameters related to cardiac synchrony were analyzed.

Results

There were 42 (67.74%) patients in the LBB Po (+) group and 20 patients in the LBB Po (−) group. Paced QRS duration (113.50 ± 17.65 ms vs. 123.40 ± 13.18 ms, P = 0.031) and stimulus left ventricular activation time (71.76 ± 3.53 ms vs. 74.45 ± 3.12 ms, P = 0.005) were shorter in the LBB Po (+) group than in the LBB Po (−) group. No significant differences in the LV mechanical synchrony (Ts-SD-12, 36.55 ± 19.76 vs. 39.95 ± 16.04, P = 0.505; PSD, 51.14 ± 17.69 vs. 45.65 ± 10.55, P = 0.205) between the two groups. There was not statistically difference in ventricular lead parameters measured intraoperative between the two groups. Compared with the LBB Po (−) group, the LBB Po (+) group showed a dramatically higher total procedure duration time (93.52 ± 9.18 min vs. 86.25 ± 10.54 min, p = 0.007) and fluoroscopy time for ventricle lead implantation (18.95 ± 3.43 min vs. 14.00 ± 3.16 min, p < 0.001).

Conclusions

The appearance of LBB Po may suggest better electrical synchrony during LBBP, but similar in LV mechanical synchrony. However, the total operation duration and fluoroscopy time of ventricular lead implantation in the LBB Po (+) group were longer. Therefore, it may be unnecessary to deliberately recognize the LBB Po when it is difficult to detect LBB Po and meet the LBBP criterion.

Assessing cardiac mechanical dyssynchrony in left bundle branch area pacing and right ventricular septal pacing using myocardial perfusion scintigraphy in the acute phase of pacemaker implantation

INTRODUCTION

Left bundle branch area pacing (LBBAP) has recently been reported to be a new, clinically feasible and safe physiological pacing strategy. The present study aims to investigate the usefulness of LBBAP in reducing mechanical dyssynchrony compared with right ventricular septal pacing (RVSP).

METHODS AND RESULTS

A total of 39 LBBAP patients, 42 RVSP patients, and 93 healthy control participants were retrospectively evaluated. We compared phase analysis- (bandwidth, phase standard deviation [PSD], entropy) and regional wall motion analysis parameters. Wall motion analysis parameters included the time to the end-systolic frame (TES) assessed using single-photon emission computed tomography analysis. The maximum differences between segmental TES (MDTES), the standard deviation of TES (SDTES), and the TES difference between the lateral and septal segments (DTES-LS) were obtained. All phase analysis parameters were significantly smaller in the LBBAP group than in the RVSP group (bandwidth: LBBAP, 74 ± 31° vs. RVSP, 102 ± 59°, p=0.009; PSD: LBBAP, 19 ± 6.7° vs. RVSP, 26 ± 15°, p=0.007; entropy: LBBAP, 0.57 ± 0.07 vs. RVSP, 0.62 ± 0.11 p=0.009). The regional wall motion analysis parameters were also smaller in the LBBAP group than in the RVSP group (MDTES:LBBAP, 17 ± 7.1% vs. RVSP, 25 ± 14%, p=0.004; SDTES :LBBAP, 4.5 ± 1.7% vs. RVSP, 6.0 ± 3.5%, p=0.015; DTES-LS: LBBAP, 4.1 ± 3.4% vs. RVSP, 7.1 ± 5.4%, p=0.004). All phase analysis and wall motion analysis parameters were same in the LBBAP and control groups.

CONCLUSION

LBBAP may reduce mechanical dyssynchrony and achieve greater physiological ventricular activation than RVSP. This article is protected by copyright. All rights reserved.

Generating Evidence to Support the Physiologic Promise of Conduction System Pacing: Status and Update on Conduction System Pacing Trials

Conduction system pacing avoids the potential deleterious effects of right ventricular pacing in patients with bradycardia and provides an alternative approach to cardiac resynchronization therapy. We focus on the available observational and randomized evidence and review studies supporting the safety, feasibility, and physiologic promise of conduction system approaches. We evaluate the randomized data generated from the available clinical trials of conduction system pacing, which have led to the recent inclusion of CSP in international guidelines. The scope for future randomized trials will building on the physiologic promise of conduction system approaches and offering information on clinical end points is explored.

