His Bundle Pacing Research Articles

Electrophysiological Characteristics and Mechanism of His-Bundle Pacing Guided by Electrocardiograms in Uninterrupted Real-Time Monitoring Technique.

His-bundle pacing (HBP) is a pacing mode that provides near-physiological pacing and has more advantages over standard right ventricle (RV) septum pacing in positive clinical results. However, traditional HBP cannot accurately and stably place the lead tip into the His-Purkinje system. Hence, this study aimed to establish a novel strategy for HBP to strike a balancebetween an excellent pacing threshold and minor injuries to the conduction system. HBP, using continuous and real-time monitoring of unipolar His-bundle (HB) electrograms along with electrocardiograms, was performed in 29 consecutive atrial fibrillation patients. We analyzed the unipolar HB intracardiac electrogram (EGM) and electrophysiological characteristics during HBP using John Jiang's connecting cable and an electrophysiology recording system. All patients were followed up for 12 months. Of the 29 patients, 28 (96.55%) successfully received HBP. Twenty-one (75%) patients were confirmed to have the negative deflection of His potential with a negative amplitude of ≥ 0.1mV in HB EGM. The subgroup with a deep negative deflection was recorded with an HBP threshold (0.71 ± 0.41V), significantly lower than those thresholds with no deep negative deflection (1.83 ± 0.76V) (p < 0.05). The selective HBP rate was significantly different between the two groups: 20 (95.24%) in the deep negative deflection group and three (42.86%) in thenon-deep negative deflection group (p < 0.05); five (17.24%) patients presented right bundle branch block (RBBB) during the lead placement. This study supports the safety and feasibility of using an uninterrupted real-time monitoring technique for HBP. An uninterrupted real-time monitoring technique can guide theaccurate placement of the HB lead and may provide abalancebetween anexcellent pacing threshold and minor injury to the conduction system.

Extraction of old His bundle pacing leads and coronary sinus leads - an analysis of 3897 lead extraction procedures including 27 His and 253 coronary sinus lead removals

Abstract Background The lumen-less the Medtronic 3830 lead is most popular for His bundle pacing (HBP) and experience with such lead extraction are very limited especially for leads older than 4 years. Methods Analysis of 3898 transvenous lead extraction (TLE) procedures (including 27 HBP and 253 LVP lead extraction) was performed. Results The HBP was used usually in the CRT-D system (72.4%) and EF and NYHA class were better than patients with LVP extracted leads. Age of extracted HBP or LVP lead did not differ significantly (54.5 vs 50.2 months). Extraction of "old" HBP leads extraction was longer than in case of "young HBP leads (8,6 and 3.8 min). Mechanical dilatation was necessary in 63 and 100% extracted HBP leads. Unexpected procedure difficulties appeared (14,3%) and utility of second line / advanced tools had been utilised (28,6%) only when "old" HBP lead were extracted. Difficulties in extracting HBP leads were comparable to those encountered in the extraction of LVP leads of similar age. There was no extracted 3830 extracted lead break and no major complication, necessity of rescue cardiac surgery and procedure related death when HBP and LVP leads were extracted. The length of the FU period for those still alive patients was shorter for patients with removed leads for HBP as this technique was introduced significantly later than LVP. However, the 1-month mortality rate of patients with LVP lead removed is higher than in the HBP and control groups. Conclusions 1. HBP most frequently is utilised in the CRT-D system for resynchronisation of failing heart (72.4%) 2. Extraction of HBP leads is performed most frequently due to non-infective indications (59,3%) and most often because of lead dysfunction (33,3%). 3. Extraction of "old" (&amp;gt;40 mth) HBP leads is twice longer than younger ones (3.8 and 8,6 min) and mechanical dilatation is necessary frequently. 4. Extraction of "old" (&amp;gt;40 mth) HBP leads is more difficult than younger ones due to appearance unexpected procedure difficulties (14,3%) and necessity utility of second line / advanced tools (28,6%) but it does not entail the risk of major complications and procedure related death. 5. Difficulties in extracting HBP leads comparable to those encountered in the extraction of LVP leads of similar age. 6. Survival after HBP and LVP lead extraction was comparable, but shorter than after removal of other leads.

