Conduction system pacing in extensive left conduction disease and prior ablation of the right bundle branch

Conduction system pacing in extensive left conduction disease and prior ablation of the right bundle branch | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 7 March 2026 V1 Latest version Share on Conduction system pacing in extensive left conduction disease and prior ablation of the right bundle branch Authors : Mohamed Zuhair 0000-0002-3678-1932 [email protected] , Akriti Naraen 0000-0002-1681-2981 , Ian Wright , Nandita Kaza , Ahran D Arnold , Zachary Whinnett , and Daniel Keene MbCHb MSc Authors Info & Affiliations https://doi.org/10.22541/au.177286518.87761198/v1 160 views 107 downloads Contents Abstract Key Clinical Message Introduction Case History/Examination Differential Diagnosis, Investigations and Treatment Conclusion and Results (Outcome and Follow-Up) Discussion Supporting Information Author Contribution Statement Figure Legends Abbreviations References Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract This case report presents the successful implantation of a left bundle area pacing lead in a 64-year-old male with a history of bundle branch ventricular tachycardia and consequent therapeutic ablation of the right bundle branch. Despite extensive conduction disease, effective physiological pacing was achieved as part of a cardiac synchronisation pacing Conduction System Pacing in Extensive Left Conduction Disease and Prior Ablation of the Right Bundle Branch Mohamed Zuhair MRCP 1 , Akriti Naraen MRCP 1 , Ian Wright PGCert 2 , Nandita Kaza MRCP 1 , Ahran Arnold PhD 1 , Zachary Whinnett PhD 1 , Daniel Keene PhD 1 1 Imperial College London, National Heart and Lung Institute 2 Imperial College London NHS Foundation Trust Corresponding author: Mohamed Zuhair, [email protected] Keywords: Conduction system pacing, physiological pacing, bundle branch re-entrant ventricular tachycardia, conduction system disease Data Availability Statement: The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Conflict of Interest: No conflicts of interest to disclose. Informed Consent: Written informed consent was obtained from the patient for the publication of this case report and any accompanying images and videos. Key Clinical Message Left bundle area pacing can achieve effective conduction system capture and physiological ventricular activation even in patients with extensive conduction system disease, including prior right bundle branch ablation. Non-invasive epicardial mapping may aid confirmation of conduction system capture when standard ECG criteria are inconclusive. Introduction In patients with pre-existing conduction disease, traditional right ventricular (RV) pacing can lead to pacing-induced cardiomyopathy due to dyssynchronous heart activation. Cardiac pacing strategies have evolved significantly over recent years to include direct stimulation of the conduction system, including left bundle area pacing (LBAP) and His-bundle pacing. Conduction system pacing (CSP) has been shown to reduce pacing-induced cardiomyopathy since these modalities promote a more physiological activation and restore a level of synchrony (1). This case highlights the utility of left bundle area pacing as a strategy to prevent pacing-induced cardiomyopathy in a patient with prior right bundle branch ablation for bundle branch ventricular tachycardia (VT) who later developed complete atrioventricular block. Independent Researcher Case History/Examination A 64-year-old man with a history of type 2 diabetes, hypertension, and previous myocardial infarction presented with sudden onset dizziness, followed by chest pain, shortness of breath and palpitations. His presenting electrocardiogram (ECG; Figure 1A) showed broad complex tachycardia, which later terminated to sinus rhythm with underlying left bundle branch block (LBBB; Figure 1B). One year after initial treatment, the patient presented to another hospital with complete heart block (CHB), leading to implantation of a dual chamber pacemaker, with the RV lead placed on the RV septum. After a further four years he was seen to have a high RV pacing burden (90%) with only a right bundle branch block (RBBB) escape rhythm present at 30–35 bpm. An up-to-date echocardiogram showed an ejection fraction of 44% with a diastolic left ventricular internal dimension of 4 cm. This was confirmed by MRI imaging which also revealed lateral wall fibrosis. Differential Diagnosis, Investigations and Treatment An angiogram performed at initial presentation revealed severe stenosis in the midsection of the left anterior descending artery, necessitating percutaneous coronary intervention. Echocardiography showed moderate left ventricular (LV) systolic impairment with regional wall motion abnormality affecting the inferior, septal and apical walls. The broad complex tachycardia was subsequently investigated with an electrophysiological study, identifying bundle branch re-entry