Evaluation of electrophysiological characteristics and ventricular synchrony: An intrapatient-controlled study during His-Purkinje conduction system pacing versus right ventricular pacing

Objectives to Background

To compare electromechanical ventricular synchrony when pacing from different sites, including right ventricular apex pacing (RVAP), right ventricular septum pacing (RVSP), His bundle pacing (HBP), left bundle branch pacing (LBBP), and RVSP during unipolar pacing from the ring electrode of LBBP lead (RVSP_ring) in each patient and evaluate the correlations between electrophysiological characteristics and ventricular synchrony.

Methods

Twenty patients with complete atrioventricular block indicated for dual‐chamber pacemaker implantation were included in the study. Unipolar pacing at different sites, including RVAP, RVSP, HBP, LBBP, and RVSP_ring, was successively performed in each patient. The pacing characteristics and echocardiogram parameters were collected and compared among intrinsic rhythm and pacing at different sites.

Results

Similar to HBP (114.84 ± 18.67 ms), narrower paced QRSd was found in LBBP (116.15 ± 11.60 ms) as compared to RVSP_ring (135.11 ± 13.68 ms), RVSP (141.65 ± 14.26 ms), and RVAP (160.15 ± 19.35 ms) (p < .001). LBBP showed comparable pacing parameters to RVAP or RVSP and was significantly better than HBP, with maintained cardiac function. TS‐12‐SD was significantly improved in LBBP (41.80 ± 20.97 ms) than RVAP (69.70 ± 32.42 ms, p = .003) and RVSP (63.30.56 ± 32.53 ms, p = .018) but similar to HBP (51.50 ± 25.67 ms, p = .283) or RVSP_ring (57.80 ± 25.65 ms, p = .198). Among these pacing strategies, negative values of interventricular mechanical delay (IVMD) were only identified in LBBP (−19.25 ± 18.43 ms), significantly different from RVAP (35.00 ± 30.72 ms), RVSP (22.85 ± 22.05 ms), HBP (5.20 ± 18.64 ms), and RVSP_ring (16.00 ± 26.76 ms (all p < .05). Using Pearson's analysis, Sti‐LVAT was positively correlated with QRS duration, IVMD, TS‐12‐SD, LVEDV, and LVESV, while a negative relationship could be observed for left ventricular ejection fraction.

Conclusions

His‐Purkinje conduction system pacing (HPCSP) achieved better electrical and mechanical synchrony than conventional RV pacing. For interventricular synchrony, only LBBP initiated earlier LV activation than RV, in accordance with the right bundle branch block (RBBB) pattern of paced QRS during LBBP. Sti‐LVAT might be a good parameter correlating with LV systolic function and mechanical synchrony.

Clinical Outcomes of Left Bundle Branch Area Pacing in Comparison with Right Ventricular Septal Pacing in Patients with High Ventricular Pacing Ratio ≥40%

Background

Methods

Results

Conclusion

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.

Comparative effects of left bundle branch area pacing, His bundle pacing, biventricular pacing in patients requiring cardiac resynchronization therapy: A network meta-analysis

Background

The comparative effects of different types of cardiac resynchronization therapy (CRT) delivered by biventricular pacing (BVP), His bundle pacing (HBP), and left bundle branch area pacing (LBBAP) remain inconclusive.

Hypothesis

HBP and LBBAP may be advantageous over BVP for CRT.

Methods

PubMed, Embase, Web of Science, and the Cochrane Library were systematically searched for studies that reported the effects after BVP, HBP, and LBBAP for CRT. The effects between groups were compared by a frequentist random‐effects network meta‐analysis (NMA), by which the mean differences (MDs) and 95% confidence intervals (CIs) were calculated.

Results

Six articles involving 389 patients remained for the final meta‐analysis. The mean follow‐up of these studies was 8.03 ± 3.15 months. LBBAP resulted in a greater improvement in LVEF% (MD = 7.17, 95% CI = 4.31 to 10.04), followed by HBP (MD = 4.06, 95% CI = 1.09 to 7.03) compared with BVP. HBP resulted in a narrower QRS duration (MD = 31.58 ms, 95% CI = 12.75 to 50.40), followed by LBBAP (MD = 27.40 ms, 95% CI = 10.81 to 43.99) compared with BVP. No significant differences of changes in LVEF improvement and QRS narrowing were observed between LBBAP and HBP. The pacing threshold of LBBAP was significantly lower than those of BVP and HBP.

