2024 was an excellent year for the Journal of Cardiovascular Electrophysiology with a total of 389 original, high quality, peer-reviewed articles published. I am occasionally asked to identify the top papers published in JCE in the past year. A reasonable method to identify the top journal manuscripts during a particular period of time is based on the number of citations each paper has received. This is an objective approach. However, it is biased in favor of papers that were published earlier in the year giving more time for subsequent authors to cite the paper. With that understanding, here are the top five articles in JCE published in 2024 based on CrossRef citation data on the Wiley Online Library accessed January 13 th, 2025.

Department of CardiologyThe Prince Charles HospitalRode RdChermside Qld 4032AustraliaAuthor NoteConflicts of Interest: Institution received research funding for EV FIH study from Medtronic.Funding: NilORCID Number: 0000-0003-4819-6922Removal of EVICD leads are specialized tools required?Implantable Cardiac Defibrillators (ICDs) have improved the survival of patients at risk of sudden death and are widely indicated1]. Up until recently ICDs have been implanted transvenously and unfortunately been associated with a relatively high rate of lead complications during follow up 2. This often requires lead extraction which incurs some risk and is only available at specialized centers3. To overcome some of the limitations of the transvenous lead, Extravascular ICD (EVICD) systems have been developed over the last 15 years. First with a lead placed in the subcutaneous tissues above the sternum4and more recently in the retrosternal extravascular space above the pericardium 5 . Like all implantable cardiac devices these systems do fail and may require removal usually for either infection or lead related issues. Given the limited experience and the unique location of the EVICD lead in the retrosternal space the optimal management and risks associated with removal are still well defined.Sagi et al 6recently reported the largest clinical experience to date with removal of the EVICD lead from the retrosternal space. In 347 patients enrolled in three pre-market approval studies, lead removal was performed in twenty-nine patients at a mean of 12.6 months post implant. The overall success rate was 93.1%. (27/29). Leads with a dwell time of less than one year had a 100% success rate of removal (19/19) and required only simple traction in all cases. Leads with a dwell time of greater than 12 months had a lower success rate of 80% (8/10). Simple traction failed in six cases and extraction tools (laser or mechanical) were used in five cases with a success rate of 80%. One lead was abandoned. The longest dwell time for a successfully removed lead was 36.8 months. Importantly there were no procedural related complications.The paper by Sagi suggests that early removal of the EVICD lead within 12 months of implant is a safe and simple procedure requiring no more that simple traction. For leads longer than 12 months, however the optimal technique is still not clear and simple traction alone was not always successful. Delving into the reasons for failure of simple traction and the use of extraction tools, all appear to be related to the presence of dense adhesions at the sub xiphiod incision or diaphragmatic insertion area rather than the retro sternal space. This suggests that extensive dissection along the lead body to the level of the diaphragmatic insertion may be required before an extraction tool is used. Furthermore, if an extraction tool is used it is likely to be particularly important that the lead and tool be always kept coaxially. The angulation often seen as the lead passes under the sternum may result in the extraction tool damaging the outer insulation, which will cause significant weakening of the tensile strength of the lead which may result in it breaking and failure of removal. In the series by Sagi et al the longest dwell time was 58 months, and this lead was not successfully removed. The premature use of both a laser sheath and mechanical tool to assist the removal procedure, prior to adequate dissection of the sub diaphragmatic space resulted in disruption of the outer insulation, loss of tensile strength and subsequent breaking of the lead which left 6.4 cm remaining in situ. It should be noted the EVICD lead, unlike traditional transvenous leads, is lumenless and hence a locking stylet cannot be used to create a rail and assist with use of extraction tools.In this issue of the journal two case reports from Chauhan7 and de Veld [8] extended the dwell times of EVICD leads successfully removed to 43 and 49 months, respectively. In both reports, the leads were removed with simple traction after the suture sleeve was released and dissection was performed along the lead towards the sub diaphragmatic surface. Both these cases highlight the importance of adequate dissection in the sub diaphragmatic space as most adhesions associated with this lead appear in this region rather than the retrosternal space. It may be best to avoid the use of extraction tools which are not design for the lumenless EVICD lead until adequate dissection has been performed The premature use of the tools prior to adequate dissection of the sub diaphragmatic space may in fact hinder the removal of the lead due to disruption of the outer insulation and loss of tensile strengthThese reports add to the evidence suggesting these leads can be removed safely with simple techniques at