Search

Background: Cardiac resynchronization therapy (CRT) is a guideline-recommended therapy in patients with heart failure with mildly reduced ejection fraction (HFmrEF, 36%-50%) and left bundle branch block or indication for ventricular pacing. Conduction system pacing (CSP) using left bundle branch area pacing or His bundle pacing has been shown to be a safe and physiologic alternative to biventricular pacing (BVP)., Objective: The aim of this study was to compare the clinical outcomes between BVP and CSP for patients with HFmrEF undergoing CRT., Methods: Consecutive patients who underwent BVP or CSP with HFmrEF between January 2018 and June 2023 at 16 international centers were included. The primary outcome was the composite end point of time to death or heart failure hospitalization (HFH). Secondary end points included change in left ventricular ejection fraction (LVEF) and individual end points of death and HFH., Results: A total of 1004 patients met inclusion criteria: BVP, 178; CSP, 826 (His bundle pacing, 154; left bundle branch area pacing, 672). Mean age was 73 ± 13 years; female, 34%; and LVEF, 42% ± 5%. Paced QRS duration in CSP was significantly narrower compared with BVP (129 ± 21 ms vs 144 ± 19 ms; P < .001). LVEF improved during follow-up in both groups (49% ± 10% vs 48% ± 10%; P = .32). CSP was independently associated with significant reduction in the primary end point of time to death or HFH compared with BVP (22% vs 34%; hazard ratio, 0.64; 95% confidence interval, 0.43-0.94; P = .025)., Conclusion: CSP was associated with improved clinical outcomes compared with BVP in this large cohort of patients with HFmrEF undergoing CRT. Randomized controlled trials comparing CSP with BVP will be necessary to confirm these results., Competing Interests: Disclosures P.V.: honoraria, consultant, research, fellowship support—Medtronic; consultant—Abbott, Eaglepoint LLC; honoraria—Boston Scientific, Biotronik; patent: HBP delivery tool. F.Z.: honoraria—Abbott, Biotronik, Boston Scientific, Medtronic, and MicroPort; S.S.P.: honoraria—Medtronic; B.H.: speaker, consultant—Abbott; speaker, fellowship support—Medtronic; P.S.: honoraria—Medtronic; consultant—Medtronic, Abbott, Biotronik; M.J.: honoraria, consultant—Medtronic, Abbott; K.V.: consultant—Biosense Webster, Medtronic, Abbott, Boston Scientific; institution has received research and educational grants from Abbott, Medtronic, Biosense Webster; Z.W.: honoraria—Medtronic, Boston Scientific; consultant—Medtronic, Abbott; K.C.: consultant and honoraria from Medtronic, Biotronik, and Abbott; M.G.C.: research support—PCORI, NIH, Abbott, Impulse Dynamics; honorarium—Impulse Dynamics; G.U.: consulting or speaking from Abbott, Biotronik, Boston Scientific, GE Medical, Medtronic, Philips, Rhythm Science, and Zoll Medical; R.K.P.: honoraria, consultant, research, fellowship support—Medtronic, Abbott; O.C.: honoraria, consultant—Medtronic, Biotronik, Boston Scientific, and MicroPort. All others authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Left bundle branch area pacing (LBBAP) comprises pacing at the left ventricular septum (LVSP) or left bundle branch (LBBP). The aim of the present study was to investigate the differences in ventricular electrical heterogeneity between LVSP, LBBP, right ventricular pacing (RVP) and intrinsic conduction with different dyssynchrony measures using the ECG, vectorcardiograpy, ECG belt, and Ultrahigh frequency (UHF-)ECG., Methods: Thirty-seven patients with a pacemaker indication for bradycardia or cardiac resynchronization therapy underwent LBBAP implantation. ECG, vectorcardiogram, ECG belt and UHF-ECG signals were recorded during RVP, LVSP and LBBP, and intrinsic activation. QRS duration (QRSd) was measured from the ECG, QRS area was calculated from the vectorcardiogram, LV activation time (LVAT) and standard deviation of activation time (SDAT) from ECG belt and electrical dyssynchrony (e-DYS16) from UHF-ECG., Results: Both LVSP and LBBP significantly reduced ventricular electrical heterogeneity as compared to underlying LBBB and RV pacing in terms of QRS area (p < .001), SDAT (p < .001), LVAT (p < .001) and e-DYS16 (p < .001). QRSd was only reduced as compared to RV pacing(p < .001). QRS area was similar during LBBP and normal intrinsic conduction, e-DYS16 was similar during LVSP and normal intrinsic conduction, whereas SDAT was similar for LVSP, LBBP and normal intrinsic conduction. For all these variables there was no significant difference between LVSP and LBBP., Conclusion: Both LVSP and LBBP resulted in a more synchronous LV activation than LBBB and RVP. Especially LBBP resulted in levels of LV synchrony comparable to normal intrinsic conduction., (© 2024 The Author(s). Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background: Continuous deep septal pacing and signal recording during implantation of left bundle branch pacing (LBBP) lead enables to monitor beat-to-beat changes of electrocardiogram (ECG) and myocardial current of injury (COI) as the lead crosses the septum., Objectives: This study aimed to characterize patterns of continuous QRS, ST-T, and COI change for monitoring of the lead depth and instantaneous determination of the obtained capture type (LBBP vs left ventricular septal pacing [LVSP])., Methods: The ECG and COI during lead implantation were scrutinized for sudden changes of V 6 R-wave peak time, V 1  initial and terminal R-wave amplitude, V 3 -V 6 R-wave amplitude, repolarization pattern and S-wave amplitude in I, V 5 -V 6 , and COI drop. The sudden and gradual transition patterns were diagnosed depending on the presence or absence of the above beat-to-beat ECG phenomena, respectively., Results: A total of 212 pacemaker recipients were analyzed; LBBP and LVSP were obtained in 77.4% and 22.6%, respectively. There were 4.7 ± 2.1 and 0.2 ± 0.6 beat-to-beat phenomena in LBBP and LVSP patients, respectively. The sudden transition pattern, recognized in 80.7%, had sensitivity and specificity for LBBP diagnosis of 98.8% and 81.2%, respectively. A sudden drop of COI (29.4 ± 8.5 mV to 12.8 ± 4.9 mV) was observed in 53.9% patients (LBBP was simultaneously obtained in 92.7%)., Conclusions: Capture of left bundle branch during lead penetration is a beat-to-beat phenomenon. Two transseptal transition patterns were identified: 1) sudden, which is typical for obtaining LBBP; and 2) gradual, which is typical for obtaining LVSP. A sudden COI drop, a very observable phenomenon, also identified reaching the left subendocardial area., Competing Interests: Funding Support and Author Disclosures Dr Jastrzębski has received lecture, consultation, and/or proctoring fees from Medtronic, Biotronik, and Abbott; and has served on an advisory board for Boston Scientific. Dr Kiełbasa has received lecture fees from Medtronic and Biotronik. Dr Moskal has received lecture, consultation, and/or proctoring fees from Medtronic and Biotronik. Dr Burri has received speaker honoraria, advisory board fees, and/or institutional research support from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Curila has received consulting fees and honoraria from Medtronic, Biotronik, and Abbott. Dr Vijayaraman has received honoraria, consulting fees, and research and fellowship support from Medtronic; has received consulting fees from Abbott; has received honoraria from Boston Scientific and Biotronik; and has a patent for an HBP delivery tool. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The effect of left ventricular septal myocardial pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and left ventricular (LV) hemodynamic status is poorly understood., Objectives: The aim of this study was to investigate the impact of LVSP and LBBP vs biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamic status in cardiac resynchronization therapy patients., Methods: In cardiac resynchronization therapy candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRS duration (QRSd) and using ultra-high-frequency electrocardiography. LV electrical dyssynchrony was assessed as the difference between the first activation in leads V 1 to V 8 to the last from leads V 4 to V 8 . LV hemodynamic status was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP., Results: A total of 35 patients with a mean LV ejection fraction of 29% and a mean QRSd of 168 ± 24 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LV electrical dyssynchrony than BVP (-10 ms; 95% CI: -16 to -4 ms; P = 0.001); the difference between LVSP and BVP was not significant (-5 ms; 95% CI: -12 to 1 ms; P = 0.10). LBBP was associated with higher systolic blood pressure than BVP (4%; 95% CI: 2%-5%; P < 0.001), whereas LVSP was not (1%; 95% CI: 0%-2%; P = 0.10). Hemodynamic differences during LBBP and LVSP vs BVP were more pronounced in nonischemic than ischemic patients., Conclusions: Ultra-high-frequency electrocardiography allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamic status as BVP, while LBBP was better than BVP in both., Competing Interests: Funding Support and Author Disclosures This work was supported by the Charles University Research Program Cooperation-Cardiovascular Science (Dr Curila), the Ministry of Health of the Czech Republic (grant NU21-02-00584 to Dr Curila), and National Institute for Metabolic and Cardiovascular Research “CarDia” (Programme EXCELES, ID Project No. LX22NPO5104), funded by the European Union – Next Generation EU (Dr Curila). Authors from the Cardiocenter, Third Faculty of Medicine, Charles University and University Hospital Kralovske Vinohrady, from Institute of Scientific Instruments, the Czech Academy of Sciences, have filed U.S. patent 11,517,243 B2, “Method of Electrocardiographic Signal Processing and Apparatus for Performing the Method” and are shareholders of VDI Technologies. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