VT, which was treated with therapeutic ablation of the right bundle branch (Figure 1C). Given the patient’s known conduction disease, high RV pacing burden, and mildly impaired LV function, he was enrolled in a CSP pacemaker upgrade trial for patients with mild to moderate LV impairment and over 40% RV pacing burden (PROTECT-UP; ClinicalTrials.gov: NCT06052475). Given the patient’s known conduction disease and previously ablated right bundle, the feasibility and deliverability of upgrading to a left bundle area pacing system was questioned. However, the patient was successfully upgraded to cardiac resynchronisation therapy with the implantation of a left bundle lead. Due to the presence of lateral scar, a conventional LV lead was not considered in the first instance. The ECGs in Figure 2 show the difference in the activation patterns of RV pacing from the RV septal lead and the left bundle branch pacing lead. This patient also underwent non-invasive epicardial mapping with a CardioInsight 252-electrode ECG imaging (ECGi) vest (Medtronic, Minneapolis, USA) to demonstrate the activation patterns with intrinsic rhythm, RV pacing and left bundle branch pacing (Figure 3; Video S1). Conclusion and Results (Outcome and Follow-Up) Despite the extensive conduction system disease, effective physiological pacing was achieved. While some features of the European Heart Rhythm Association CSP ECG criteria (4) were not demonstrated (no R’ and no threshold transition), a relatively short R wave peak time of 82 ms in V6 was observed as well as a large reduction in QRS duration from 166 to 112 ms, making myocardial-only capture unlikely. ECGi mapping demonstrated distinct epicardial activation patterns across the three modalities. In intrinsic RBBB rhythm, the LV activated early and the RV was late. In RV pacing, the RV activated early prior to the anterior LV wall, followed by the lateral wall. In left bundle branch pacing, there was early basal RV activation, likely due to the local myocardial capture of non-selective left bundle branch pacing, prior to basal anterior activation, followed by late RV activation. However, the local activation time range showed that this late LV activation was more than 40 ms earlier than the lateral LV activation seen during RV pacing. The epicardial propagation cines (Video S1) show smooth rapid apex-to-base activation of the LV, strongly suggesting conduction system capture. Left bundle area pacing demonstrated early activation of the right basal wall, with two wavefronts moving anteriorly and posteriorly and colliding at the left apical walls. More of the anterior LV was recruited earlier with left bundle area pacing than intrinsic and RV pacing. The LV activation time was 63 ms with left bundle area pacing compared to 78 ms with intrinsic rhythm and 119 ms with RV pacing. The overall activation time was 118 ms for intrinsic, 126 ms for RV pacing and 129 ms for left bundle area pacing. Successful CSP, with a more efficient activation pattern, was thus achieved in this patient with diffuse conduction system disease. Discussion Left bundle area pacing is a rapidly growing pacing modality that has shown benefit in large observational studies compared to conventional ventricular and biventricular pacing as an anti-bradycardia and cardiac resynchronisation therapy, respectively (2, 3). In this case, left bundle area pacing was used to overcome extensive conduction disease in a patient with impaired LV function and a high RV pacing burden. This patient had known LBBB and an ablated right bundle branch, indicating severe conduction system disease. MRI imaging had revealed the presence of significant lateral wall fibrosis which may well have posed a challenge for conventional coronary sinus lead placement. Hence, documenting the success of CSP approaches in such cases is of value to the pacing community. We believe conduction system capture was achieved, but the standard ECG criteria were not observed likely given the extensive conduction system disease. While ECG-based predictors of successful conduction system recruitment have been described (5), these criteria may be less reliable in patients with extensive pre-existing conduction disease. This underscores the need for clinical nuance when interpreting CSP ECG criteria, as not all patients with successful conduction system capture will demonstrate the typical electrocardiographic features. ECGi was used in this case as a helpful non-invasive tool for understanding the epicardial activation patterns. Utilising low-dose CT-derived cardiac and torso geometry and mathematical combination with data from a 252-lead surface ECG, epicardial activation times were produced. These observations suggest that the last area of the ventricle is still activated more efficiently during left bundle area pacing than during intrinsic rhythm and RV pacing. This finding further supports the recruitment of the conduction system during left bundle area pacing. This