a medium term follow up of 4 years, while this is reassuring it must be remembered the experience with removal of these leads is still small and with short dwell times. It is reassuring that the site of all adhesions to date appear to be in the sub xiphiod and sub diaphragmatic space rather than the retrosternal space. Hopefully, this means potentially more serious complications related to cardiac injury during lead removal from adhesions related to the pericardium remain rare. The optimal personnel to perform this procedure (electrophysiologist or cardiac surgeon), location (EP lab or operating room) and even the need for pre removal imaging if any is still not clear. Will leads with dwell times of 10 years or more be as easy to remove. These are all unknowns at present and the answers will only become clearer as the experience grows. For the time being the removal of these leads, especially if older than 12 months, should probably continue to be undertaken, by cardiac teams experienced in implanting the device with a good understanding of the sub diaphragmatic space. With adequate dissection of the lead, transvenous lead extraction tools may be rarely required. To date there continues to be no procedural complications reported with removal of the EVICD lead and with time this may prove to be yet another advantage of the EVICD over traditional transvenous ICD even when implanted in the novel retrosternal space.References1. Zeppenfeld K, Tfelt-Hansen J, De Riva M, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J . 2022;43(40). doi:10.1093/eurheartj/ehac2622. Koneru JN, Jones PW, Hammill EF, Wold N, Ellenbogen KA. Risk factors and temporal trends of complications associated with transvenous implantable cardiac defibrillator leads. J Am Heart Assoc . 2018;7(10). doi:10.1161/JAHA.117.0076913. Bongiorni MG, Kennergren C, Butter C, et al. The European Lead Extraction ConTRolled (ELECTRa) study: A European Heart Rhythm Association (EHRA) Registry of Transvenous Lead Extraction Outcomes.Eur Heart J . Published online 2017. doi:10.1093/eurheartj/ehx0804. Bardy GH, Smith WM, Hood MA, et al. An Entirely Subcutaneous Implantable Cardioverter–Defibrillator. New England Journal of Medicine . Published online 2010. doi:10.1056/NEJMoa09095455. Friedman P, Murgatroyd F, Boersma LVA, et al. Efficacy and Safety of an Extravascular Implantable Cardioverter–Defibrillator. New England Journal of Medicine . 2022;387(14). doi:10.1056/nejmoa22064856. Sagi V, Murgatroyd F, Boersma LVA, et al. Comprehensive analysis of substernal lead removal: experience from EV ICD Pilot, Pivotal, and Continued Access Studies. Europace . Published online August 30, 2024. doi:10.1093/europace/euae2257. Chauhan K, Royse A, Goh I, Crozier I, Wynn G. Oldest-in-Human Successful Extraction Experience of a Novel Substernal Extravascular Defibrillator. J Cardiovasc Electrophysiol . Published online November 22, 2024. doi:10.1111/jce.165118. de Veld J, Kooiman K, Knops. Uncomplicated extravascular implantable cardioverter extraction after four years dwell time: a case report. J Cardiovasc Electrophysiol

Integrating mapping and 4D ultrasound – is this the dawn of a new ICE age?Rachel M. Kaplan, MD, MS, FHRSIntracardiac echocardiography (ICE) is routinely used by electrophysiologists in the United States for numerous procedures. ICE provides visualization of anatomic structures and can be used to guide ablation lesions. Integration with mapping expands the utility of ICE to also facilitate acquisition of anatomic geometry and aid in identifying structures of interest such as coronary arteries.In the past few years, multiple companies have developed 4D ICE catheters which have elevated the range of imaging obtainable with ICE to be more similar to modern transesophageal echocardiography (TEE). These catheters can obtain multiplanar imaging which enables 3D views in real time and can reduce the need for ICE catheter manipulation to obtain multiple views1.The use of 4D ICE is increasingly described for LAAO, primarily because it can substitute for TEE. Multiple studies have shown comparable outcomes between ICE guided and TEE guided LAAO, though some have shown higher rates of pericardial effusions with ICE2-4. Reduced need for catheter manipulation in the left atrium with 4D ICE catheters may help mitigate this risk. The benefit of utilizing 4D ICE in ablation procedures is less clear. Beyond the technologic intrigue, multiplanar and 3D imaging is not typically required in ablations5. However, integration with mapping has the potential to utilize these additional imaging features for benefit in ablation procedures.In this issue of JCE, Blumenthal et al . describe a pre-clinical study of the use of a 4D ICE catheter with mapping integration in swine models6. The NuVision 4D ICE catheter (Biosense Webster) provides real-time 3D ultrasound imaging and integrates with CARTO anatomic mapping (CARTOSOUND, Biosense Webster). They demonstrated rapid acquisition of geometry by using CARTOSOUND with the 4D ICE catheter where multiplane imaging acquires two 2D images with each position. Furthermore, 360-degree imaging can be obtained without moving the catheter itself. Additionally, ICE provides real time visualization during cardiac motion which can show the operator how the ablation catheter is moving on a structure such as the papillary muscles, therefore improving catheter stability.There are a few drawbacks to 4D ICE. The catheters are slightly larger which then require larger bore vascular access and higher risk of vascular