[New frontiers in pacing: from myocardial pacing to conduction system pacing]. / Nuove frontiere dell'elettrostimolazione: dal pacing del miocardio comune al pacing del sistema di conduzione.

For many years, cardiac pacing has been based on the stimulation of right ventricular common myocardium to correct diseases of the conduction system. The birth and the development of cardiac resynchronization have led to growing interest in the correction and prevention of pacing-induced dyssynchrony. Many observational studies and some randomized clinical trials have shown that conduction system pacing (CSP) can not only prevent pacing-induced dyssynchrony but can also correct proximal conduction system blocks, with reduction of QRS duration and with equal or greater effectiveness than biventricular pacing. Based on these results, many Italian electrophysiologists have changed the stimulation target from the right ventricular common myocardium to CSP. The two techniques with greater clinical impact are the His bundle stimulation and the left bundle branch pacing. The latter, in particular, because of its easier implantation technique and better electric parameters, is spreading like wildfire and is representing a real revolution in the cardiac pacing field. However, despite the growing amount of data, until now, the European Society of Cardiology guidelines give a very limited role to CSP.

Utility of a guiding catheter for conduction system pacing: An early multicenter experience.

Background: Conduction system pacing (CSP), either as His bundle pacing (HBP) or as left bundle branch area pacing (LBBAP), may be superior to right ventricular apical or septal pacing. Objective: The study sought to present acute results for a new guiding catheter (Biotronik Selectra 3D) designed for CSP implantations of a retractable screw-in lead (Biotronik Solia S). Methods: The primary endpoint of the prospective, international nonrandomized BIO|MASTER.Selectra 3D study was freedom from catheter-related serious adverse device effects (SADEs) within 1 week of lead implantation. Results: Of 157 enrolled patients, CSP was achieved in 147 (93.6%) patients. No SADEs occurred within 7 days. LBBAP was achieved in 82 patients (45 as crossover from an HBP attempt) and HBP in 65 (44.2%) patients. In centers considering both HBP and LBBAP, the CSP implantation success approached 99%. Successful CSP implantations lasted on average ∼50 minutes (fluoroscopy ∼6 minutes). Most procedures (87.9%) needed only 1 catheter, even after switch from HBP to LBBAP. The catheter's handling was rated largely positive. In patients without bundle branch block, mean QRS duration increased from 106 ms (intrinsic) to 122 ms (CSP) (P = .001). In patients with bundle branch block, mean QRS duration decreased from 151 ms (intrinsic) to 137 ms (CSP) (P = .004). Conclusion: The Selectra 3D catheter is a valuable tool for HBP and LBBAP implantations of the stylet-supported pacemaker leads. When implanters considered both HBP and LBBAP, the success rate was ∼99%. Flexibility to change between different approaches may be advisable in heterogeneous and challenging areas, such as CSP implantations.

Arrhythmic Risk in Biventricular Pacing Compared With Left Bundle Branch Area Pacing: Results From the I-CLAS Study.

BACKGROUND: Left bundle branch area pacing (LBBAP) may be associated with greater improvement in left ventricular ejection fraction and reduction in death or heart failure hospitalization compared with biventricular pacing (BVP) in patients requiring cardiac resynchronization therapy. We sought to compare the occurrence of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and new-onset atrial fibrillation (AF) in patients undergoing BVP and LBBAP. METHODS: The I-CLAS study (International Collaborative LBBAP Study) included patients with left ventricular ejection fraction ≤35% who underwent BVP or LBBAP for cardiac resynchronization therapy between January 2018 and June 2022 at 15 centers. We performed propensity score-matched analysis of LBBAP and BVP in a 1:1 ratio. We assessed the incidence of VT/VF and new-onset AF among patients with no history of AF. Time to sustained VT/VF and time to new-onset AF was analyzed using the Cox proportional hazards survival model. RESULTS: Among 1778 patients undergoing cardiac resynchronization therapy (BVP, 981; LBBAP, 797), there were 1414 propensity score-matched patients (propensity score-matched BVP, 707; propensity score-matched LBBAP, 707). The occurrence of VT/VF was significantly lower with LBBAP compared with BVP (4.2% versus 9.3%; hazard ratio, 0.46 [95% CI, 0.29-0.74]; P<0.001). The incidence of VT storm (>3 episodes in 24 hours) was also significantly lower with LBBAP compared with BVP (0.8% versus 2.5%; P=0.013). Among 299 patients with cardiac resynchronization therapy pacemakers (BVP, 111; LBBAP, 188), VT/VF occurred in 8 patients in the BVP group versus none in the LBBAP group (7.2% versus 0%; P<0.001). In 1194 patients with no history of VT/VF or antiarrhythmic therapy (BVP, 591; LBBAP, 603), the occurrence of VT/VF was significantly lower with LBBAP than with BVP (3.2% versus 7.3%; hazard ratio, 0.46 [95% CI, 0.26-0.81]; P=0.007). Among patients with no history of AF (n=890), the occurrence of new-onset AF >30 s was significantly lower with LBBAP than with BVP (2.8% versus 6.6%; hazard ratio, 0.34 [95% CI, 0.16-0.73]; P=0.008). The incidence of AF lasting >24 hours was also significantly lower with LBBAP than with BVP (0.7% versus 2.9%; P=0.015). CONCLUSIONS: LBBAP was associated with a lower incidence of sustained VT/VF and new-onset AF compared with BVP. This difference remained significant after adjustment for differences in baseline characteristics between patients with BVP and LBBAP. Physiological resynchronization by LBBAP may be associated with lower risk of arrhythmias compared with BVP.

