Catheter Ablation for Ventricular Fibrillation and Polymorphic VT Involving Proximal Purkinje in Structural Heart Disease: A Case Series

Catheter Ablation for Ventricular Fibrillation and Polymorphic VT Involving Proximal Purkinje in Structural Heart Disease: A Case Series | 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 Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed.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. 20 March 2025 V1 Latest version Share on Catheter Ablation for Ventricular Fibrillation and Polymorphic VT Involving Proximal Purkinje in Structural Heart Disease: A Case Series Authors : yuen hoong Phang 0009-0004-1475-154X , Ting-Yung Chang , and Chin-Yu Lin 0000-0003-3282-7523 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.174243814.40139050/v1 265 views 153 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Objective Ventricular arrhythmias originating from the upper ventricular septum have been described, but the involvement of the His-Purkinje System (HPS) remains underexplored. This study aims to characterize ventricular arrhythmias arising from the upper ventricular septum with HPS involvement and assess the role of catheter ablation in this patient population. Methods We retrospectively analyzed cases of VT ablation performed at Taipei Veterans General Hospital between 2018 and 2024. The study included patients with structural heart disease presenting with clinical polymorphic VT or VF and diseased HPS. Results Nine patients (78% male) with VT involving the HPS region were analyzed. The mean LVEF was 45.3 ± 10.5%, and the LVIDD was 53.5 ± 10.2 mm. Structural heart disease was ischemic in 5 patients (55%), dilated non-ischemic cardiomyopathy in 3 (33%), and valvular cardiomyopathy in 1 (11%). All patients had documented VF or unstable VT on ECG or device recordings. VT was inducible in all cases, with an average of 2.67 ± 1.15 VT morphologies per patient. Strategic Multielectrode Positioning (StaMP) mapping, late ventricular activation (LAVA) modification, and pace mapping for stable morphologies were applied. All arrhythmogenic areas were adjacent to diseased HPS. These strategies achieved non-inducibility of VT/VF in all patients. Post-ablation, conduction system injury occurred in all patients, manifesting as prolonged QRS duration or pacing dependency. One patient experienced recurrence, successfully managed with a repeat procedure. Conclusion Catheter ablation is a feasible treatment for unstable VT and VF in patients with structural heart disease. Achieving non-inducibility often necessitates ablation of the LV septum and opposing RV septum, albeit at the risk of conduction system injury and pacing dependency. These findings provide insights into ablation strategies for managing this complex patient population. Catheter Ablation for Ventricular Fibrillation and Polymorphic VT Involving Proximal Purkinje in Structural Heart Disease: A Case Series Yuen Hoong Phang 1,2 , Ting-Yung Chang 1,3 , Chin-Yu Lin 1,3 1 Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; 2 Division of Cardiology, Hospital Sultanah Bahiyah, Alor Setar, Malaysia 3 Cardiovascular Research Center, National Yang-Ming Chiao-Tung University School of Medicine, Taipei, Taiwan; Running title: Conflicts and Interest: none Address reprint requests and correspondence: Chin-Yu Lin, MD, PhD, Tel: 886-228712121 #89161 Heart Rhythm Center, Taipei Veterans General Hospital, No. 201 Shipai Rd, Section 2, Beitou District, Taipei 11217, Taiwan ( [email protected] ). Objective Ventricular arrhythmias originating from the upper ventricular septum have been described, but the involvement of the His-Purkinje System (HPS) remains underexplored. This study aims to characterize ventricular arrhythmias arising from the upper ventricular septum with HPS involvement and assess the role of catheter ablation in this patient population. Methods We retrospectively analyzed cases of VT ablation performed at Taipei Veterans General Hospital between 2018 and 2024. The study included patients with structural heart disease presenting with clinical polymorphic VT or VF and diseased HPS. Results Nine patients (78% male) with VT involving the HPS region were analyzed. The mean LVEF was 45.3 ± 10.5%, and the LVIDD was 53.5 ± 10.2 mm. Structural heart disease was ischemic in 5 patients (55%), dilated non-ischemic cardiomyopathy in 3 (33%), and valvular cardiomyopathy in 1 (11%). All patients had documented VF or unstable VT on ECG or device recordings. VT was inducible in all cases, with an average of 2.67 ± 1.15 VT morphologies per patient. Strategic Multielectrode Positioning (StaMP) mapping, late ventricular activation (LAVA) modification, and pace mapping for stable morphologies were applied. All arrhythmogenic areas were adjacent to diseased HPS. These strategies achieved non-inducibility of VT/VF in all patients. Post-ablation, conduction system injury occurred in all patients, manifesting as prolonged QRS duration