complications. The biggest concern, however, is cost. These catheters cost significantly more than standard 2D ICE catheters. Cost-effectiveness of 2D ICE has been described for LAAO procedures where it has been shown to be comparable to TEE for overall costs (counting both equipment and professional services)7. However, studies comparing 4D to 2D ICE for LAAO have shown that the 3D images are more comparable to TEE with regards to sizing of the LAAO device8. Demonstrating cost-effectiveness of 4D ICE for ablation procedures will be more complex. Future studies will need to investigate effects on procedure duration, risk of complications, or even procedure efficacy (perhaps for papillary muscle premature ventricular contractions where stability can be difficult). Unfortunately, until cost effectiveness demonstrates tangible benefits to 4D ICE in ablations, these catheters may be relegated to selective and investigational use in most hospitals.One niche area for a mapping-integrated 4D ICE catheter may be concomitant atrial fibrillation ablation with LAAO because ICE is typically used in the United States for atrial fibrillation ablation. Use of 4D ICE can enable the entire case to be performed without needing to use TEE for the LAAO part. This also avoids the requirement for a TEE trained imaging physician to be available for the procedure. An example of an LAAO device implant under 4D ICE guidance with the NuVision catheter is shown in the Figure. In this case, the patient underwent pulmonary vein isolation with the ICE catheter in the right atrium, then the NuVision ICE was advanced into the left atrium to guide the implantation of a Watchman device (Boston Scientific). In such cases, the added cost of a 4D ICE catheter compared to a 2D ICE catheter can be offset by not needing the expense of TEE or TEE trained physicians. Imaging with 4D ICE catheters requires advanced knowledge of the imaging console which is often provided by representatives from the ICE catheter company. However, such costs are borne by the whole healthcare industry rather than attributed to an individual procedure by the hospital.Mapping integrated 4D ICE is a technologically exciting forward step though its utility in ablation procedures has yet to be established. Cost concerns will likely limit its broad adoption but it may provide benefits in specific complex ablation cases or perhaps in concomitant ablations with LAAO.1. Adams A, Mahmood R, Balaji N, Dixit P, Chandra S, Weisman D. Real-world experience utilizing the nuvision 4D intracardiac echocardiography catheter for left atrial appendage closure. Sci Rep. 2024;14(1):11937.2. Ferro EG, Alkhouli M, Nair DG, et al. Intracardiac vs Transesophageal Echocardiography for Left Atrial Appendage Occlusion With Watchman FLX in the U.S. JACC Clin Electrophysiol. 2023;9(12):2587-2599.3. Serpa F, Rivera A, Fernandes JM, et al. Intracardiac vs transesophageal echocardiography for left atrial appendage occlusion: An updated systematic review and meta-analysis. Heart Rhythm. 2024.4. Diaz JC, Bastidas O, Duque M, et al. Impact of intracardiac echocardiography versus transesophageal echocardiography guidance on left atrial appendage occlusion procedures: A meta-analysis. J Cardiovasc Electrophysiol. 2024;35(1):44-57.5. Kaplan RM, Narang A, Gay H, et al. Use of a novel 4D intracardiac echocardiography catheter to guide interventional electrophysiology procedures. J Cardiovasc Electrophysiol. 2021;32(12):3117-3124.6. Blumenthal C, Hsue W, Chen T, Zhang D, Brem E, Garcia F, Callans DJ, Marchlinski FE, Santageli P, Tschabrunn CM. Pre-Clinical Experience using 4D ICE to Guide Ablation and Structural Procedures of Complex Intracavitary Structures. Journal of Cardiovascular Electrophysiology. 2024.7. Alkhouli M, Chaker Z, Alqahtani F, Raslan S, Raybuck B. Outcomes of Routine Intracardiac Echocardiography to Guide Left Atrial Appendage Occlusion. JACC Clin Electrophysiol. 2020;6(4):393-400.8. Della Rocca DG, Magnocavallo M, Gianni C, et al. Three-dimensional intracardiac echocardiography for left atrial appendage sizing and percutaneous occlusion guidance. Europace. 2023;26(1).Figure

not-yet-known not-yet-known not-yet-known unknown A 57-year-old woman with frequent palpitations was referred for radiofrequency ablation. The baseline 12-lead electrocardiogram and echocardiography were normal. The baseline atrio-His (AH) and His-ventricular (HV) intervals were 70 and 35 ms, respectively. Dual atrioventricular (AV) nodal physiology was not observed during programmed atrial stimulation. Ventriculoatrial conduction showed a decremental and concentric pattern, with the earliest atrial activation recorded in the His bundle region. There was no evidence of a jump-up phenomenon during programmed ventricular stimulation. Supraventricular tachycardia (SVT) with variable AH and His-atrial (HA) intervals was induced by extra atrial stimulation without any jump-up in the AH interval. The earliest atrial activation during SVT was recorded at the coronary sinus (CS) 7,8 region, corresponding to the CS ostium, which differed from the atrial activation sequence during ventricular pacing. The atrial-atrial (AA) intervals demonstrated variability exceeding 50 ms without any alteration in the atrial activation sequence (Figure 1A). Ventricular entrainment pacing was performed during SVT (Figure 1B). Transient 2:1 AV conduction was observed during SVT (Figure 1C). Based on these findings, what is the mechanism of the variability in the AA, AH, and HA intervals during tachycardia?