Transvenous lead extraction of lumenless 3830 pacing lead in conduction system pacing: a single-center experience.

BACKGROUND: The Medtronic SelectSecure Model 3830 lumenless lead (Medtronic, Inc., Minneapolis, MN) is commonly used for conduction system pacing (CSP). However, with this increased use, the potential need for transvenous lead extraction (TLE) also will increase. While extraction of endocardial 3830 leads is rather well described especially in pediatric and adult congenital heart disease population, there is very limited data on extraction of CSP leads. In the present study, we reported our preliminary experience on TLE of CSP leads and provided technical considerations. METHODS: The study population comprised 6 consecutive patients (67% male; mean age 70 ± 22 years) with CSP leads (3830 leads), including left bundle branch pacing (LBBP) lead (n = 3) and His pacing lead (n = 3) undergoing TLE. Overall target leads were 17. The mean implant duration time of CSP leads was 97 ± 90 months [range 8-193). RESULTS: Manual traction was successful in 2 cases and mechanical extraction tools were required in the remaining cases. Sixteen leads (94%) were completely extracted, whereas incomplete removal was observed in one lead (6%) among 1 patient. Of note, in the only lead incompletely removed, we observed retention of < 1-cm remnant of lead material consisting of the screw of 3830 LBBP lead into the interventricular septum. No failure of lead extraction was reported and no major complications occurred. CONCLUSIONS: Our findings demonstrated that at an experienced center the success of TLE of chronically implanted CSP leads is high in the absence of major complications also when mechanical extraction tools are needed.

Sex-Specific Outcomes of LBBAP Versus Biventricular Pacing: Results From I-CLAS.

BACKGROUND: Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) has been associated with greater clinical improvement in women than men. Recently, left bundle branch area pacing (LBBAP) has been shown to be an alternative form of CRT. OBJECTIVES: The purpose of this study was to investigate sex-specific outcomes for death and heart failure events in a large, international, multicenter, cohort of patients undergoing CRT with BVP or LBBAP. METHODS: In this international study of 1,778 patients (575 female and 1203 male), sex-specific survival analysis was performed to compare the effect of LBBAP-CRT relative to BVP-CRT on the combined endpoint of death or heart failure hospitalization (HFH), and secondary endpoints of HFH only, and death alone. RESULTS: Female patients were more likely to have nonischemic cardiomyopathy and left bundle branch block (LBBB) and less likely to have hypertension, diabetes, or coronary artery disease than were male patients. Overall, female patients had a better result with LBBAP compared with BVP than did male patients, with a significant 36% reduction in death or HFH (HR: 0.64; 95% CI: 0.43 to 0.97; P = 0.03) and a significant 60% reduction in HFH alone (HR: 0.4; 95% CI: 0.24 to 0.69, P < 0.01). Women had a greater reduction in death or HFH among those with nonischemic cardiomyopathy (HR: 0.45 95% CI: 0.26 to 0.79; P < 0.01) and LBBB (HR: 0.49; 95% CI: 0.27 to 0.87; P < 0.01). Sex-specific echocardiographic outcomes were better in women than in men. CONCLUSIONS: Women obtained significantly greater reductions in the combined endpoint of death or HFH (primarily driven by reduction in HFH) with LBBAP compared with BVP among patients requiring CRT than did men.

Conduction system pacing in difficult cardiac anatomies: Systematic approach with the 3D electroanatomic mapping guide.