Conduction-System pacing Italian Network Group (C-SING): insights from a Nationwide Multicenter Observational Study

Abstract Background/Introduction Conduction system pacing (CSP), encompassing His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), has gained prominence in treating bradycardia and heart failure in recent years. Despite its increasing utilization, data on real-world adoption of CSP are limited. Purpose The C-SING study aimed at assessing patient characteristics, implant success, procedural details, and safety of CSP when performed in routine clinical practice. Methods Periprocedural data from 27 experienced CSP centers across Italy were collected on patients undergoing CSP implantation for various indications between January 2021 and January 2024. Results The study comprised 1,317 patients (median age 78 years [interquartile range, 71-83], male 66.2%). Leading indications included atrioventricular (AV) block (40.8%), sinus node dysfunction (12.1%), atrial fibrillation with bradycardia (9.7%), AV node ablation (9.5%), and heart failure (12.5%). Pacemakers were implanted in 77.3% of patients, cardiac resynchronization devices in 21.7%, and implantable cardioverter-defibrillators in 1.0%. Stylet-driven and lumenless CSP leads were utilized in 64.7% and 35.3% of procedures, respectively. Final 12-lead ECG assessment revealed LBBAP capture in 88.7% patients, HBP in 8.4% (selective 4.2%, non-selective 4.2%), and no CSP capture in 3.0%, resulting in a 97.0% CSP lead implantation success rate. In patients with LBBAP, predominant capture types were left bundle branch pacing (19.6%), left posterior fascicular pacing (19.2%), and left septal fascicular pacing (14.8%). Comparing HBP to LBBAP, the latter showed shorter procedural time (60 minutes [45-80] vs. 70 minutes [60-95], p=0.003), but similar fluoroscopy time (6.0 minutes [3.3-10.8] vs. 6.1 minutes [4-10], p=0.735). Paced QRS duration was longer in LBBAP (118 ms [105-130]) compared to HBP (110 ms [101-122], p&amp;lt;0.001). LBBAP showed lower capture thresholds (0.6 V [0.5-0.9] @0.4 ms vs. 0.8 V [0.5-1.5] @1.0 ms, p&amp;lt;0.001) and higher R-wave sensing (10.7 mV [8-16] vs. 4.5 mV [2.4-9.9], p&amp;lt;0.001). The rate of periprocedural complications was higher in patients with LBBAP than HBP (7.3% vs. 1.8%, p=0.03), with the most frequent events being intraprocedural perforation into the left ventricular cavity during lead screwing (2.6%) and CSP lead dislodgment before hospital discharge (1.4%). These occurrences necessitated lead repositioning without additional complications. Conclusion CSP demonstrated feasibility as a primary pacing strategy for various indications in a real-world, multicenter setting. LBBAP, more frequently used than HBP, exhibited shorter procedural time and superior acute electrical parameters. LBBAP revealed a higher rate of minor procedural complications than HBP. Further investigations, supported by additional long-term outcome data, are essential to comprehensively assess CSP performance.

Larger QRS but better hemodynamic function after high output His bundle pacing in patients with heart failure and narrow QRS. A paradox or a new concept?

Abstract Background QRS duration is an important factor in determining Cardiac Resynchronisation Therapy (CRT) response and a useful surrogate for electromechanical dyssynchrony. However, we don’t have studies confirming this concept in conduction system pacing. Purpose We performed His Bundle Pacing (HBP) with high output (3.5V/1msec) in HF patients with dilated or ischemic cardiomyopathy and narrow QRS to evaluate hemodynamic benefit independent of the QRS duration or AV delay shortening. Methods 14 patients with dilated (7 patients) or ischemic (7 patients) cardiomyopathy (EF&amp;lt;35%) and narrow QRS (&amp;lt;120ms) were referred for implantation of a defibrillator. We implanted an ICD- HBP system, and we collected clinical, echocardiographic, and electrocardiographic data. Results We obtained HBP in all 14 patients successfully. PQ after implantation was shorter from 172±48 to 143±16 (P=0.048) so as to pace the ventricle. Baseline QRS duration increased after pacing from 110±15 to 123±16ms (P=0.008) as measured by ECG analyzer. Despite this increase in QRS duration basal mean EF increased from 30±4% to 46±10% (P&amp;lt;0.001) after a median follow-up of 17 months. Left ventricular end-diastolic diameter and left ventricular end-diastolic volume decreased from 62±5 to 57±5mm (P=0.013) and from 195±69 to 126±27ml (P&amp;lt;0.001), respectively. Left ventricular end-systolic volume decreased from 139±58 to 69±27 (P&amp;lt;0.001). TAPSE increased from 19±4 to 27±4. NYHA class decreased by one class in every patient after only one month. HBP threshold was 1.05V±0.7/1msec and raised to 1.33±0.93/1msec (due mainly to 2 patients with very high threshold). The impedance was 588±109 and decreased to 484±69 Ohms. R-wave at implant was 3.2±1.8mV. In 2 out of 14 patients, threshold increased but was still less than 3.5V/1msec. Conclusions HBP in HF patients with dilated or ischemic cardiomyopathy and narrow QRS improves hemodynamic function in right and left ventricle and decreases NYHA class. This benefit appears to be produced by a higher stimulation output despite a larger QRS after pacing. We exclude that a very short AV delay could be favorable, by measuring acute EF changes only after increasing the pacing output without AV delay modifications. To our knowledge these are the first cases of beneficial HBP in HF patients with narrow QRS. Interestingly, larger QRS corresponds to higher EF in patients with high output HIs Bundle Pacing.