Exploring S-ICD Extraction rates and frequency in modern PracticeMoied M. Al Sakan MD, Marwan M. Refaat, MDDivision of Cardiology, Department of Internal Medicine, American University of Beirut Medical Center, Beirut, LebanonRunning Title: S-ICD ExtractionWords: 620 (excluding the title page and references)Keywords: subcutaneous, Implantable cardioverter-defibrillator, cardiac arrhythmias, cardiology, cardiovascular diseases, extractionFunding: NoneDisclosures: NoneCorresponding Author:Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FRCPTenured Professor of MedicineTenured Professor of Biochemistry and Molecular GeneticsMember, Division of Cardiology/ Section of Cardiac ElectrophysiologyDirector, Cardiovascular Fellowship ProgramAmerican University of Beirut Faculty of Medicine and Medical CenterPO Box 11-0236, Riad El-Solh 1107 2020- Beirut, LebanonUS Address: 3 Dag Hammarskjold Plaza, 8th Floor, New York, NY 10017, USAOffice: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct)The subcutaneous implantable cardioverter defibrillator (S-ICD) represents a significant advancement in the management of patients at risk for lethal arrhythmias and sudden cardiac death, particularly those not expected to have a need for pacing. This technology offers a compelling alternative to traditional transvenous ICDs (TV-ICDs), especially in young patients with a long-life expectancy, normal heart, and no need for pacing or cardiac resynchronization therapy, at increased risk of infections and with limited vascular access.[1] This study by Arati Gangadharan et al in the Journal of Cardiovascular Electrophysiology sheds light on an important aspect of S-ICD management, which is the extraction rates and indications for S-ICD extraction.[2]In this retrospective analysis of 372 patients undergoing S-ICD implantation between 2010 and 2022, the authors reported an extraction rate of 5.9% over a median follow-up period of 4.4 years. This figure falls within a spectrum of previously reported extraction rates, highlighting a notable variability across studies. What was notable is the importance of smoking and obesity as independent associations with increased S-ICD extraction. This study focused primarily on key indications of S-ICD extraction such as the need for bradycardia pacing, inappropriate shocks due to oversensing, infection and cardiac transplantation. Additional non-infectious indications have been reported such as lead rupture (2.42%), sensing issues (4.35%) and patient discomfort (2.42%). [1] When comparing the indications for lead extraction between this study and the indications noted in the systematic review on S-ICD lead extraction by Riccardo Vio et al, spanning the same period (articles collected until 2022), we can note similarities between the two studies (inappropriate shocks, infection, and the need for cardiac resynchronization therapy) but also other indications included defibrillation threshold testing failure (2.42%), lead malposition (1.93%), and premature battery depletion (0.48%). [1] Cardiac implantable electronic devices has been shown to be of benefit in patients with severe cardiomyopathy. [3,4] Also, when looking at the indications for S-ICD implantation- one of the most common indications for S-ICD implantation was primary prevention in patients with heart failure with reduced ejection fraction, Univariate analysis demonstrated that a history of lower left ventricular ejection fraction (P=<0.001), was associated with S-ICD extraction. (2,5) Notably, this study shed some light on the independent associations with a history of smoking and elevated body mass index (BMI) which serve as important factors that clinicians should consider during the pre-implantation assessment. These findings corroborate existing sparse literature suggesting that obesity and smoking may complicate device function and patient outcomes (2,5-7).The observational design from a single center limit the generalizability of these results to other populations. Future studies incorporating larger, multicenter cohorts also considering the socioeconomic status could provide more definitive insights.[2]In conclusion, while the S-ICD is generally preferred over TV-ICD in appropriately selected patients, the findings from this study highlight the necessity for meticulous pre-implantation assessments and the recognition of specific risk factors that may influence the risk of device extraction. As electrophysiology advances, combining the subcutaneous ICD (S-ICD) with a leadless pacemaker could shift the S-ICD toward becoming the preferred device choice, particularly for patients who would benefit from both defibrillation and pacing functions.[8] Furthermore, as suggested by the authors, the development of S-ICD technology and evolving guidelines over the last ten years may have affected the clinical decision-making process regarding device extraction and implantation as well as the rates of complications.[9]In summary, the results of this study emphasize the need for thorough pre-implantation evaluations and the identification of particular risk factors that may affect the risk of device extraction, even if the S-ICD is typically preferred over the TV-ICD in some patients.[2] The growing use of S-ICDs in a variety of patient populations necessitates continuous assessment of their safety and efficacy, especially when new technologies and indications are developed.