INTRODUCTION: Restoring physiological cardiac electrical activity in patients with conduction disease can be crucial for the survival and quality of life. Conduction system pacing (CSP) is a valuable option, although it is limited by technical challenges in difficult anatomies. 3D electroanatomical mapping (3D-EAM) can support CSP ensuring high electro-anatomical precision and low fluoroscopy. OBJECTIVES: We evaluated the feasibility and effectiveness of a systematic 3D-EAM use to guide CSP in difficult anatomical scenarios (highly dilated atria, congenital cardiomyopathies, failed biventricular implants (BiV) and pacing-induced cardiomyopathy (PICM)). METHODS: Forty-three consecutive patients (27 males, 75 ± 10 years old) with standard pacing indications and difficult anatomical scenarios were included. The right atrium, His cloud, and atrio-ventricular septum were reconstructed by 3D-EAM. The His bundle (HB) was the initial target, while left bundle branch area pacing (LBBAP) was aimed at in case of unsatisfactory parameters, sub-optimally paced QRS, or impossibility of reaching the HB. RESULTS: CSP was successful in 37 (86%) patients (15 HBP; 22 LBBAP). Mean mapping, fluoroscopy, and procedural times were 18 ± 7 min, 7 ± 5 min, 98 ± 47 min, respectively. The mean pacing threshold, R wave sensing, and pacing impedance of CSP lead were 1.2 ± 0.5V@0.5ms, 11.4 ± 6.2 mV, 736 ± 306 Ω, respectively. Baseline and paced QRS were 139 ± 38 ms and 114 ± 23 ms, respectively. No procedural complications were observed. CONCLUSIONS: 3D-EAM allowed the accurate definition of the His cloud and high ventricular septum and effectively guided CSP. It facilitated CSP in complex anatomies, with a procedural success rate of 86%. The results were satisfactory and reproducible, with acceptable fluoroscopy and procedural times.

Cardiac Conduction System Pacing: A Comprehensive Update.

The field of cardiac pacing has changed rapidly in the last several years. Since the initial description of His bundle pacing targeting the conduction system, recent advances in pacing the left bundle branch and its fascicles have evolved. The field and investigators' knowledge of conduction system pacing including relevant anatomy and physiology has advanced significantly. The aim of this review is to provide a comprehensive update on recent advances in conduction system pacing.

The weakest point of cardiac resynchronization therapy: new technologies facing old terminology.

Patients with symptomatic heart failure (HF) and left bundle branch block (LBBB) are currently treated with biventricular pacing (BiV) which has a Class IA recommendation. Given the possibility to re-establish the inter and intra-ventricular synchrony, BiV is commonly referred to as cardiac resynchronization therapy (CRT). This wording is widely utilized and over time the terms BiV and CRT have become interchangeable. Conduction system pacing (CSP) is emerging as a valid therapeutic opportunity to obtain CRT restoring the native conduction via the Purkinje network. Therefore the acronym CRT is no longer synonymous with BiV only but could also refer to CSP. A terminology update is needed to include the resource of CSP to ensure better communication among all the stakeholders involved in managing recipients of cardiac devices and should be a fundamental step in advancing the quality of patient care. Making use of the NBG code to describe the implantable cardiac device would ease such terminology update, since only the first three positions of the five letters NBG code are commonly utilized, while the last two are rarely used.

Result of the Physiologic Pacing Registry, an international multicenter prospective observational study of conduction system pacing.

BACKGROUND: Conduction system pacing (CSP), including both left bundle branch area pacing (LBBAP) and His-bundle pacing (HBP) has been proposed as an alternative therapy option for patients with indication for cardiac pacing to treat bradycardia or heart failure. OBJECTIVE: The purpose of this study was to evaluate implant success, safety, and electrical performances of HBP and LBBAP in the multinational Physiological Pacing Registry. METHODS: The international prospective observational registry included 44 sites from 16 countries globally between November 2018 and May 2021. RESULTS: Of 870 subjects enrolled, CSP lead implantation was attempted in 849 patients. Subjects with successful CSP lead implantation were followed for 6 months (5 ± 2 months). CSP lead implantation was successful in 768 patients (90.4%). Implant success was 95.2% (239/251) for LBBAP and 88.5% (529/598) for HBP (P = .002). Procedural duration and fluoroscopy duration were comparable between LBBAP and HBP (P = .537). Capture threshold at implant was 0.69 ± 0.39 V at 0.46 ± 0.15 ms in LBBAP and 1.44 ± 1.03 V at 0.71 ± 0.33 ms in HBP (P <.001). Capture threshold at 6 months was 0.79 ± 0.33 V at 0.44 ± 0.13 ms in LBBAP and 1.59 ± 0.97 V at 0.67 ± 0.31 ms in HBP (P <.001). Pacing threshold rise ≥1 V was observed at 6 months in 3 of 208 (1.4%) of LBBAP and 55 of 418 (13.2%) of HBP (P <.001). Serious adverse events related to implant procedure or CSP lead occurred in 5 of 251 (2.0%) with LBBAP and 25 of 598 (4.2%) with HBP (P = .115). CONCLUSION: This large prospective multicenter study demonstrates that CSP is technically feasible in most patients with relatively higher implant success and suggests that, with current technology, LBBAP may have better pacing parameters than HBP.