From precordial ECG leads, the conventional determination of the negative derivative of the QRS complex (ND-ECG) assesses epicardial activation. Recently we showed that ultra-high-frequency electrocardiography (UHF-ECG) determines the activation of a larger volume of the ventricular wall. We aimed to combine these two methods to investigate the potential of volumetric and epicardial ventricular activation assessment and thereby determine the transmural activation sequence. We retrospectively analyzed 390 ECG records divided into three groups-healthy subjects with normal ECG, left bundle branch block (LBBB), and right bundle branch block (RBBB) patients. Then we created UHF-ECG and ND-ECG-derived depolarization maps and computed interventricular electrical dyssynchrony. Characteristic spatio-temporal differences were found between the volumetric UHF-ECG activation patterns and epicardial ND-ECG in the Normal, LBBB, and RBBB groups, despite the overall high correlations between both methods. Interventricular electrical dyssynchrony values assessed by the ND-ECG were consistently larger than values computed by the UHF-ECG method. Noninvasively obtained UHF-ECG and ND-ECG analyses describe different ventricular dyssynchrony and the general course of ventricular depolarization. Combining both methods based on standard 12-lead ECG electrode positions allows for a more detailed analysis of volumetric and epicardial ventricular electrical activation, including the assessment of the depolarization wave direction propagation in ventricles., (© 2024. The Author(s).)

Identifying electrical dyssynchrony is crucial for cardiac pacing and cardiac resynchronization therapy (CRT). The ultra-high-frequency electrocardiography (UHF-ECG) technique allows instantaneous dyssynchrony analyses with real-time visualization. This review explores the physiological background of higher frequencies in ventricular conduction and the translational evolution of UHF-ECG in cardiac pacing and CRT. Although high-frequency components were studied half a century ago, their exploration in the dyssynchrony context is rare. UHF-ECG records ECG signals from eight precordial leads over multiple beats in time. After initial conceptual studies, the implementation of an instant visualization of ventricular activation led to clinical implementation with minimal patient burden. UHF-ECG aids patient selection in biventricular CRT and evaluates ventricular activation during various forms of conduction system pacing (CSP). UHF-ECG ventricular electrical dyssynchrony has been associated with clinical outcomes in a large retrospective CRT cohort and has been used to study the electrophysiological differences between CSP methods, including His bundle pacing, left bundle branch (area) pacing, left ventricular septal pacing and conventional biventricular pacing. UHF-ECG can potentially be used to determine a tailored resynchronization approach (CRT through biventricular pacing or CSP) based on the electrical substrate (true LBBB vs. non-specified intraventricular conduction delay with more distal left ventricular conduction disease), for the optimization of CRT and holds promise beyond CRT for the risk stratification of ventricular arrhythmias.

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., Competing Interests: Disclosures Dr Herweg is a speaker and consultant for Abbott; is a speaker and receives fellowship support from Medtronic. Dr Sharma has received honoraria from Medtronic and Biotronik, and is a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from and is a consultant for Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Jastrzebski has received honoraria and is a consultant for Medtronic and Abbott. Dr Chelu has received research support from Patient-Centered Outcomes Research Institute (PCORI), National Institutes of Health (NIH), Abbott, Impulse Dynamics, and an honorarium from Impulse Dynamics. Dr Vernooy has been a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; his institution has received research and educational grants from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic and Boston Scientific and is a consultant for Medtronic and Abbott. Dr Nair has received grants in aid from Biosense Webster, Medtronic Inc., CIHR, and Heart and Stroke Foundation of Canada, and honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila is a consultant for and has received honoraria from Medtronic, Biotronik, and Abbott. Dr Subzposh has received honoraria from Medtronic. Dr Ellenbogen is a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik, and has received honoraria from Medtronic, Boston Scientific, and Biotronik. Dr Vijayaraman has received honoraria and consultant, research, and fellowship support from Medtronic; he is a consultant for Abbott, Eaglepoint LLC, and has received honoraria from Boston Scientific, Biotronik, and holds a patent for a His bundle pacing delivery tool. The remaining authors report no conflicts of interest.