Atrial fibrillation (AF) is the most common sustained arrhythmia. While the primary treatment concern with AF is the managing the risk of thromboembolism, AF can also cause significant symptoms in some patients and be completely asymptomatic in others (1). Many patients with AF have debilitating symptoms including palpitations, heart failure, and anxiety. It is well known that patients can have some symptomatic AF episodes and others that are asymptomatic (2). In this issue of the Journal of Cardiovascular Electrophysiology, a study by Ahluwalia et al. attempts to assess factors associated with symptomatic AF episodes in patients with insertable cardiac monitors (ICM).In this retrospective observational study, the authors examined 11,267 patients with a Reveal LINQTM ICM in the DiscoveryLink from 2007 to 2021. These patients all had episodes of AF detected by the ICM’s detection algorithm, and the patient’s clinical data was obtained from the Optum® de-identified electronic health record. The AF episodes were not adjudicated, and the symptoms were not verified.Asymptomatic AF was far more common than symptomatic episodes. Only 15.8% of patients had a device reported AF symptom. In addition, of the 380,625 episodes of automatically detected AF, only 6190 episodes (1.63%) had a symptom activation within 20 minutes. The symptomatic AF patients were younger (67±12 years vs. 71±11 years old), more female (51% vs 43%), and had less cardiovascular diagnoses. In addition, AF episodes with a symptom activation, were longer in duration (5.5 hrs vs. 3.7 hrs), had a higher ventricular rate (103 bpm vs. 88 bpm), and had a higher AF evidence score (more likely to be true AF per the device-based algorithm)These findings are similar to other reports about AF detections, especially device detected AF, but have extended them to a large cohort of patients with ICMs, with clinical and symptom data. The most important takeaway is that screening for AF needs to go far beyond evaluation for symptoms as most AF episodes are not symptomatic, and in patients with symptomatic AF, the episodes of AF are just the tip of the iceberg of AF burden. Symptoms were associated with a higher AF evidence score, indicating the symptoms could be used to help differentiate a true AF detection, from a false positive which could help guide clinical management. Also AF symptoms seemed to be more common in younger, less comorbid, and female patients, which is consistent with other published data (1). This does highlight one paradoxical finding, that females seem to be more symptomatic with AF, but less likely to be offered ablation.The primary limitation of this study is the retrospective observational nature of the data. It is unclear why the patients pushed the symptom activator. The symptom activation could have been for palpitations, another AF related symptoms, or purely accidental. It is not known what instructions the patients received to activate the symptom activator, and what percentage of patients knew how to actually use it properly. Also given the nature of the handheld device to mark symptoms, it is likely that many patients did not activate the ICM for every symptom either to due to symptom fatigue, or inability to access the activator at the time of an episode. Some of these limitations could be overcome with a prospective cohort educated in using the ICM to track AF symptoms, and the newer app-based symptom activators. Since the AF episodes were not adjudicated, it is unclear if some of the symptom episodes were related to false AF detections. Another useful piece of information from this data would be the number of symptom activations that were not related to an arrhythmia.However, this study does give an insight into a large cohort of patients with AF and ICMs. This data could help spur future research into how to properly assess for AF symptoms, and how to minimize AF symptoms.Sgreccia D, Manicardi M, Malavasi VL, Vitolo M, Valenti AC, Proietti M, Lip GYH, Boriani G. Comparing Outcomes in Asymptomatic and Symptomatic Atrial Fibrillation: A Systematic Review and Meta-Analysis of 81,462 Patients. Journal of Clinical Medicine. 2021; 10(17):3979. https://doi.org/10.3390/jcm10173979Quirino G, Giammaria M, Corbucci G, Pistelli P, Turri E, Mazza A, Perucca A, Checchinato C, Dalmasso M, Barold SS. Diagnosis of paroxysmal atrial fibrillation in patients with implanted pacemakers: relationship to symptoms and other variables. Pacing Clin Electrophysiol. 2009;32:91-98. https://doi.org/10.1111/j.1540-8159.2009.02181.x

A document by Matthew Bennett. Click on the document to view its contents.

Response to letter re: ‘Premature Ventricular Complexes after Catheter Ablation for Atrial Fibrillation: Accounting For Regression to the Mean’William Whang, MD1 and Alex Choy, MD21Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY; william.whang@mountsinai.org2Department of Medicine, University of Chicago, Chicago, IL; a.choy10@gmail.comCorresponding author: William Whang, MD (william.whang@mountsinai.org)One Gustave Levy PlaceNew York, NY 10029212-241-7114We thank Dr. Wang for his interest in our research letter. He questions whether the endpoint used in our study, frequency of premature ventricular complexes (PVC) as a percentage of total complexes measured pre- versus post-ablation, is a valid indicator due to the skewed distribution and lack of granularity. Although we did not use absolute number of PVCs per day from a 24-hour Holter for our endpoint, we would argue that PVC percentage is a valid indicator of arrhythmia burden that has been associated in a dose-dependent manner with outcomes such as cardiomyopathy and mortality in cohorts such as the community-based Cardiovascular Health Study.1 In addition, in our study the median duration of monitoring (6 days) was longer than in prior studies of atrial fibrillation (AF) ablation and PVCs. A recent study that used commercially available event monitors concluded that longer monitoring periods resulted in significantly reduced mean measured error of PVC burden.2We sought to approach the measure for significant PVC burden (≥1000/day) mentioned by Dr. Wang, with a proxy threshold of ≥1% PVCs. In our sample 21.5% of patients had ≥1% PVCs pre-ablation and 19.2% had ≥1% PVCs post-ablation (p=0.76, chi-squared test), again suggesting lack of significant association between AF ablation and PVC burden. We agree with Dr. Wang that prospective studies would be worthwhile to assess the true impact of AF ablation on PVCs, and would stress that inclusion of samples unrestricted by PVC burden pre-ablation could help clarify this question.1. Dukes JW, Dewland TA, Vittinghoff E, Mandyam MC, Heckbert SR, Siscovick DS, Stein PK, Psaty BM, Sotoodehnia N, Gottdiener JS, Marcus GM. Ventricular Ectopy as a Predictor of Heart Failure and Death.Journal of the American College of Cardiology . 2015;66:101–109. 2. Krumerman A, Di Biase L, Gerstenfeld E, Dickfeld T, Verma N, Liberman L, Amara R, Kacorri A, Crosson L, Wilk A, Ferrick KJ. Premature ventricular complexes: Assessing burden density in a large national cohort to better define optimal ECG monitoring duration. Heart Rhythm . 2024;21:1289–1295.