case demonstrates that left bundle branch area pacing is feasible even in patients with extensive conduction system disease, and highlights the importance of appreciating the degree of intrinsic conduction system disease and the complexities it can pose on confirming capture with left bundle area pacing. Supporting Information Video S1: Epicardial propagation cines from non-invasive ECGi mapping demonstrating the activation sequences of the ventricles in intrinsic RBBB rhythm, during RV pacing, and during left bundle branch pacing. The cines show smooth rapid apex-to-base activation of the left ventricle during left bundle branch pacing, strongly suggesting conduction system capture. Author Contribution Statement MZ: primary author, drafted the manuscript, performed data collection and analysis, and prepared figures. AN: contributed to data collection and critical revision of the manuscript. IW: contributed to non-invasive mapping data acquisition and processing. NK: contributed to data interpretation and critical revision of the manuscript. AA: contributed to non-invasive mapping analysis and critical revision of the manuscript. ZW: contributed to study design, supervision, and critical revision of the manuscript. DK: conceived the study, supervised the work, performed the implantation procedure, and critically revised the manuscript. All authors reviewed and approved the final version of the manuscript. Independent Researcher Figure Legends Figure 1: (A) Presenting ECG with broad complex tachycardia suggesting an inferior focus within the RV. (B) ECG showing sinus rhythm with LBBB. (C) ECG shows a change to RBBB morphology following RBB ablation. (D) RV-paced ECG after permanent pacemaker implantation for CHB. Figure 2: (A) Posterior-anterior projection chest X-ray showing a septal RV lead close to the left bundle area pacing lead. (B) Lateral projection chest X-ray showing a more basal and posteriorly directed left bundle lead. (C) Preprocedural intrinsic ECG with RBBB morphology, with prolongation of the PR interval suggesting progression of the conduction system disease. (D) Left bundle area-paced ECG. Figure 3: Non-invasive mapping with ECGi showing epicardial activation patterns of the ventricles in intrinsic rhythm (top), during RV pacing (middle) and left bundle branch pacing (bottom). The colour time scales are individual to each pacing modality and are provided next to each set of maps. Abbreviations BVP, biventricular pacing; CHB, complete heart block; CSP, conduction system pacing; ECG, electrocardiogram; ECGi, epicardial electrocardiographic imaging; LBAP, left bundle area pacing; LBBB, left bundle branch block; LBBP, left bundle branch pacing; LV, left ventricle/ventricular; MRI, magnetic resonance imaging; RBBB, right bundle branch block; RV, right ventricle/ventricular; RVP, right ventricular pacing; VT, ventricular tachycardia. References 1. 1. Bednarek A, Kiełbasa G, Moskal P, Ostrowska A, Bednarski A, Sondej T, et al. Left bundle branch area pacing prevents pacing induced cardiomyopathy in long-term observation. PACE - Pacing and Clinical Electrophysiology. 2023;46(7). 2. Vijayaraman P, Sharma PS, Cano Ó, Ponnusamy SS, Herweg B, Zanon F, et al. Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Candidates for Resynchronization Therapy. J Am Coll Cardiol. 2023;82(3). 3. Jastrzębski M, Kiełbasa G, Cano O, Curila K, Heckman L, De Pooter J, et al. Left bundle branch area pacing outcomes: The multicentre European MELOS study. Eur Heart J. 2022;43(40). 4. Burri H, Jastrzebski M, Cano Ó, Čurila K, de Pooter J, Huang W, et al. 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). Europace. 2023;25(4). 5. Arnold AD, Shun-Shin MJ, Keene D, Howard JP, Chow JJ, Lim E, et al. Electrocardiographic predictors of successful resynchronization of left bundle branch block by His bundle pacing. J Cardiovasc Electrophysiol. 2021;32(2). 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Keyword cardiology Authors Affiliations Mohamed Zuhair 0000-0002-3678-1932 [email protected] Imperial College London National Heart and Lung Institute View all articles by this author Akriti Naraen 0000-0002-1681-2981 Imperial College London National Heart and Lung Institute View all articles by this author Ian Wright Imperial College Healthcare NHS Trust View all articles by this author Nandita Kaza Imperial College London National Heart and Lung Institute View all articles by this author Ahran D Arnold Imperial College London National Heart and Lung Institute View all articles by this author Zachary Whinnett Imperial College London National Heart and Lung Institute View all articles by this author Daniel Keene MbCHb MSc Imperial College London National Heart and Lung Institute View all articles by this author Metrics & Citations Metrics Article Usage 160 views 107 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Mohamed Zuhair, Akriti Naraen, Ian Wright, et al. 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