or pacing dependency. One patient experienced recurrence, successfully managed with a repeat procedure. Conclusion Catheter ablation is a feasible treatment for unstable VT and VF in patients with structural heart disease. Achieving non-inducibility often necessitates ablation of the LV septum and opposing RV septum, albeit at the risk of conduction system injury and pacing dependency. These findings provide insights into ablation strategies for managing this complex patient population. Keyword : His-Purkinje System, ventricular fibrillation, polymorphic ventricular tachycardia, ablation, structural heart disease Introduction Clinical ventricular fibrillation (VF) and polymorphic ventricular tachycardia (VT) in patients with structural heart disease present significant management challenges. These arrhythmias frequently involve the Purkinje system, particularly in the presence of myocardial scarring or fibrosis. While catheter ablation has been shown to reduce morbidity, improve survival, and minimize implantable cardioverter-defibrillator (ICD) shocks in patients with recurrent monomorphic VT and idiopathic VF with Purkinje triggers, its role in polymorphic VT and VF associated with structural heart disease, particularly those involving proximal Purkinje structures, remains less well established. Substrate modification targeting low-voltage scars has emerged as a potential strategy for managing these complex arrhythmias 1-2 . However, this approach carries the risk of ablating non-clinical sites, potentially increasing recurrence rates. Additionally, when ablation involves the proximal Purkinje system, the likelihood of conduction system injury is heightened, particularly in patients with pre-existing conduction abnormalities, often leading to pacemaker dependency. This case series presents high-risk patients with structural heart disease undergoing catheter ablation for clinical VF and polymorphic VT involving the proximal Purkinje system. We evaluate the safety and efficacy of this approach in this challenging population. Methods Study Population We retrospectively analyzed cases of ventricular tachycardia (VT) ablation performed at Taipei Veterans General Hospital between 2018 and 2024. Nine patients with documented clinical ventricular fibrillation (VF) or polymorphic VT (PMVT) who underwent catheter ablation involving abnormal proximal Purkinje fibers were included. Baseline characteristics were thoroughly assessed. All patients provided written informed consent before the procedure. The study adhered to ethical standards, with data collection approved by the hospital’s human research committee. Echocardiography or cardiac magnetic resonance imaging was used to screen for structural heart disease and assess ventricular function. Myocardial ischemia was evaluated via coronary angiography or perfusion imaging. Ischemic cardiomyopathy (ICM) was diagnosed based on coronary artery disease confirmed by angiography or a history of prior myocardial infarction. Non-ischemic cardiomyopathy (NICM) was defined as persistent left ventricular (LV) systolic dysfunction in the absence of coronary artery disease, excluding conditions such as valvular heart disease, congenital heart disease, arrhythmogenic right ventricular cardiomyopathy, and cardiac sarcoidosis, which were independently evaluated. VF/PMVT episodes were distinguished from hemodynamically intolerant sustained monomorphic VT (SMVT) based on electrophysiologists’ evaluations, including retrospective analysis of electrocardiogram (ECG) tracings retrieved from implantable cardioverter-defibrillators (ICDs). Electroanatomic Substrate Mapping Electrophysiological studies were performed in a fasting state under conscious sedation or general anesthesia. Anti-arrhythmic drugs were continued due to VT storm. Electroanatomic mapping was conducted during sinus or paced rhythm using the CARTO® 3 Version 7.2 (Biosense Webster) or EnSite NavX (St. Jude Medical) systems. Ablation was performed with open-irrigated contact force-sensing catheters (Thermocool SmartTouch™ ST [Biosense Webster] or Tacticath™ SE [Abbott Medical]). Unipolar filtering was set at 2–240 Hz, and bipolar filtering at 16–500 Hz, with Wilson’s central terminal used as the unipolar reference electrode. Bipolar electrograms were recorded and stored digitally for offline analysis. Scar and low-voltage areas were defined by peak-to-peak bipolar voltage were defined by voltage <5.5 mV in the right ventricle and For non-spontaneous VT, rapid ventricular pacing and programmed stimulation with up to three extra stimuli were applied at the right ventricular apex. If VT remained non-inducible, intravenous isoprenaline (1–5 μg/min) was administered to achieve a heart rate increase of at least 20%. VT QRS morphologies were compared with documented VT morphologies. The LV endocardium was accessed via transseptal or retrograde transaortic approaches. Definition of Diseased Purkinje System In individuals with a