Conclusion

The NMA first found that LBBAP and HBP resulted in a greater LVEF improvement and a narrower QRS duration compared with BVP. Additionally, LBBAP resulted in similar clinical outcomes but with lower pacing thresholds, and may therefore offer advantages than does HBP for CRT.

Septal Flash Correction with His-Purkinje Pacing Predicts Echocardiographic Response in Resynchronization Therapy

Background

His‐Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to Cardiac Resynchronization Therapy (CRT); however, predictors of echocardiographic response have not been described in this population. Septal flash (SF), a fast contraction and relaxation of the septum, is a marker of intraventricular dyssynchrony.

Methods

The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. This retrospective analysis of prospectively collected data included 30 patients. Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6‐month follow‐up. Echocardiographic response was defined as increase in five points in LVEF.

Results

HPCSP shortened QRS duration by 48 ± 21 ms and SF was significantly decreased (baseline 3.6 ± 2.2 mm vs. HPCSP 1.5 ± 1.5 mm p < .0001). At 6‐month follow‐up, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r = .61, p = .004). A correction of ≥1.5 mm (baseline SF – paced SF) had a sensitivity of 81% and 80% specificity to predict echocardiographic response (area under the curve 0.856, p = .019).

Conclusion

HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6‐month follow‐up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6‐month follow‐up.

Left bundle branch pacing: An evolving site for physiological pacing

For patients with symptomatic bradyarrhythmia, cardiac pacing is the only appropriate treatment option. Electrical and mechanical dyssynchrony caused by traditional right ventricular apical pacing leads to left ventricular dysfunction and atrial arrhythmias. Physiological pacing stimulates natural cardiac conduction, resulting in synchronized ventricular contraction. Even if His bundle pacing (HBP) is an ideal physiological pacing modality, it is technically not always feasible because of high capture thresholds, disease in the distal His bundle, and follow-up troubleshooting issues. Left bundle branch pacing (LBBP) has been proposed as a viable alternative to HBP since it provides lead stability, a low and stable pacing threshold, and correction of distal conduction system disease.

Physiology and Practicality of Left Ventricular Septal Pacing

Left ventricular septal pacing (LVSP) and left bundle branch pacing (LBBP) have been introduced to maintain or correct interventricular and intraventricular (dys)synchrony. LVSP is hypothesised to produce a fairly physiological sequence of activation, since in the left ventricle (LV) the working myocardium is activated first at the LV endocardium in the low septal and anterior free-wall regions. Animal studies as well as patient studies have demonstrated that LV function is maintained during LVSP at levels comparable to sinus rhythm with normal conduction. Left ventricular activation is more synchronous during LBBP than LVSP, but LBBP produces a higher level of intraventricular dyssynchrony compared to LVSP. While LVSP is fairly straightforward to perform, targeting the left bundle branch area may be more challenging. Long-term effects of LVSP and LBBP are yet to be determined. This review focuses on the physiology and practicality of LVSP and provides a guide for permanent LVSP implantation.

Pacing of Specialized Conduction System

Right ventricular pacing for bradycardia remains the mainstay of pacing therapy. Chronic right ventricular pacing may lead to pacing-induced cardiomyopathy. We focus on the anatomy of the conduction system and the clinical feasibility of pacing the His bundle and/or left bundle conduction system. We review the hemodynamics of conduction system pacing, the techniques to capture the conduction system and the electrocardiogram and pacing definitions of conduction system capture. Clinical studies of conduction system pacing in the setting of atrioventricular block and after AV junction ablation are reviewed and the evolving role of conduction system pacing is compared with biventricular pacing.

His-Purkinje conduction system pacing: A systematic review and network meta-analysis in bradycardia and conduction disorders

BACKGROUND

His-Purkinje conduction system pacing (HPCSP) has emerged as an effective alternative to overcome the limitations of right ventricular pacing (RVP) via physiological left ventricular activation, but there remains a paucity of comparative information for His bundle pacing (HBP) and left bundle branch pacing (LBBP).