A comparative analysis of conduction system pacing and biventricular pacing in patients undergoing atrioventricular node ablation: a systematic review and meta-analysis

Abstract Background Atrioventricular node ablation (AVNA) with concomitant permanent pacemaker implantation is a well-established management strategy for patients with atrial fibrillation demonstrating refractory and uncontrolled ventricular rates. Conduction system pacing (CSP) utilising His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), has emerged as an alternative to conventional pacing (CP) (including right ventricular pacing (RVP) and biventricular pacing (BVP). The aims and objectives of this systematic review and meta-analysis is to provide a comprehensive summary and synthesis of clinical outcomes in the literature for CSP in comparison to BVP when facilitated with AVNA. Methods This study protocol was registered in the PROSPERO registry and the review was conducted as per the PRISMA guidelines. MEDLINE, EMBASE and Cochrane Library were searched for relevant studies from inception till January 11th, 2024. Results were synthesised using a random effects meta-analysis. Risk of bias (ROB) assessment was carried out with the RoB 2 and ROBINS-I tool. Results From a total of 259 references identified, 122 full texts were assessed and 5 studies (1 randomised control trial, 2 prospective observational studies, and 2 retrospective observational studies) were included in the review. A total of 738 patients (HBP-294 and LBBAP-444) received CSP and BVP implantation with AVNA, respectively. All devices were implanted successfully with a cumulative total of 4 patients in the HBP population demonstrating acute threshold hold increase following AVN. There was no loss of capture on follow-up in either treatment groups. HBP resulted in a narrower QRSd with a reduction of -35.3 ms (95% confidence interval [CI] -63.8 to -6.78; P&amp;lt;0.05; I2=96.6%) vs BVP. For left ventricular ejection fraction (LVEF), a weighted mean increase of 3.50% (95% CI -0.55%-7.54%; P=0.02, I2=65.8%) was observed following HBP implantation in comparison to BVP (Figure 1). Furthermore, LBBAP also demonstrated a weighted mean increase in LVEF of 6.02% (95%CI -4.05%-16.1%; P&amp;lt;0.05; I2=90.7%) in comparison to BVP. The mean NYHA score was reduced by -0.54 (95% CI -1.07 to -0.02; P=0.05, I2=65.5%) after HBP implantation when compared to BVP. There was a cumulative total of 45 and 65 events of heart failure associated hospitalisation in the HBP and BVP, respectively (OR 0.69; 95% CI 0.19-1.18; P=0.99, I2 =0.00). Conclusion To our knowledge, this is the first methodologically robust systematic review and meta-analysis evaluating the outcomes of CSP with AVNA. Overall, both CSP modalities demonstrated feasibility and application as an effective CRT alternative to facilitate AVNA along with a narrower QRSd ,improved LVEF and trend of better clinical outcomes. While these preliminary findings are promising, further RCTs will be necessary to establish the long-term efficacy and safety of this approach.

Traditional dual-chamber right ventricular pacing versus conduction system pacing in the US medicare population

Abstract Introduction Conduction system pacing (CSP) has emerged as an alternative therapy to traditional right ventricular (RV) pacing. However, the majority of CSP studies reflect small cohorts or single-center experience. Purpose This analysis aimed to compare CSP to dual chamber (DC) RV pacing in a large, population-based cohort utilizing data from the Micra Coverage with Evidence Development (CED) study. Methods Medicare administrative claims data were used to identify patients implanted with a DC RV pacemaker. Lead placement data from Medtronic’s device registration system was used to identify patients with treated with CSP (N=6,197) using a 3830 catheter-delivered lead or DC RV (non-3830 lead, non-CSP placement) (N=16,989) at the same centers. CSP patients were stratified into left bundle branch area pacing (LBBAP) (N=4,738) and His-bundle pacing (HBP) (N=1,459). Incident heart failure hospitalizations (iHFH), all-cause mortality, complication rates and reinterventions at 6 months were analyzed. Results CSP (LBBAP and HBP) patients with a 3830 catheter-delivered lead experienced significantly lower rates of iHFH (HR: 0.70, P=0.02) and all-cause mortality at 6 months compared with DC RV patients (HR: 0.66, P&amp;lt;.0001) (figure). There was no difference in complications (HR: 0.89, P=0.06) or need for reintervention (HR: 0.83, P=0.08) with LBBAP compared to DC RV, though HBP patients experienced significantly higher rates of complications (HR: 1.41, P=0.001) compared to LBBAP. Conclusion Patients treated with CSP with a 3830 catheter-delivered lead experienced significant all-cause mortality and HFH benefits compared to DC RV pacing. LBBAP had lower complications compared to HBP. These real-world results in a large cohort of Medicare patients align with findings in small clinical studies demonstrating the benefits of LBBAP. Future research will focus on understanding patient selection for CSP.Figure

His bundle pacing is continually relevant for patients with atrial fibrillation and bradycardia without prior atrioventricular nodal ablation, data from mid-term follow-up.