Challenges in Cardiac Implantable Electronic Device Surveillance: Insights from Real-World DataGeorge S. Prousi, MD and Pamela K. Mason, MDUniversity of VirginiaCorresponding author:Pamela K. Mason, MDBox 800158Charlottesville, VA 22908434-924-2465Fax: 434-982-1998Pkm5f@virginia.eduDisclosures:Mason- Consulting and honoraria for Medtronic and Boston ScientificProusi- NoneCardiac implantable electronic devices (CIEDs), including permanent pacemakers (PPMs), implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) devices have improved patient outcomes for a variety of cardiovascular conditions.1,2 There is an upward trend in the utilization of CIEDs due to multiple variables including an aging population with increased comorbidities and expanded indications.3 CIED technology has rapidly evolved and device components must undergo rigorous evaluation to ensure safety and efficacy. Despite pre-market testing and post-market surveillance, historically, there has been an underestimation of device and lead failures.4 It is well known that transvenous leads are the “weak link” in most CIED systems, and efforts to reduce CIED malfunctions must address this issue.To improve the reliability of transvenous leads, design and manufacturing has included a focus on insulation integrity. Optim™, a co-polymer of silicone and polyurethane is a form of insulation incorporated into the Abbott Tendril™ STS 2088TC (Tendril 2088) leads. It was developed with an aim to reduce the risk of lead abrasion. There have been several studies suggesting an accelerated degradation of materials and lead failure for leads using Optim™, and particularly the Tendril 2088 lead.5-7 However, most of the clinical studies are single-center and observational.In this edition of the Journal of Cardiovascular Electrophysiology, Ahmed et al. used an analytic real-world data model to compare the Tendril 2088 lead to pacing leads manufactured by competitors. This model uses patient device tracking, the Abbott device registration database, and the Medicare-fee-for-service database, and it has been validated previously.8 Probablistic linking was used to link the patients who were implanted with Tendril 2088 leads from the Abbott registry to the Medicare database. The authors then compared the rates of Tendril 2088 mechanical lead malfunction resulting in lead-related surgical intervention to competitors’ pacing leads. The numbers are substantial, with 89,629 Tendril 2088 leads identified compared to 433,481 competitive manufacturer leads. The groups were demographically similar, and the follow-up period was a minimum of two years. This real-world data analysis revealed no significant difference in surgical intervention-free survival rates between the two groups.The findings of this study present a contrast from other studies that suggested that there may be an increased risk of Tendril 2088 lead failures as compared to competitors’ pacing leads. The authors outline potential reasons for this variance, which include sample size, possible bias within the populations, and how “lead failure” is defined. This study had a rigorous definition of failure which needed surgical intervention but may not completely reflect all failure presentations and the effect on patient outcomes. This serves as a reminder of the challenges in product evaluation and surveillance.The authors have offered important insights into the Abbott Tendril 2088 lead, although evaluation of the Tendril 2088 lead and the Optim™ insulation will be ongoing.7 They also should also be congratulated for showing the added value of a real-world data model in post-market product monitoring. With these models, sample sizes can more accurately and expeditiously identify occurrences of device related malfunction and capture a wider range of patient demographics.Device manufacturers and the electrophysiology community are continually developing ways to analyze and follow products for safety and reliability. It is clear that the traditional methods of pre-market studies and post-market registries are inadequate to identify product deficiencies. This is particularly true for more uncommon issues or ones that only occur in specific populations or circumstances. Manufacturers are adding simulation modeling data to their product evaluation to enhance the reliability of their data.9 The addition of real-world data is another substantial advancement.It is important to note that many CIED manufacturers are making efforts to move away from traditional stylet-driven transvenous leads.10 This is a simple acknowledgement that these leads are