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., Competing Interests: Funding Support and Author Disclosures Dr Subzposh has received honoraria from Medtronic. Dr Sharma has received honoraria from Medtronic; and has served as a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from, and has served as a consultant for, Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Herweg has served as a speaker and a consultant for Abbott; and has been a speaker for, and recipient of fellowship support from, Medtronic. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Jastrzebski has received honoraria from, and served as a consultant for, Medtronic and Abbott. Dr Chelu has received research support from PCORI, NIH, Abbott, Impulse Dynamics; and has received an honorarium from Impulse Dynamics. Dr Vernooy has served as a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; and his institution has received research and educational grants from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic, and Boston Scientific; and has served as a consultant for Medtronic and Abbott. Dr Nair has received a grant-in-aid from Biosense Webster and Medtronic Inc, CIHR, and Heart and Stroke Foundation of Canada; and has received honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila has served as a consultant for, and has received honoraria from, Medtronic, Biotronik, and Abbott. Dr Ellenbogen has served as a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik; and has received honoraria from Medtronic, Boston Scientific, and Biotronik. Dr Vijayaraman has received honoraria and research and fellowship support from, and has served as a consultant for, Medtronic; has served as a consultant for Abbott and Eaglepoint LLC; has received honoraria from Boston Scientific and Biotronik; and holds a patent for HBP delivery tool. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Karol Curila and Pavel Jurak have filed an US patent No: US 11,517,243B2: "Method of electrocardiographic signal processing and apparatus for performing the method.", and are shareholders of the company VDI technologies.

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., Competing Interests: Funding Support and Author Disclosures Work on anatomy was made possible by support from National Institutes of Health grants OT2OD023848 (to Dr K Shivkumar) and from the Tawara-McAlpine Festschrift (a component of the UCLA Amara-Yad Project). Dr Vijayaraman has received honoraria, consulting fees, and research and fellowship support from Medtronic; honoraria from Biotronik and Boston Scientific; and consulting fees from Abbott; and holds a patent for an HBP delivery tool. Dr Chelu has received research support from PCORI, National Institutes of Health, Abbott, and Impulse Dynamics; and honoraria from Impulse Dynamics. Dr Curila has received consulting fees and honoraria from Medtronic, Biotronik, and Abbott; has filed U.S. patent: US11,517,243B2: “Method of electrocardiographic signal processing and apparatus for performing the method”; and is a shareholder of VDI Technologies. Dr Dandamudi has received honoraria and consulting fees from Medtronic; and served on advisory boards of Medtronic, Biotronik, and Abbott. Dr Herweg has served as a speaker and consultant for Abbott; and has received speaking fees and fellowship support from Medtronic. Dr Jastrzebski has received honoraria and consulting fees from Medtronic and Abbott. Dr Sharma has received honoraria from Medtronic; and consulting fees from Medtronic, Abbott, Biotronik, and Boston Scientific. Dr Shivkumar is a cofounder of NeuCures Inc. Dr Tung has received honoraria and consulting fees from– Abbott. Dr Upadhyay has received honoraria from and served on advisory boards for Abbott, Biotronik, Boston Scientific, Medtronic, Philips BioTel, and Zoll Medical. Dr Vernooy has received consulting fees from Biosense Webster, Philips, Medtronic, and Abbott; honoraria from Microport; and research and educational grants (paid to institution) from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic and Boston Scientific; and consulting fees from Medtronic and Abbott. Dr Zanon has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Ellenbogen has received consulting fees from Medtronic, Boston Scientific, Abbott, and Biotronik; and honoraria from Medtronic, Boston Scientific, and Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

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., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