In patients with atrial fibrillation (AF) and symptomatic bradycardia, His Bundle pacing (HBP) is used to achieve an appropriate heart rate and physiological depolarization of the left ventricle (LV). We aimed to evaluate the impact of HBP on LV function in two different populations: normal LV ejection fraction (LVEF) and low LVEF (<50%). Patients who received HBP as de novo therapy or as an upgrade were divided into two groups based on initial LVEF, followed by echocardiographic and device monitoring. One hundred and twenty three patients (aged 76.0 [69.2-79.8] years, 74.0% men) with AF and bradycardia received HBP and completed follow-up with a median of 6.2 months (6.0-8.0). LV function remained unchanged in initially normal LV function patients (65 participants, LVEF 59.0% [55.0 - 62.0] vs. 58.0% [55.0-63.0]). In patients with low LVEF (58 participants), there was an increase in LVEF (37.5% [30.0-43.0] vs. 44.0% [35.0-50.0]; p < 0.0001), reduction of indexed LV end-systolic volume (62.4 [20.7] ml vs. 51.5 [21.5] ml; p = 0.001) and indexed LV end-diastolic volume (97.5 [26.2] ml vs. 88.1 [25.1] ml; p = 0.009), and improvement in the New York Heart Association class (2.3 [0.71] to 1.6 [0.9]; p < 0.0001). With permanent HBP, patients with AF and bradycardia and without prior atrioventricular nodal ablation did not experience LV systolic function deterioration. Those with reduced baseline LVEF experienced improvements in LV function and its reverse remodeling at the mid-term follow-up.

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

His bundle pacing (HBP) and left bundle branch pacing (LBBP) are emerging therapies for patients with heart failure and conduction disorders, offering potential advantages over traditional pacing methods. These approaches aim to restore physiological conduction and improve cardiac function more effectively. This study aims to evaluate the efficacy and safety of HBP and LBBP in patients with heart failure and conduction disturbances, comparing these techniques to conventional pacing. A comprehensive review of recent studies and clinical trials was conducted, focusing on the performance of HBP and LBBP in improving cardiac function, reducing QRS duration, and enhancing overall patient outcomes. The analysis includes data on clinical efficacy, procedural safety, and long-term benefits associated with these pacing modalities. Both HBP and LBBP have demonstrated significant improvements in cardiac function and clinical outcomes compared to conventional pacing. HBP effectively restores physiological conduction with improved synchronization and a reduction in QRS duration. LBBP has shown enhanced left ventricular activation, leading to better overall cardiac performance. Both techniques have been associated with a lower incidence of complications and a higher success rate in achieving optimal pacing thresholds. HBP and LBBP offer promising alternatives to traditional pacing for patients with heart failure and conduction disorders. These advanced pacing strategies provide superior clinical outcomes and improved cardiac function with reduced risk of complications. Further research and clinical trials are needed to fully establish the long-term benefits and safety profiles of these techniques in diverse patient populations.

Left ventricular volumes and function in successful and failed His-BundLe Pacing. A comparative prospective study.

Initial data suggest that His Bundle Pacing (HBP) could preserve long-term cardiac structure and function better than Right Ventricular Pacing (RVP), but evidence is limited. We studied consecutive patients with baseline ejection fraction (EF) ≥ 50% who underwent HBP attempt, either successful (HBP group) or failed (RVP group). Two-dimensional (2D) and three-dimensional (3D) echocardiography were carried out at baseline and after 6 months of ventricular pacing burden > 20%. Among 68 patients, 40 underwent successful HBP, and 28 RVP. The HBP and RVP groups did not differ for age, sex and pacing indication. At baseline, the HBP and RVP groups did not differ for 2D EF (62% vs. 62%), 3D EF (60% vs. 63%), 2D (-19% vs. -19%) and 3D global longitudinal strain (GLS) (-15% vs. -16%). After 6 months, 2D EF (-3.86%) and 3D EF (-5.71%) significantly decreased in the RVP group and did not change in the HBP group (p for interaction .006 and <.001, respectively). 2D GLS (3.08%) and 3D GLS (2.22%) significantly increased in the RVP group, but did not change in the HBP group (p for interaction .013 and <.016, respectively). Pacing induced cardiomyopathy (PICM) (EF drop ≥ 10% and EF < 50%) occurred in 14% (RVP) versus 0% (HBP) of patients (p = .025). Successful HBP was superior to RVP in preserving LV systolic function despite a high ventricular pacing burden, and was less frequently associated with PICM.