METHODS

A Bayesian random-effects network analysis was conducted to compare the relative effects of HBP, LBBP, and RVP in patients with bradycardia and conduction disorders. PubMed, Embase, Cochrane Library, and Web of Science were systematically searched from database inception until September 21, 2021.

RESULTS

Twenty-eight studies involving 4160 patients were included in this meta-analysis. LBBP significantly improved success rate, pacing threshold, pacing impedance, and R-wave amplitude compared with HBP. LBBP also demonstrated a nonsignificant trend towards superior outcomes of lead complications, heart failure hospitalization, atrial fibrillation, and all-cause death. However, HBP was associated with significantly shorter paced QRS duration relative to LBBP. Despite higher success rates, shorter procedure/fluoroscopy duration, and fewer lead complications, patients receiving RVP were more likely to experience reduced left ventricular ejection fraction, longer paced QRS duration, and higher rates of heart failure hospitalization than those receiving HPCSP. No statistical differences were observed in the remaining outcome measures.

CONCLUSIONS

This network meta-analysis demonstrates the efficacy and safety of HPCSP for the treatment of bradycardia and conduction disorders, with differences in pacing parameters, electrophysiology characteristics, and clinical outcomes between HBP and LBBP. Larger-scale, long-term comparative studies are warranted for further verification.

Left Bundle Branch Area Pacing: Implant Technique, Definitions, Outcomes, and Complications

PURPOSE OF REVIEW

Conduction system pacing (CSP) has emerged during the last few years as the cornerstone of physiological pacing. Two different CSP modalities have been described so far: His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). This review will be focused on the description of LBBAP technique, definitions, outcomes, and complications.

RECENT FINDINGS

Large observational studies have demonstrated the safety and feasibility of LBBAP in different scenarios. LBBAP has been associated with excellent pacing electrical parameters (pacing threshold and R wave sensing) and low complication rates including lead revision < 1%. In patients with cardiac resynchronization therapy (CRT) indication, LBBAP has shown significant improvement of functional class and left ventricular ejection fraction during short-term follow-up. LBBAP is a relatively new CSP modality showing excellent results for patients with conventional bradycardia pacing indications and promising expectations about its potential role for CRT.

Feasibility and Safety of Left Bundle Branch Pacing for Advance Aged Patients: A Multicenter Comparative Study

Background: Left bundle branch pacing (LBBP) has been shown to be a safe and effective means to achieve physiological pacing. However, elderly patients have increased risks from invasive procedures and the risk of LBBP in elderly patients is not known. We aimed to investigate the safety and efficacy of LBBP in elderly patients >80 years of age.

Methods: From December 2017 to June 2019, 346 consecutive patients with symptomatic bradycardia, 184 patients under 80 years of age and 162 over 80 years, were included and underwent LBBP. The safety and prognosis of LBBP were comparatively evaluated by measured pacing parameters, periprocedural complications, and follow-up clinical events.

Results: Compared with the younger, the elderly group had worse baseline cardiac and renal function. LBBP was achieved successfully in both groups with comparable fluoroscopic time and paced QRS duration (110.0 [102.0, 118.0] ms for the young vs. 110.0 [100.0, 120.0] ms for the elderly, P = 0.874). Through a follow-up of 20.0 ± 6.1 months, pacing parameters were stable while higher threshold and impedance were observed in the elderly group. In the evaluation of safety, overall procedure-related complication rates were comparable (4.4 vs. 3.8%, young vs. elderly). For prognosis, similar rates of major adverse cardiocerebrovascular events (7.1 vs. 11.9%, young vs. elderly) were observed.

Conclusions: Compared to younger patients, LBBP could achieve physiological pacing in patients over 80 with comparable midterm safety and prognosis. Long-term safety and benefits of LBBP, however, necessitate further evaluation.

Safety and feasibility of left bundle branch area pacing following valvular interventions: Multicenter study

OBJECTIVES

To evaluate the safety and feasibility of left bundle branch area pacing (LBBAP) in patients with valvular interventions.