still the “weak link” in most device systems despite sophisticated engineering and aggressive surveillance. Lumen-less transvenous leads are available which are thought to be more durable. For ICDs, subcutaneous and extravascular leads are both lumen-less and do not use the vasculature. Finally, leadless pacemakers avoid the issue all together.Regardless of these advances, millions of patients have transvenous CIED systems in place and these systems will continue to be the major mode of providing CIED therapies into the near future. We need robust mechanisms to follow all CIED products and real-world data models will play a role. Though there will be further question about the reliability of Tendril 2088 leads, there should be no dispute over the united pursuit for early identification of device related malfunctions and the use of large-scale data to achieve the best possible outcomes for our patients.Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: Executive summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. Heart Rhythm. 2019;16:e227-e279.Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2018;72:e91-e220.Greenspon AJ, Patel JD, Lau E, et al. . Trends in permanent pacemaker implantation in the United States from 1993 to 2009: increasing complexity of patients and procedures. J Am Coll Cardiol. 2012;60:1540-5.Roberts H, Matheson K, Sapp J, et al. Prevalence and management of electrical lead abnormalities in cardiac implantable electronic device leads. Heart Rhythm O2. 2023;4:417-426.Segan L, Samuel R, Lim M, et al. Incidence of Premature Lead Failure in 2088 TendrilTM Pacing Leads: A Single Centre Experience. Heart Lung Circ. 2021;30:986-9956.Shah AD, Hirsh DS, Langberg JJ. User-reported abrasion-related lead failure is more common with durata compared to other implantable cardiac defibrillator leads. Heart Rhythm. 2015;12:2376-80.El-Chami MF. The saga of tendril leads continues: Should we continue to bury our heads in the sand? J Cardiovasc Electrophysiol. 2021;32:1122-1123.Braghieri L, Ahmed A, Curtis AB, et al. Evaluating cardiac lead safety using observational, real-world data: EP PASSION proof-of-concept study. Heart Rhythm. 2024;S1547-5271(24)02819-4.Crossley, George H.Sanders, Prashanthan et al. Safety, efficacy, and reliability evaluation of a novel small-diameter defibrillation lead: Global LEADR pivotal trial results 2024;S1547-5271(24)02395-6.Wiles BM, Roberts PR. Lead or be led: an update on leadless cardiac devices for general physicians. Clin Med (Lond). 2017;17:33-36.

This paper explores the innovative approach of cardiac calcium electroporation as a potential advancement in catheter ablation techniques, building upon the historical context of thermal ablation methods. While traditional radiofrequency and cryothermal ablation have significantly improved efficacy and safety, the risk of collateral damage persists. Pulsed-field ablation (PFA) has emerged as a promising non-thermal alternative designed to target cardiac myocytes while sparing adjacent tissues. However, concerns about unintended consequences remain. In this study by Toya et al., the efficacy of low-power PFA augmented with calcium chloride infusion resulted in enhanced lesion formation, with increased surface area, volume, and histological damage, suggesting a potential for improved targeted ablation. Despite these findings, the study acknowledges limitations, including a small sample size and the need for further investigation into calcium’s effects on lesion durability and safety. This exploration represents a nascent step toward redefining cardiac ablation practices, highlighting the possibility of enhanced therapeutic and safety outcomes through innovative strategies. As PFA continues to evolve, incorporating calcium electroporation may further separate the overlapping risks of effective tissue ablation from collateral damage, signaling a transformative shift in cardiac electrophysiology.

Introduction: Substernal extravascular defibrillators (EV ICDs) have been shown to be effective and safe for patients at risk of sudden cardiac death, however, there is little evidence around the safety of extracting chronic devices. Methods and Results: We present a 50-year-old patient in whom a Medtronic EV ICD system was successfully removed without specialist extraction tools, 186 weeks after implantation, by an operator experienced in transvenous lead extraction but without formal training in EVICD implantation. Conclusion: The successful extraction of an EV ICD system is possible without specialised tools at least 3.6 years post-implant.