Review of Atrioventricular Node Ablation Combined with Permanent His-Purkinje Conduction System Pacing in Patients with Atrial Fibrillation with Heart Failure.

With the advancement of pacing technologies, His-Purkinje conduction system pacing (HPCSP) has been increasingly recognized as superior to conventional right ventricular pacing (RVP) and biventricular pacing (BVP). This method is characterized by a series of strategies that either strengthen the native cardiac conduction system or fully preserve physical atrioventricular activation, ensuring optimal clinical outcomes. Treatment with HPCSP is divided into two pacing categories, His bundle pacing (HBP) and left bundle branch pacing (LBBP), and when combined with atrioventricular node ablation (AVNA), can significantly improve left ventricular (LV) function. It effectively prevents tachycardia and regulates ventricular rates, demonstrating its efficacy and safety across different QRS wave complex durations. Therefore, HPCSP combined with AVNA can alleviate symptoms and improve the quality of life in patients with persistent atrial fibrillation (AF) who are unresponsive to multiple radiofrequency ablation, particularly those with concomitant heart failure (HF) who are at risk of further deterioration. As a result, this "pace and ablate" strategy could become a first-line treatment for refractory AF. As a pacing modality, HBP faces challenges in achieving precise localization and tends to increase the pacing threshold. Thus, LBBP has emerged as a novel approach within HPCSP, offering lower thresholds, higher sensing amplitudes, and improved success rates, potentially making it a preferable alternative to HBP. Future large-scale, prospective, and randomized controlled studies are needed to evaluate patient selection and implantation technology, aiming to clarify the differential clinical outcomes between pacing modalities.

Extraction of lumenless pacing leads from the His bundle and left bundle branch area: outcomes of the high-volume centre.

The application of conduction system pacing (CSP) in clinical practice is growing, and the need for lead extraction will also increase. The data on outcomes and safety of CSP lead extraction are limited. The aim of this study was to assess procedural outcomes and safety of CSP lead removal. Forty-seven patients from the EXTRACT Registry with the indication for CSP lead removal were enrolled in the study conducted at the Department of Electrocardiology in Katowice, Poland. Extraction technique, outcomes, safety, and complication were evaluated. Forty-three (91.5%) leads were successfully removed, and 41 (87.2%) were removed with traction only. The dwelling time of 28 extracted leads was longer than 1 year, and the oldest extracted lead was implanted for 89 months. Seven (14.9%) leads were removed from the left bundle branch (LBB) area and 36 from the His bundle (HB). Transient complete atrioventricular block occurred during the procedure in two patients. In 27 out of 31 attempts (87.1%), new CSP leads were implanted: nine (33.3%) HB pacing leads and 18 (66.7%) LBB area pacing leads. The CSP lead extraction is safe and feasible with a low complication rate and high rate of CSP lead reimplantation.

Is Conduction System Pacing Going to Be the New Gold Standard for Cardiac Resynchronization Therapy?

The current gold standard in device therapy for advanced heart failure (HF), which has been firmly established in HF management for more than 25 years, is classical biventricular pacing (BiV-CRT). In the last decade, a new pacing modality called conduction system pacing (CSP) has emerged as a variant for advanced cardiac device therapy. It provides pacing with preserved intrinsic cardiac activation by direct stimulation of the specific cardiac conduction system. The term CSP integrates the modalities of HIS bundle pacing (HBP) and left bundle branch area pacing (LBBAP), both of which have provided convincing data in smaller randomized and big non-randomized studies for the prevention of pacemaker-induced cardiomyopathy and for providing effective cardiac resynchronization therapy in patients with classical CRT-indication (primary approach or after failed CRT). Recent American guidelines proposed the term "cardiac physiological pacing" (CPP), which summarizes CSP including left ventricular septal pacing (LVSP), a technical variant of LBBAP together with classical BiV-CRT. The terms HOT-CRT (HIS-optimized CRT) and LOT-CRT (LBBP-optimized CRT) describe hybrid technologies that combine CSP with an additional coronary-sinus electrode, which is sometimes useful in patients with advanced HF and diffuse interventricular conduction delay. If CSP continues providing promising data that can be confirmed in big, randomized trials, it is likely to become the new gold standard for patients with an expected high percentage of pacing (>20%), possibly also for cardiac resynchronization therapy. CSP is a sophisticated new treatment option that has the potential to raise the term "cardiac resynchronization therapy" to a new level. The aim of this review is to provide basic technical, anatomical, and functional knowledge of these new pacemaker techniques in order to facilitate the understanding of the different modalities, as well as to provide an up-to-date overview of the existing randomized and non-randomized evidence, particularly in direct comparison to right ventricular and classical biventricular pacing.

Conduction system pacing upgrade versus biventricular pacing on pacemaker-induced cardiomyopathy: a retrospective observational study.