Pacing of the specialized His-Purkinje conduction system: 'back to the future'.

The conduction system of the human heart is composed of specialized cardiomyocytes that initiate and propagate the electric impulse with consequent rhythmic and synchronized contraction of the atria and ventricles, resulting in the normal cardiac cycle. Although the His-Purkinje system (HPS) was already described more than a century ago, there has been a recent resurgence of conduction system pacing (CSP), where pacing leads are positioned in the His bundle region and left bundle branch area to provide physiological cardiac activation as alternatives to the unnatural myocardial stimulation obtained with conventional right ventricular and biventricular pacing. In this review, we describe the fundamental anatomical and pathophysiological aspects of the specialized HPS along with the CSP technique's nuts and bolts to highlight its potential benefits in everyday clinical practice.

Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Candidates for Resynchronization Therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP. OBJECTIVES: The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT. METHODS: This observational study included patients with LVEF ≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT from January 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes. RESULTS: A total of 1,778 patients met inclusion criteria: 981 BVP, 797 LBBAP. The mean age was 69 ± 12 years, 32% were female, 48% had coronary artery disease, and mean LVEF was 27% ± 6%. Paced QRS duration in LBBAP was significantly narrower than baseline (128 ± 19 ms vs 161 ± 28 ms; P < 0.001) and significantly narrower compared to BVP (144 ± 23 ms; P < 0.001). Following CRT, LVEF improved from 27% ± 6% to 41% ± 13% (P < 0.001) with LBBAP compared with an increase from 27% ± 7% to 37% ± 12% (P < 0.001) with BVP, with significantly greater change from baseline with LBBAP (13% ± 12% vs 10% ± 12%; P < 0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared with BVP (20.8% vs 28%; HR: 1.495; 95% CI: 1.213-1.842; P < 0.001). CONCLUSIONS: LBBAP improved clinical outcomes compared with BVP in patients with CRT indications and may be a reasonable alternative to BVP.

EHRA clinical consensus statement on conduction system pacing implantation: endorsed by the Asia Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS), and Latin American Heart Rhythm Society (LAHRS).

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last five years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique.

EHRA clinical consensus statement on conduction system pacing implantation: executive summary. Endorsed by the Asia-Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS) and Latin-American Heart Rhythm Society (LAHRS).

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique. A synopsis is provided in this print edition of EP-Europace. The full document may be consulted online, and a 'Key Messages' App can be downloaded from the EHRA website.

Worldwide survey on implantation of and outcomes for conduction system pacing with His bundle and left bundle branch area pacing leads.

BACKGROUND: Adoption and outcomes for conduction system pacing (CSP), which includes His bundle pacing (HBP) or left bundle branch area pacing (LBBAP), in real-world settings are incompletely understood. We sought to describe real-world adoption of CSP lead implantation and subsequent outcomes. METHODS: We performed an online cross-sectional survey on the implantation and outcomes associated with CSP, between November 15, 2020, and February 15, 2021. We described survey responses and reported HBP and LBBAP outcomes for bradycardia pacing and cardiac resynchronization CRT indications, separately. RESULTS: The analysis cohort included 140 institutions, located on 5 continents, who contributed data to the worldwide survey on CSP. Of these, 127 institutions (90.7%) reported experience implanting CSP leads. CSP and overall device implantation volumes were reported by 84 institutions. In 2019, the median proportion of device implants with CSP, HBP, and/or LBBAP leads attempted were 4.4% (interquartile range [IQR], 1.9-12.5%; range, 0.4-100%), 3.3% (IQR, 1.3-7.1%; range, 0.2-87.0%), and 2.5% (IQR, 0.5-24.0%; range, 0.1-55.6%), respectively. For bradycardia pacing indications, HBP leads, as compared to LBBAP leads, had higher reported implant threshold (median [IQR]: 1.5 V [1.3-2.0 V] vs 0.8 V [0.6-1.0 V], p = 0.0008) and lower ventricular sensing (median [IQR]: 4.0 mV [3.0-5.0 mV] vs. 10.0 mV [7.0-12.0 mV], p < 0.0001). CONCLUSION: In conclusion, CSP lead implantation has been broadly adopted but has yet to become the default approach at most surveyed institutions. As the indications and data for CSP continue to evolve, strategies to educate and promote CSP lead implantation at institutions without CSP lead implantation experience would be necessary.