METHODS

Eighty-four patients were included in this study. All patients underwent recent surgical or percutaneous valvular interventions. LBBAP was attempted in all patients. Implant success rates, peri- and postprocedure electrocardiogram, pacing parameters, and complications were assessed at implant, and during follow-up.

RESULTS

LBBAP implantation was successful in 80/84 (95%) patients. Mean age was 74.1 ± 13.8 years and 56% patients were male. Prior valvular replacements included: percutaneous aortic (26), surgical aortic (36), combined surgical aortic plus mitral (6), MVR (10), tricuspid (1), and pulmonic (1). Average LVEF was 52.6 ± 11%. Majority of patients underwent LBBAP due to atrioventricular block (76%) and sinus node disease (13%). Total procedure duration was 74.1 ± 12.5 min and fluoroscopic duration was 9.7 ± 6.8 min. Pacing parameters were stable during follow-up period of 10.0 ± 6.3 months. Pacing QRS duration was significantly narrower than baseline QRS duration (131.5 ± 31.4 ms vs. 114.3 ± 13.7 ms, p < .001, respectively). No acute complications were observed. Mean follow-up was 10.0 ± 6.3 months (median: 8.4 months, min: 1 and max: 24 months). During follow-up, there were three device infections and two patients had loss of LBBA capture within 1 month of implant.

CONCLUSIONS

LBBAP is a feasible and safe pacing modality in patients with prior interventions for valvular heart disease.

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.

Clinical Outcomes in Patients With Left Bundle Branch Area Pacing vs. Right Ventricular Pacing for Atrioventricular Block

Background: Left bundle branch area pacing (LBBAP) is a novel pacing modality with stable pacing parameters and a narrow-paced QRS duration. We compared heart failure (HF) hospitalization events and echocardiographic measures between LBBAP and right ventricular pacing (RVP) in patients with atrioventricular block (AVB).

Methods and Results: This multicenter observational study prospectively recruited consecutive AVB patients requiring ventricular pacing in five centers if they received LBBAP or RVP and had left ventricular ejection fraction (LVEF) >50%. Data on electrocardiogram, pacing parameters, echocardiographic measurements, device complications, and clinical outcomes were collected at baseline and during follow-up. The primary outcome was first episode hospitalization for HF or upgrade to biventricular pacing. LBBAP was successful in 235 of 246 patients (95.5%), while 120 patients received RVP. During a mean of 11.4 ± 2.7 months of follow-up, the ventricular pacing burden was comparable (83.9 ± 35.1 vs. 85.7 ± 30.0%), while the mean LVEF differed significantly (62.6 ± 4.6 vs. 57.8 ± 11.4%) between the LBBAP and RVP groups. Patients with LBBAP had significantly lower occurrences of HF hospitalization and upgrading to biventricular pacing than patients with RVP (2.6 vs. 10.8%, P <0.001), and differences in primary outcome between LBBAP and RVP were mainly observed in patients with ventricular pacing >40% or with baseline LVEF <60%. The primary outcome was independently associated with LBBAP (adjusted HR 0.14, 95% CI: 0.04–0.55), previous myocardial infarction (adjusted HR 6.82, 95% CI: 1.23–37.5), and baseline LVEF (adjusted HR 0.91, 95% CI: 0.86–0.96).

Conclusion: Permanent LBBAP might reduce the risk of HF hospitalization or upgrade to biventricular pacing compared with RVP in AVB patients requiring a high burden of ventricular pacing.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03851315; URL: http://www.chictr.org.cn; Unique Identifier: ChiCTR2100043296.

A network meta-analysis and systematic review of change in QRS duration after left bundle branch pacing, His bundle pacing, biventricular pacing, or right ventricular pacing in patients requiring permanent pacemaker