Objective: The feasibility of the conduction system pacing (CSP) upgrade as an alternative modality to the traditional biventricular pacing (BiVP) upgrade in patients with pacemaker-induced cardiomyopathy (PICM) remains uncertain. This study sought to compare two modalities of CSP (His bundle pacing (HBP) and left bundle branch pacing (LBBP)) with BiVP and no upgrades in patients with pacing-induced cardiomyopathy. Methods: This retrospective analysis comprised consecutive patients who underwent either BiVP or CSP upgrade for PICM at the cardiac department from 2017 to 2021. Patients with a follow-up period exceeding 12months were considered for the final analysis. Results: The final group of patients who underwent upgrades included 48 individuals: 11 with BiVP upgrades, 24 with HBP upgrades, and 13 with LBBP upgrades. Compared to the baseline data, there were significant improvements in cardiac performance at the last follow-up. After the upgrade, the QRS duration (127.81 ± 31.89 vs 177.08 ± 34.35ms, p < 0.001), NYHA class (2.28 ± 0.70 vs 3.04 ± 0.54, p < 0.05), left ventricular end-diastolic diameter (LVEDD) (54.08 ± 4.80 vs 57.50 ± 4.85mm, p < 0.05), and left ventricular ejection fraction (LVEF) (44.46% ± 6.39% vs 33.15% ± 5.25%, p < 0.001) were improved. There was a noticeable improvement in LVEF in the CSP group (32.15% ± 3.22% vs 44.95% ± 3.99% (p < 0.001)) and the BiVP group (33.90% ± 3.09% vs 40.83% ± 2.99% (p < 0.001)). The changes in QRS duration were more evident in CSP than in BiVP (56.65 ± 11.71 vs 34.67 ± 13.32, p < 0.001). Similarly, the changes in LVEF (12.8 ± 3.66 vs 6.93 ± 3.04, p < 0.001) and LVEDD (5.80 ± 1.71 vs 3.16 ± 1.35, p < 0.001) were greater in CSP than in BiVP. The changes in LVEDD (p = 0.549) and LVEF (p = 0.570) were similar in the LBBP and HBP groups. The threshold in LBBP was also lower than that in HBP (1.01 ± 0.43 vs 1.33 ± 0.32V, p = 0.019). Conclusion: The improvement of clinical outcomes in CSP was more significant than in BiVP. CSP may be an alternative therapy to CRT for patients with PICM. LBBP would be a better choice than HBP due to its lower thresholds.

Conduction System Pacing: Hope, Challenges, and the Journey Forward.

Cardiac pacing has evolved in recent years currently culminating in the specific stimulation of the cardiac conduction system (conduction system pacing, CSP). This review aims to provide a comprehensive overview of the available literature on CSP, focusing on a critical classification of studies comparing CSP with standard treatment in the two fields of pacing for bradycardia and cardiac resynchronization therapy in patients with heart failure. The article will also elaborate specific benefits and limitations associated with CSP modalities of His bundle pacing (HBP) and left bundle branch area pacing (LBBAP). Based on a growing number of observational studies for different indications of pacing therapy, both CSP modalities investigated are advantageous over standard treatment in terms of narrowing the paced QRS complex and preserving or improving left ventricular systolic function. Less consistent evidence exists with regard to the improvement of heart failure-related rehospitalization rates or mortality, and effect sizes vary between HBP and LBBAP. LBBAP is superior over HBP in terms of lead measurements and procedural duration. With regard to all reported outcomes, evidence from large scale randomized controlled clinical trials (RCT) is still scarce. CSP has the potential to sustainably improve patient care in cardiac pacing therapy if patients are appropriately selected and limitations are considered. With this review, we offer not only a summary of existing data, but also an outlook on probable future developments in the field, as well as a detailed summary of upcoming RCTs that provide insights into how the journey of CSP continues.

Safety and performance of conduction system pacing: Real-world experience from a product surveillance registry

BackgroundConduction system pacing (CSP), including His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP), has been used as an alternative for pacemaker indicated patients requiring ventricular pacing. ObjectiveThe purpose of this study was to characterize the safety and performance of HBP and LBBAP among patients enrolled in the Medtronic product surveillance registry (PSR). MethodsThis observational analysis included patients who underwent pacemaker implantations for HBP or LBBAP with a Medtronic Model 3830 lead between January 2019 and December 2023 in the Medtronic PSR. The primary outcomes were lead-related complications and pacing capture threshold. Baseline characteristics, R-wave amplitude, impedance, and all-cause mortality were summarized. ResultsA total of 2342 patients were included across 77 centers (mean age 74 years; 38.9% female). Of the patients implanted with a 3830 lead for CSP, 64.1% (n = 1502) had LBBAP placement and 35.9% (n = 840) had HBP placement. The most commonly reported indications for CSP were sinus node dysfunction (67.0%) and atrioventricular block (57.2%). LBBAP had lower pacing thresholds, higher R-wave sensing, and higher impedance (all P <.001) through 30 months. At 36 months postimplant, the lead complication rate for LBBAP and HBP was 2.5% and 6.3%, ,respectively with no difference in all-cause mortality. ConclusionIn a multicenter cohort of LBBAP and HBP patients treated with the catheter-delivered 3830 lead, lead-related complication rates were low and electrical parameters were stable through 30 months.