normal His-Purkinje system, premature/extra stimuli can lead to bundle branch block, HV prolongation, and complete block, exhibiting physiologic properties in both antegrade and retrograde conduction. A diseased Purkinje system is postulated to result from ion channel alterations, increasing action potential duration 3 . The extent of these changes varies by etiology. Julie He and colleagues described common cellular mechanisms underlying these arrhythmias, including slow conduction allowing reentry, triggered activity, and enhanced automaticity 4 . VT Mapping and Catheter Ablation Induced VTs were analyzed for cycle length and morphology using the BARD LabSystem™ PRO EP Recording System. For hemodynamically tolerated VTs, entrainment pacing was performed at a cycle length 20–30 ms shorter than the tachycardia cycle length, with the response assessed. For hemodynamically unstable VTs, brief mapping was conducted using Strategic Multielectrode Positioning (StaMP), late ventricular activation (LAVA), or isochrone late activation mapping (ILAM), along with pacemapping. The procedure’s endpoint was the non-inducibility of VF/PMVT or non-sustained VT not requiring defibrillation. If VF/PMVT remained inducible post-ablation, mapping was performed in the opposite chamber to eliminate abnormal signals (Figure 1-4). Statistical Analysis Data are presented in tabular format where appropriate. Continuous variables are expressed as mean ± standard deviation (SD). Long-term arrhythmia-free survival is reported as VT recurrence over the follow-up period. A p-value <0.05 was considered statistically significant for all comparisons. Results Patient Characteristics Baseline patient characteristics are listed in Table 1. The mean age of the population was 68.9±5.6 years, with 7 males and 2 females. Documented VF was observed in 5 patients (63%), while 8 patients (89%) had polymorphic VT. Eight patients (89%) were in sinus rhythm, and one (11%) was pacing-dependent. Three patients (33%) had right bundle branch block (RBBB), two (22%) had intraventricular conduction delay (IVCD), two (22%) were pace-dependent with left bundle branch block (LBBB), and two (22%) had intact AV conduction. The mean QRS duration was prolonged at 157.1±35.0 ms. All patients had an intracardiac defibrillator, with one patient (11%) receiving cardiac resynchronization therapy. Echocardiographic parameters showed a mean ejection fraction (EF) of 45.38±10.50%, left atrial diameter (LAD) of 41.50±17.70 mm, left ventricular internal diameter in diastole (LVIDD) of 53.50±10.19 mm, and interventricular septal diameter (IVSD) of 9.50±2.12 mm. Cardiac MRI was not performed in some patients due to poor renal function, urgent ablations, or older devices. Among the five patients who underwent cardiac MRI, gadolinium enhancement was observed in three patients. LV thinning was noted in two patients. The mean right ventricular EF was 43.6±5.00%, and the mean left ventricular EF was 44.4±14.21%. Mapping of the VT Circuit A total of 23 VTs were induced, with a median of 2.67±1.15 VTs per patient (Table 2). The mean VT cycle length was 318.58±68.01 ms. VT morphologies included 12 (52%) left bundle branch block (LBBB) and 11 (48%) right bundle branch block (RBBB). Various axis orientations were noted. Complete VT mapping was achieved in 11 cases, with 3 VTs mapped using StaMP mapping. Unipolar and bipolar LV endocardial scars were identified in all patients, while unipolar and bipolar RV scars were present in 3 (33%) patients. Diseased His and proximal bundles were identified in 5 (56%) and 2 (22%) patients, respectively. Late potentials or LAVA were identified in 8 patients (89%). Ablation Outcomes Ablation rendered VT non-inducible in all patients (Table 3). LAVA elimination was the primary strategy, with additional pacemapping in one patient and potential PVC trigger elimination in two patients. AV block developed in 4 patients. One patient succumbed one month later due to sepsis. Excluding this case, the mean follow-up was 841.25±717.93 days, with one recurrence after four years. Five out of nine (55%) became pacing-dependent post-ablation. Discussion Findings and Strategy Our case series demonstrates that catheter ablation is a feasible and effective treatment for patients with documented ventricular fibrillation (VF) or polymorphic ventricular tachycardia (PMVT), with a low recurrence rate over a long follow-up period. Our primary strategy involved mapping low-voltage areas and utilizing the STAMP protocol to address unstable VT. Notably, our cohort consistently exhibited involvement of the upper septum and His-Purkinje system (HPS). The elimination of abnormal potentials and diseased fascicles rendered VT/VF non-inducible, which served as the procedural endpoint. Comparison with Literature The existing literature on catheter ablation in this challenging subgroup remains limited. Haïssaguerre’s initial 2002 study on His-Purkinje network VT/VF revealed that VF triggers