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., Competing Interests: Funding Support and Author Disclosures Dr Vijayaraman has received honoraria and consultancy, research, and fellowship support from Medtronic; has served as a consultant for Abbott and Eaglepoint; has received honoraria from Boston Scientific and Biotronik; and has a patent for a His bundle pacing delivery tool. Dr Sharma has received honoraria from Medtronic; and has served as a consultant for Medtronic, Abbott, and Biotronik. Dr Cano has received honoraria from and served as a consultant for Medtronic, Biotronik, and Boston Scientific. Dr Ponnusamy has received honoraria from Medtronic. Dr Herweg has served as a speaker and consultant for Abbott; and has received speaking and fellowship support from Medtronic. Dr Jastrzebski has received honoraria from and served as a consultant for Medtronic and Abbott. Dr Zou has received honoraria from Abbott, Biotronik, Boston Scientific, Medtronic, and Microport. Dr Chelu has received research support from Patient-Centered Outcomes Research Institute, National Institutes of Health, Abbott, and Impulse Dynamics; and has received honorarium from Impulse Dynamics. Dr Vernooy has served as a consultant for Biosense Webster, Philips, Medtronic, Abbott, and Boston Scientific; and has received research and educational grants to his institution from Philips, Abbott, Medtronic, and Biosense Webster. Dr Whinnett has received honoraria from Medtronic and Boston Scientific; and has served as a consultant for Medtronic and Abbott. Dr Nair has received grants-in-aid from Biosense Webster, Medtronic, Canadian Institutes of Health Research, and Heart and Stroke Foundation of Canada; and has received honoraria and consulting fees from Medtronic, Biosense Webster, and Boston Scientific. Dr Curila has served as a consultant for and received honoraria from Medtronic, Biotronik, and Abbott. Dr Ellenbogen has served as a consultant for Medtronic, Boston Scientific, Abbott, and Biotronik; and has received honoraria from Medtronic, Boston Scientific, and Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Biventricular pacing (Biv) and left bundle branch area pacing (LBBAP) are methods of cardiac resynchronization therapy (CRT). Currently, little is known about how they differ in terms of ventricular activation. This study compared ventricular activation patterns in left bundle branch block (LBBB) heart failure patients using an ultra-high-frequency electrocardiography (UHF-ECG). This was a retrospective analysis including 80 CRT patients from two centres. UHF-ECG data were obtained during LBBB, LBBAP, and Biv. Left bundle branch area pacing patients were divided into non-selective left bundle branch pacing (NSLBBP) or left ventricular septal pacing (LVSP) and into groups with V6 R-wave peak times (V6RWPT) < 90 ms and ≥ 90 ms. Calculated parameters were: e-DYS (time difference between the first and last activation in V1-V8 leads) and Vdmean (average of V1-V8 local depolarization durations). In LBBB patients ( n = 80) indicated for CRT, spontaneous rhythms were compared with Biv (39) and LBBAP rhythms (64). Although both Biv and LBBAP significantly reduced QRS duration (QRSd) compared with LBBB (from 172 to 148 and 152 ms, respectively, both P < 0.001), the difference between them was not significant ( P = 0.2). Left bundle branch area pacing led to shorter e-DYS (24 ms) than Biv (33 ms; P = 0.008) and shorter Vdmean (53 vs. 59 ms; P = 0.003). No differences in QRSd, e-DYS, or Vdmean were found between NSLBBP, LVSP, and LBBAP with paced V6RWPTs < 90 and ≥ 90 ms. Both Biv CRT and LBBAP significantly reduce ventricular dyssynchrony in CRT patients with LBBB. Left bundle branch area pacing is associated with more physiological ventricular activation., Competing Interests: Conflict of interest: Faculty Hospital Kralovske Vinohrady, Prague, Czech Republic, and Institute of Scientific Instruments CAS, Brno, Czech Republic, have filed a European patent application EP 19212534.2: Method of electrocardiographic signal processing and apparatus for performing the method. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Targets for right-sided conduction system pacing (CSP) include His bundle and right bundle branch. Electrocardiographic patterns, diagnostic criteria, and outcomes of right bundle branch pacing (RBBP) are not known., Objective: Our aims were to delineate electrocardiographic and electrophysiological characteristics of RBBP and to compare outcomes between RBBP and His bundle pacing (HBP)., Methods: Patients with confirmed right CSP were divided according to the conduction system potential to QRS complex interval at the pacing lead implantation site. Six hypothesized RBBP criteria as well as pacing parameters, echocardiographic outcomes, and all-cause mortality were analyzed., Results: All analyzed criteria discriminated between HBP and RBBP: double QRS complex transition during the threshold test, selective paced QRS complex different from conducted QRS complex, stimulus to selective-QRS complex > potential-QRS complex, small increase in V 6 R-wave peak time (V 6 RWPT) during QRS complex transition, equal capture thresholds of CSP and myocardium, and stimulus-V 6 RWPT > potential-V 6 RWPT (adopted as the diagnostic standard). According to the last criterion, RBBP was observed in 19.2% of patients (64 of 326) who had been targeted for HBP, present mainly among patients with potential to QRS complex interval <35 ms (90.6% [48 of 53]) and occasionally among the remaining patients (5.6% [16 of 273]). RBBP was characterized by longer QRS complex (by 10.5 ms), longer V 6 RWPT (by 11.6 ms), and better sensing (by 2.6 mV) compared with HBP. During a median follow-up duration of 29 months, no differences in capture threshold, echocardiographic outcomes, or mortality were found., Conclusion: RBBP has distinct features that separate it from HBP and is observed in approximately a fifth of patients in whom HBP is intended., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)