His bundle pacing versus left bundle branch area pacing in patients undergoing atrioventricular node ablation: A prospective and comparative study

BackgroundPacemaker implantation combined with atrioventricular node ablation (AVNA) is a well-established strategy for uncontrolled atrial arrhythmias. Limited data are available regarding His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) in this setting. AimTo compare the outcomes of HBP and LBBAP in patients undergoing pacemaker implantation combined with AVN in routine clinical practice. MethodsWe prospectively included all patients who underwent AVNA after successful conduction system pacing (CSP) in two hospitals between September 2017 and May 2023. The primary outcome was the 1-year composite of first episode of heart failure hospitalization, symptomatic atrioventricular node reconduction requiring a second AVNA procedure, lead revision or death from any cause. ResultsA total of 164 patients underwent AVNA following successful CSP (68 HBP and 96 LBBAP). Mean pacemaker implantation and AVNA procedure times were shorter in the LBBAP group than the HBP group (46±18 vs 59±23min; P<0.001 and 31±12 vs 43±22min, respectively; P<0.001). Complete atrioventricular block was more frequently obtained in the LBBAP group (88/96 patients [92%] vs 54/68 patients [79%]; P=0.04). One-year freedom from the composite outcome was more frequent in the LBBAP group (89.7% vs 72.9%; hazard ratio 0.32, 95% confidence interval 0.14−0.72; P=0.01). The strategy was similarly effective in both groups with a significant improvement in NYHA class and left ventricular ejection fraction. A secondary pacing threshold elevation >1V occurred only in the HBP group (11%). ConclusionIn this prospective, comparative study, LBBAP provided better 1-year outcomes than HBP.

Mid-term performance of His bundle pacing and usefulness of backup leads.

Ventricular backup leads may be considered in selected patients with His bundle pacing (HBP), but it remains unknown to what extent this is useful. A total of 184 HBP patients were studied. At last follow-up, 147 (79.9%) patients retained His bundle capture at programmed output. His bundle pacing lead revision was performed in 5/36 (13.9%) patients without a backup lead and in 3/148 (2.0%) patients with a backup lead (P = 0.008). One patient without a backup lead had syncope due to atrial oversensing. Thus, implantation of ventricular backup leads may avoid lead revision and adverse events in selected HBP patients.

Temporal evolution of His bundle pacing thresholds: a sub-study of the PACE-CONDUCT trial

Abstract Background His bundle pacing (HBP) has become a valuable alternative for cardiac resynchronization therapy, offering physiological pacing. This substudy of the PACE-CONDUCT trial aimed to explore the influence selective and non-selective HBP on threshold height. We assessed these parameters in patients with both normal conduction and bundle branch block conduction. Methods Our study included 61 consecutive patients with a median age of 73 years, who underwent a successful HBP implantation for indications such as sick sinus syndrome, AV Block 2 type 2, binodal disease, and ablate and pace therapy prior to AV-node ablation. Among these patients, 18 exhibited QRS durations exceeding 150 ms, indicating a complete and broad bundle branch block which made them candidates for cardiac resynchronization therapy (CRT). All patients received HBP implantation with the assistance of a 3D electroanatomical system. This system allowed for low-fluoroscopic, atraumatic evaluation of the His bundle (HB) area, presenting the His voltage as a color-coded map for precise electrode placement. Results The feasibility of bundle branch correction is generally accepted in selective HBP distal to the site of block, albeit associated with higher threshold values and potentially lower battery duration. Our analysis encompassed 61 patients who underwent HBP implantation, with 23 patients (37,7%) exhibiting selective HBP and 38 (62,3%) non-selective HBP. Remarkably, 10 out of the 23 patients with selective HBP demonstrated a complete bundle branch block correction after HBP implantation even with a basal QRS durations exceeding 150 ms. We evaluated HBP thresholds at implantation, one day post-implantation, and one month post-implantation, correlating these data with selective and non-selective HBP. Threshold values were converted to volts per millisecond (volts × milliseconds) for analysis. Statistical analysis conducted with IBM SPSS 29.0 revealed a significant difference at the day of implantation, indicating higher threshold capture in selective HBP compared to non-selective HBP (one-sided p-value: &amp;lt; 0.01, two sided p value 0.01). However, this difference could not be sustained at the one-day and one-month threshold follow-ups, suggesting normalization of the selective HBP threshold. Conclusion In our study, the initially higher threshold in selective HBP normalized within 24 hours compared to non-selective HBP. Additionally, our study demonstrated the feasibility of selective His pacing in patients with complete bundle branch block and broad QRS durations. These findings provide insights into HBP optimization and encourage further investigations with larger patient cohorts to validate our observations and enhance patient care in the realm of cardiac pacing.Threshold trend