Cardiac dyssynchrony is the proposed mechanism for pacemaker-induced cardiomyopathy, which can be prevented by biventricular pacing. Left bundle branch pacing and His bundle pacing are novel interventions that imitate the natural conduction of the heart with, theoretically, less interventricular dyssynchrony. One of the surrogate markers of interventricular synchrony is QRS duration. Our study aimed to compare the change of QRS duration before and after implantation between types of cardiac implantable electronic devices (CIEDs): left bundle branch pacing versus His bundle pacing versus biventricular pacing and conventional right ventricular pacing. A literature search for studies that reported an interval change of QRS duration after CIED implantation was conducted utilizing the MEDLINE, EMBASE, and Cochrane databases. All relevant works from database inception through November 2020 were included in this analysis. A random-effects model, Bayesian network meta-analysis was used to analyze QRS duration changes (eg, electrical cardiac synchronization) across different CIED implantations. The mean study sample size, from 14 included studies, was 185 subjects. The search found 707 articles. After exclusions, 14 articles remained with 2,054 patients. The His bundle pacing intervention resulted in the most dramatic decline in QRS duration (mean difference, - 53 ms; 95% CI - 67, - 39), followed by left bundle branch pacing (mean difference, - 46 ms; 95% CI - 60, - 33), and biventricular pacing (mean difference, - 19 ms; 95% CI - 37, - 1.8), when compared to conventional right ventricle apical pacing. When compared between LBBP and HBP, showed no statistically significant wider QRS duration in LBBP with mean different 6.5 ms. (95% CI - 6.7, 21). Our network meta-analysis found that physiologic pacing has the greatest effect on QRS duration after implantation. Thus, HBP and LBBP showed no significant difference between QRS duration after implantation. Physiologic pacing interventions result in improved electrocardiography markers of cardiac synchrony, narrower QRS duration, and might lower electromechanical dyssynchrony.

Safety and efficacy of His-bundle pacing/left bundle branch area pacing versus right ventricular pacing: a systematic review and meta-analysis

BACKGROUND

Recent studies have demonstrated that right ventricular pacing (RVP) has deleterious effects on non-synchronized ventricular contraction, while His-bundle pacing (HBP) or left bundle branch area pacing (LBBaP) contribute to improvements in patients' mid- and long-term outcomes. This meta-analysis aimed to compare the safety and efficacy of physiologic pacing (HBP/LBBaP) versus those of RVP.

METHODS

A systematic search of PubMed, Cochrane Library, and Embase was conducted for studies that compared the effects of physiologic pacing and RVP. All eligible studies were published before January 1, 2021 and were conducted in humans. STATA software version 15.0 was used for all the data analyses.

RESULTS

Twenty articles (n = 2787 patients) were included in this meta-analysis. Compared to RVP, physiologic pacing was associated with a significantly shorter QRS duration and better cardiac function. Physiologic pacing was also correlated with lower rates of mitral regurgitation, pacing-induced cardiomyopathy, death, heart failure hospitalization, and atrial fibrillation, although the above results were not statistically significant. In addition, RVP led to the achievement of higher success rates than physiologic pacing, a shorter fluoroscopic time and mean procedure duration, a lower pacing threshold: the results were statistically significant. Compared with HBP, LBBaP appeared to have some advantages in R wave amplitudes, pacing threshold, fluoroscopic time, procedure time, and success rate, with statistically significant differences. Whereas HBP was associated with fewer surgical complications and shorter QRS duration, the results were not statistically significant.

CONCLUSION

Physiologic pacing (HBP/LBBaP) might be a better strategy than RVP and improve long-term clinical outcomes like cardiac function. Although LBBaP appears to have some advantages over HBP, the long-term benefits are still controversial. More large-scale randomized clinical trials are needed for further verification.

Procedure-Related Complications of Left Bundle Branch Pacing: A Single-Center Experience

Background: Although left bundle branch pacing (LBBP) has emerged as a novel physiological pacing strategy with a low and stable threshold, its safety has not been well-documented. In the present study, we included all the patients with procedure-related complications at our centre to estimate these LBBP cases with unique complications. Methods: We enrolled 612 consecutive patients who received the procedure in Zhongshan Hospital, Fudan University, between January 2018 and July 2020. Regular follow-ups were conducted (at 1, 3, and 6 months in the first year and every 6-12 months from the second year), and the clinical data of the patients with complications were collected and analyzed. Results: With a mean follow-up period of 12.32 ± 5.21 months, procedure-related complications were observed in 10 patients (1.63%) that included two postoperative septum perforations (2/612, 0.33%), two postoperative lead dislodgements (2/612, 0.33%), four intraoperative septum injuries (4/612, 0.65%), and two intraoperative lead fractures (2/612, 0.33%). Pacing parameters were stable during follow-up, and no major complications were observed after lead repositioning in the cases of septum perforation and lead dislodgement. Conclusion: The incidence of procedure-related complications for LBBP, namely postoperative septum perforation, postoperative lead dislodgement, intraoperative septum injury, and intraoperative lead fracture, were low. No adverse clinical outcomes were demonstrated after successful repositioning of the lead and appropriate treatment.