originated from various locations within the Purkinje system and myocardium, and successful ablation achieved long-term freedom from recurrence 5 . Anderson’s subsequent work reinforced this, postulating that primary VF often arises from dominant triggers in the distal Purkinje system 6 . Similarly, our findings align with Nakamura’s approach, in which substrate modification targeting scar regions proved effective in the absence of identifiable PVC triggers 7 . Role of the Purkinje System The Purkinje system plays a pivotal role in arrhythmogenesis, acting as a driver of PMVT/VF through rapid burst activity. Earlier studies highlighted re-entry circuits involving the Purkinje-myocardial junction in the early stages of VF 8 . Beyond triggering arrhythmias, the Purkinje system significantly contributes to their maintenance. The interaction between the Purkinje system and myocardium influences the complexity and recurrence patterns of PMVT. These dynamics are crucial in both idiopathic and structural heart disease cases. Kocyigit et al. supported substrate modification as a strategy to suppress PMVT/VF by targeting potential re-entry circuits 9 . Guidelines and Future Directions Current guidelines classify catheter ablation for PMVT as a Class IIa recommendation for patients with frequent recurrences or electrical storms refractory to medical therapy 10-14 . However, these recommendations emphasize identifiable triggers or hemodynamically tolerated VT, which were absent in our cohort. We propose that a randomized controlled trial evaluating catheter ablation in this subgroup could provide stronger evidence for its efficacy. Timing of Ablation and ICD Placement While catheter ablation does not replace the role of an implantable cardioverter-defibrillator (ICD), its timing relative to ICD placement warrants discussion. Conventionally, ICD implantation is the first step in preventing sudden cardiac death, particularly in high-risk groups. However, in cases of incessant VT, VT storms, or identifiable triggers, early or concurrent catheter ablation may be warranted to reduce VT episodes and ICD shocks. In our cohort, the high risk of conduction system injury necessitated pre-procedural ICD placement or concurrent ICD implantation. Advances in conduction system pacing offer opportunities for substrate-guided lead placement, especially in patients with scarred left ventricles or diseased left bundle branches. Conclusion Catheter ablation of PMVT/VF is a viable and effective approach for patients with electrical storms. A subset of patients with diseased upper septal regions and His-Purkinje system involvement presents unique challenges, including a higher risk of conduction system injury. Pre-procedural ICD implantation or concurrent ICD placement is recommended for safety. Catheter ablation significantly reduces ICD shocks and hospitalizations, making it a valuable therapeutic option in this complex subgroup. Acknowledgement and funding This work was supported by the Biosense Webster IIS (C2304900), Ministry of Science and Technology (NSTC 113 - 2314 - B - 075 - 029 - MY3, NSTC 113 - 2628 - B - 075 - 003 - MY3, MOST 111-2314-B-075-007-MY3); and Taipei Veterans General Hospital (grant no. V113C-044, C19-027). Conflict of Interest Disclosure: The authors have no financial interest or relationship to disclose. Figure legend References 1. 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Heart Rhythm. 2019;16(1):e2-e38. doi:10.1016/j.hrthm.2018.10.001 13. Zeppenfeld K, Tfelt-Hansen J, de Riva M, et al. EHRA 2020 consensus document on the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Europace. 2020;22(6):1143-1145. doi:10.1093/europace/euaa106 14. Nair SG, Li X, Koide M, et al. Prevention of sudden cardiac death: APHRS 2022 consensus statement. Journal of Arrhythmia. 2022;38(2):170-192. doi:10.1002/joa3.12572 Supplementary Material File (table 1.docx) Download 16.16 KB File (table 2.docx) Download 16.44 KB File (table 3.docx) Download 14.86 KB Information & Authors Information Version history V1 Version 1 20 March 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords basic: ventricular tachycardia/fibrillation clinical: catheter ablation – ventricular tachycardia clinical: electrophysiology – conduction disturbances Authors Affiliations yuen hoong Phang 0009-0004-1475-154X Taipei Veterans General Hospital View all articles by this author Ting-Yung Chang Taipei Veterans General Hospital View all articles by this author Chin-Yu Lin 0000-0003-3282-7523 [email protected] Taipei Veterans General Hospital View all articles by this author Metrics & Citations Metrics Article Usage 265 views 153 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation yuen hoong Phang, Ting-Yung Chang, Chin-Yu Lin. Catheter Ablation for Ventricular Fibrillation and Polymorphic VT Involving Proximal Purkinje in Structural Heart Disease: A Case Series. Authorea . 20 March 2025. 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