Development of chronic thresholds in His bundle pacing: single-center experience over 7 years in 426 patients

Abstract Background Conduction system pacing (CSP), e. g. by His bundle pacing (HBP) has the potential to perform highly synchronized ventricular pacing in patients with AV block and narrow QRS complex or right bundle branch block. Therefore, CSP is recommended in these patients to prevent pacing-induced cardioomyopathy. However, there have been reports about an acute and chronic threshold increase in HBP that may cause asystole in pacemaker-dependent patients. Purpose We checked the development of chronic pacing thresholds, the incidence of dislodgements and of consecutive asystole in patients with HBP. Methods All consecutive patients with HBP attempted in our center between 6/2016 and 11/2023 were enrolled. Pacing and sensing parameters over 36 months together with the follwing events were collected and analyzed: His bundle lead dislodgement, loss of capture, threshold increase to ≥3.0V/1.0 ms, emergency admission due to syncope with loss of HBP and asystole. Results In 426 patients (78±11 years, 38% female, 90% AV block, left ventricular ejection fraction 54±10%), HBP was attempted and in 388 patients successful (47% non-selective, 53% selective HBP), 16 patients were converted to left bundle branch area pacing, 22 implantations attemps were unsuccessful. Pacing and sensing performance during follow-up are listed in the Fig. There were 3 lead dislodgements (2 patients with Twiddler syndrome), 1 loss of capture (patient with sinus node disease), and 13 increases of pacing thresholds to ≥3.0V/1.0 ms, summing up to 17 events over 3 years (4.3%). No patient had a clinical event due to threshold increase or loss of HBP capture. All His bundle threshold increases were clinically silent because patients were not pacemaker-dependent, had non-selective HBP with myocardial capture serving as a "back-up" or due to a previously implanted right ventricular back-up lead. Conclusions There is a modest pacing threshold increase in His bundle thresholds from 1.1 to 1.8V@1.0 ms over a period of 3 years. However, this did not cause clinically relevant events in our patient cohort.Chronic pacing and sensing parameters

Single-center experience with His bundle lead implantation: success rate, implantation method optimization, and lessons learned in 426 patients

Abstract Background Conduction system pacing (CSP) is increasingly used to avoid the development of pacing-induced cardiomyopathy in patients who require a high amount of ventricular pacing. His bundle pacing (HBP) is considered as ideal to achieve the narrowest paced QRS and optimal synchronization in patients with intrinsic narrow QRS or right bundle branch block but also as difficult at implantation. Purpose We analyzed our experience with HBP in terms of time and effort, pacing and sensing results, success rate, and lessons learned for optimization over a time period of 7 years. Methods All consecutive patients in whom HBP was attempted between 6/2016 and 11/2023 were included in this analysis. Implantations were performed using a pacing system analyzer (PSA) with high-resolution electrograms (EGMs). Data on implantation success [selective or non-selective HBP, left bundle branch area pacing (LBBAP)], sensing and pacing parameters, achievement of His bundle current of injury (coi), duration of implantation and fluoroscopy were collected prospectively. These results were compared for the 1st, 2nd, 3rd and 4th quartile of implantations and reasons for improvement or deterioration were analyzed. Results HBP was attempted in 426 patients (78±11 years, 38% female, 90% AV block, left ventricular ejection fraction 54±10 %, 81 single-, 286 dual-, 46 triple-chamber pacemakers, 2 dual- and 11 triple-chamber ICDs) and was successful in 404 patients (95%): 182 non-selective HBP, 206 selective HBP, and 16 LBBAP. R wave amplitude was 4.5±3.5 mV, pacing threshold 1.1 ± 0.6V/1.0 ms. In 16% of patients, a ventricular back-up lead was implanted. A His bundle coi was achieved in 61% of patients. The implantation duration was 92±43 min, fluoroscopy duration 10±8 min. Success rate increased from 89% in the 1st to 99% in the 4th quartile. Improved implantation success was associated with using a stiff 3D steerable sheath, implantation site at the distal His bundle, and an increased number of screw-in turns until a His bundle coi was visible. Conclusions Establishing an implantation routine with 1) a PSA and high-resolution EGMs, 2) use of a stiff 3D steerable sheath, 3) implantation at the distal His bundle with myocardial capture (non-selective HBP) as a back-up, and 4) an increased number of screw-in turns of the lead tip until a His bundle coi is achieved, HBP implantation can be facilitated and results optimized to a highly acceptable implantation effort and a success rate &amp;gt;95%.