Clinical outcomes of left bundle branch pacing compared to right ventricular apical pacing in patients with atrioventricular block

Background

Left bundle branch pacing (LBBP) can produce near normalization of QRS duration. This has recently emerged as alternative technique to right ventricular pacing and His bundle pacing.

Hypothesis

The purpose of this study is to evaluate clinical outcomes of LBBP compared to right ventricular apical pacing (RVAP).

Methods

A total of 70 AVB patients with indications for ventricular pacing were retrospectively studied. LBBP was attempted in 33 patients, classified as LBBP group. The other patients were classified as RVAP group. Pacing parameters, electrocardiogram and echocardiogram characteristics, heart failure hospitalization (HFH), and atrial fibrillation (AF) were evaluated perioperatively and at follow‐ups. Patients were followed in the device clinic for a minimum of 12 months and up to 24 months at a 3–6 monthly interval.

Results

LBBP was successful in 29 of 33(87.9%) patients while all 37 of the remaining patients successfully underwent RVAP. Paced QRS duration was significantly narrower in the LBBP group compare to RVAP(110.75 ± 6.77 ms vs. 154.29 ± 6.96 ms, p = .000) at implantation, and the difference persisted during follow‐ups. Pacing thresholds (at implantation: 0.68 ± 0.22 V in the LBBP group and 0.73 ± 0.23 V in the RVAP group, p = .620) remained low and stable during follow‐ups. The cardiac function in the LBBP group remained stable during follow‐ups (LVEF%:55.08 ± 4.32 pre‐operation and 54.17 ± 4.34 at the end of follow‐up, p = .609), and better than RVAP group (LVEF%: 54.17 ± 4.34 vs. 50.14 ± 2.14, p = .005). Less HFH was observed in the LBBP group (2/29,6.89%) compared to RVAP group (10/37,27.03%).

Conclusions

The present investigation demonstrates the safety and feasibility of LBBP that produces narrower paced QRS duration than RVAP. LBBP is associated with reduction in the occurrence of pacing‐induced left ventricular dysfunction and HFH compared to RVAP in patients requiring permanent pacemakers.

Comparing Ventricular Synchrony in Left Bundle Branch and Left Ventricular Septal Pacing in Pacemaker Patients

Background: Left bundle branch area pacing (LBBAP) has recently been introduced as a novel physiological pacing strategy. Within LBBAP, distinction is made between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP, no left bundle capture). Objective: To investigate acute electrophysiological effects of LBBP and LVSP as compared to intrinsic ventricular conduction. Methods: Fifty patients with normal cardiac function and pacemaker indication for bradycardia underwent LBBAP. Electrocardiography (ECG) characteristics were evaluated during pacing at various depths within the septum: starting at the right ventricular (RV) side of the septum: the last position with QS morphology, the first position with r’ morphology, LVSP and—in patients where left bundle branch (LBB) capture was achieved—LBBP. From the ECG’s QRS duration and QRS morphology in lead V1, the stimulus- left ventricular activation time left ventricular activation time (LVAT) interval were measured. After conversion of the ECG into vectorcardiogram (VCG) (Kors conversion matrix), QRS area and QRS vector in transverse plane (Azimuth) were determined. Results: QRS area significantly decreased from 82 ± 29 µVs during RV septal pacing (RVSP) to 46 ± 12 µVs during LVSP. In the subgroup where LBB capture was achieved (n = 31), QRS area significantly decreased from 46 ± 17 µVs during LVSP to 38 ± 15 µVs during LBBP, while LVAT was not significantly different between LVSP and LBBP. In patients with normal ventricular activation and narrow QRS, QRS area during LBBP was not significantly different from that during intrinsic activation (37 ± 16 vs. 35 ± 19 µVs, respectively). The Azimuth significantly changed from RVSP (−46 ± 33°) to LVSP (19 ± 16°) and LBBP (−22 ± 14°). The Azimuth during both LVSP and LBBP were not significantly different from normal ventricular activation. QRS area and LVAT correlated moderately (Spearman’s R = 0.58). Conclusions: ECG and VCG indices demonstrate that both LVSP and LBBP improve ventricular dyssynchrony considerably as compared to RVSP, to values close to normal ventricular activation. LBBP seems to result in a small, but significant, improvement in ventricular synchrony as compared to LVSP.