Left bundle branch area pacing outcomes: the multicentre European MELOS study.

AIMS: Permanent transseptal left bundle branch area pacing (LBBAP) is a promising new pacing method for both bradyarrhythmia and heart failure indications. However, data regarding safety, feasibility and capture type are limited to relatively small, usually single centre studies. In this large multicentre international collaboration, outcomes of LBBAP were evaluated. METHODS AND RESULTS: This is a registry-based observational study that included patients in whom LBBAP device implantation was attempted at 14 European centres, for any indication. The study comprised 2533 patients (mean age 73.9 years, female 57.6%, heart failure 27.5%). LBBAP lead implantation success rate for bradyarrhythmia and heart failure indications was 92.4% and 82.2%, respectively. The learning curve was steepest for the initial 110 cases and plateaued after 250 cases. Independent predictors of LBBAP lead implantation failure were heart failure, broad baseline QRS and left ventricular end-diastolic diameter. The predominant LBBAP capture type was left bundle fascicular capture (69.5%), followed by left ventricular septal capture (21.5%) and proximal left bundle branch capture (9%). Capture threshold (0.77 V) and sensing (10.6 mV) were stable during mean follow-up of 6.4 months. The complication rate was 11.7%. Complications specific to the ventricular transseptal route of the pacing lead occurred in 209 patients (8.3%). CONCLUSIONS: LBBAP is feasible as a primary pacing technique for both bradyarrhythmia and heart failure indications. Success rate in heart failure patients and safety need to be improved. For wider use of LBBAP, randomized trials are necessary to assess clinical outcomes.

Prognostic Impact of New-Onset Atrial Fibrillation After Single or Double Stent Left Main Bifurcation PCI.

OBJECTIVE: Incidence and prognostic value of new-onset atrial fibrillation after single versus double stent strategy in bifurcation left main disease has not been yet investigated. METHODS: We retrospectively analyzed the procedural and medical data of patients referred to our center for complex left main bifurcation disease, treated using crossover provisional stenting, T or T-and-Protrusion, Culotte, and Nano-inverted-T techniques between January 1, 2008, and May 1, 2018. Multivariate Cox-regression analysis was used to assess the role of different stent strategies, adjusted for confounders, on the risk of new-onset atrial fibrillation during the follow-up period. RESULTS: Five hundred two patients (316 males, mean age 70.3 ± 12.8 years, mean Syntax score 31.6 ± 6.3) were evaluated. At a mean follow-up of 37.1 ± 10.8 months (range: 22.1- 39.3 months); Target lesion failure rate was 10.1%. Stent thrombosis and cardiovascular mor- tality were observed in 1.2% and 3.6% in of cases, respectively. New-onset atrial fibrillation occurred in 23 out of 502 patients (4.6%). Patients with new-onset atrial fibrillation resulted more frequently female, older, obese, and diabetic and more frequently experienced target lesion failure and cardiovascular death. New-onset atrial fibrillation-free survival favored single versus double stent technique and among double stent techniques nano-inverted-T tech- niques compared to the others. Single stent strategy had a lower risk of new-onset atrial fibril- lation compared to double stent technique on multivariate analysis (Hazard Ratio (HR): 1.14, 95% CI: 1.10-1.19, P < .001 vs. HR: 1.28, 95% CI: 1.23-1.32, P < .0001). CONCLUSION: New-onset atrial fibrillation in distal left main bifurcation disease treated with per- cutaneous coronary intervention had a low incidence but resulted more frequently after double than after single stenting technique and was associated with worse outcomes.

His Bundle Pacing: My Experience, Tricks, and Tips.

His Bundle Pacing (HBP) is a form of physiologic pacing achieved through implantation of a pacing electrode into the His bundle. HBP began 20 years ago without any dedicated tools. As specific tools became available HBP quickly spread and proved to be a viable alternative to traditional right ventricle pacing. HBP is reliable and effective in preserving the physiologic ventricular synchrony with clinical benefits particularly evident when a high percentage of pacing is required. Unipolar signals from the lead tip guide the implant. 3D electroanatomical mapping could further assist the procedure.