Left bundle branch pacing for cardiac resynchronization therapy: A systematic literature review and meta-analysis

BACKGROUND

Left bundle branch pacing (LBBP) recently has been suggested as an alternative modality to deliver cardiac resynchronization therapy (CRT). Data on LBBP for CRT are limited to small sample reports, and clinical benefits and risks have not been systematically assessed. We sought to systematically examine published studies of LBBP for CRT and quantify the feasibility and efficacy of the therapy.

METHODS

Cochrane Library, PubMed, Web of Science, and Embase databases were searched from inception to September 30, 2020 to identify relevant studies evaluating LBBP in patients for CRT. Clinical outcomes of interest included implant success rate, QRS duration (QRSd), pacing threshold, left ventricular (LV) function at baseline and follow-up, heart failure-related hospitalization, and mortality. Data were extracted and summarized.

RESULTS

A total of six studies (two single-arm studies and four comparative studies) involving 174 patients were included. The results showed that the average age of patients was 64.9 years and all were implanted for CRT. The procedural success rate was only reported in two studies (97% and 81.1%, respectively). LBBP resulted in a narrow of mean QRSd from 172.7 ± 4.8 to 115.1 ± 7.6 ms. LV function, including LV ejection fraction and LV end-diastolic dimension improved at follow-up. During a mean follow-up of 8.1 months, 1.3% of patients experienced heart failure-related hospitalization and no patients died.

CONCLUSION

LBBP is a feasible strategy with significant efficacy and safety for CRT candidates.

Left Bundle Branch Pacing: A New Alternative to Resynchronization Therapy in the 2020 Pacing Armamentarium

His bundle pacing was developed while seeking a physiological alternative to biventricular cardiac resynchronization therapy. However, His bundle pacing may not be adequate in all patients. In this scenario, left bundle branch pacing has arisen as a new cardiac resynchronization therapy modality to correct left bundle branch block and restore ventricular synchrony. (Level of Difficulty: Intermediate.).

LBBAP in patients with normal intrinsic QRS duration: Electrical and mechanical characteristics

BACKGROUND

Left bundle branch area pacing (LBBAP) is an innovative pacing technology, which needs further study.

METHODS

Seventy LBBAP patients with intrinsic QRS duration (QRSd) less than 120 ms were consecutively enrolled in our center. According to whether the left bundle branch potential (LBBp) was recorded or not, the patients were divided into the potential positive group (LBBAP+) and the potential negative group (LBBAP-). Electrocardiographic and echocardiographic parameters were used to evaluate electrical and mechanical characteristics. Lead parameters and complications were followed-up.

RESULTS

There were 52 patients in LBBAP+ and 18 patients in LBBAP-. The QRSd and the left ventricular activation time (LVAT) were wider after LBBAP. QRSd showed no significant difference between LBBAP+ and LBBAP-. LVAT was significantly shorter in LBBAP+ than in LBBAP-. Frontal QRS axis shifted leftward and the V1 morphologies changed after LBBAP. QRS axis and V1 morphologies showed no significant differences between two groups. Paced R-wave transition moved forward compared with intrinsic R-wave transition in both groups. Peak systolic strain of left ventricle (LVPSS) increased, and peak systolic dispersion of left ventricle (LVPSD) did not change significantly after LBBAP. Systolic and diastolic function as well as mechanical synchronism had no significant differences between two groups. LBBAP had great pacing parameters.

CONCLUSION

LBBAP changes electrical and mechanical characteristics and has good safety in patients with normal intrinsic QRSd. LBBAP+ and LBBAP- show no significant differences in mechanical synchronization and interventricular electrical synchronization. The LBBAP+ shows better left ventricular electrical synchronicity.