Understanding Differential Pacing: Unraveling the pitfalls of base vs apex pacing in distinguishing AVNRT from AVRT over a septal APPavel Antiperovitch1, Ahmed Mokhtar2, George Klein1Western University, Department of MedicineDepartment of Medicine, King Abdulaziz University, Jeddah, Saudi ArabiaWord Count : 552Abbreviations :AVNRT: Atypical Atrioventricular Nodal Reentrant Tachycardia, AVRT: Atrioventricular Reentrant Tachycardia, AP: Accessory Pathway, AV: Atrioventricular, CS: Coronary Sinus, PPI-TCL:, Post-Pacing Interval – Tachycardia Cycle Length, RA: Right Atrium, RBB: Right Bundle Branch, RV: Right Ventricle, SVT: Supraventricular Tachycardia, VA: Ventriculo-Atrial, VOP: Ventricular Overdrive PacingThe article “Differential Ventricular Overdrive Pacing During Long RP’ Supraventricular Tachycardia: How Can We Interpret?” by Nakashima et al1provides some reflection on a widely used differential pacing maneuver. The authors present a case of long RP supraventricular tachycardia, where right ventricular (RV) entrainment excluded atrial tachycardia. Following adenosine administration, there was AH prolongation and a block to the RV while the tachycardia persisted, indicating that neither the AH interval nor the RV were part of the reentrant circuit. The authors conclude that the most likely diagnosis is atypical AV nodal reentrant tachycardia (AVNRT). To further explore this, the authors conducted ventricular overdrive pacing (VOP) from both the base and apex of the RV. They observed that entrainment from the RV base resulted in a shorter VA interval and a smaller PPI-TCL compared to the apex. This finding supports the presence of an AV pathway, which contradicts earlier diagnostic assessmentsDifferential pacing is a widely used technique to distinguish between nodal and extranodal ventriculo-atrial (VA) conduction via an accessory pathway.² In this case, why did the standard maneuver fail? The authors suggest that inadvertent His bundle capture was the reason, as indicated by the narrower paced QRS on the surface ECG when pacing close to the base. This issue can be avoided by repositioning the pacing electrode away from the His bundle or adjusting the pacing output. Another common pitfall in differential pacing is the location of the second pacing site. The traditional second pacing site is the apical region, which is a surrogate for approximating the site of the right bundle branch (RBB) exit into the RV. However, identifying the apex on fluoroscopy or a mapping system is subjective and probably poorly reproducible between patients and operators, leading to inconsistent distances of the recording catheter to the RBB terminus .To overcome these issues, we propose a slight shift of focus away from the conventional “apex” and “base” approach to a more reproducible physiological concept that is familiar to every electrophysiologist: the line of block. The atrioventricular (AV) plane of the heart serves as a natural line of block, and any conduction gaps other than the normal AV conduction system along this plane represent AV pathways. The operator’s goal is to test for completeness of the line of block by pacing close to and at a fixed distance from the AV ring (Figure 1). The first pacing site is positioned as close as possible to the annulus, typically in the posteroseptal RV just beyond the coronary sinus (CS) ostium, to reduce the risk of capturing the conduction system or atrium. The second site is placed a few centimeters farther away from the base moving inferiorly. Very simply, moving inferiorly a short distance from the annulus must shorten the SA interval if the “line of block” is complete (i.e. no septal pathway) and lengthen if there is no block (i.e. a septal AP). This approach removes the need to locate the true apex, at best an imprecise surrogate for the RBB exit into the RV, and reframes differential pacing in terms familiar to every electrophysiologist—it’s grounded in the fundamental principles we apply daily in the lab. It also sheds light on the common pitfalls of the maneuver, which are akin to those encountered when testing for gaps along ablation lines.REFERENCES1. Nakashima T, Nagase M, Usui T, et al. Differential ventricular overdrive pacing during long-RP supraventricular tachycardia: How can we interpret?Journal of Cardiovascular Electrophysiology. n/a.2. Martínez-Alday JD, Almendral J, Arenal A, et al. Identification of concealed posteroseptal Kent pathways by comparison of ventriculoatrial intervals from apical and posterobasal right ventricular sites. Circulation. 1994;89:1060–1067.3. Derval N, Skanes AC, Gula LJ, et al. Differential sequential septal pacing: A simple maneuver to differentiate nodal versus extranodal ventriculoatrial conduction. Heart Rhythm. 2013;10:1785–1791.FIGURE 1 - Diagram illustrating the concept of differential pacing/entrainment using the “Line of Block” principle.

Objective: The potential risk of inducing ventricular arrhythmias was explored by employing Pulsed Field Ablation (PFA) through the administration of both monophasic and biphasic waveform deliveries. Methods: Pulsed Field Ablation (PFA) was applied to specific locations in the right ventricle (RV, n=5 sites) in swine (n=2), utilizing identical settings with consistent amplitude, pulse width, and number of pulses for both monophasic and biphasic waveforms. PFA deliveries were precisely timed in 10-milisecond intervals across the entire T wave. Results: Using monophasic waveforms, ventricular fibrillation (VF) was induced 7/7 times when PFA pulses were delivered during the T wave. Biphasic waveforms resulted in no ventricular arrhythmias when PFA was delivered across the entire duration of T wave. Conclusions: Our findings indicate that VF can be consistently induced with monophasic pulse waves, but not with biphasic pulse waves in a porcine model.

Background: Left bundle branch area pacing (LBBAP) and endocardial resynchronization (Endo-CRT) are alternatives to biventricular pacing for cardiac resynchronization therapy (CRT). Objective: To compare the outcomes of LBBAP vs. Endo-CRT using conventional pacing leads. Methods: Patients with heart failure (HF) undergoing CRT with LBBAP or Endo-CRT were included. The primary efficacy outcome was a composite of HF-related hospitalization and all-cause mortality. The primary safety outcome was any procedure-related complication. Secondary outcomes included procedural characteristics, electrocardiographic, and echocardiographic parameters. Results: A total of 223 patients (LBBAP n=197, Endo-CRT n=26; mean age 69±10.3 years, 32.3% female) were included. Patients in the LBBAP group had lower NYHA class, shorter preprocedural QRS durations (161 [142-183] vs. 180 [170-203] msec, p<0.001), and a lower preprocedural spironolactone use (57.4% vs. 84.6%, p=0.009) than patients in the Endo-CRT group. Fluoroscopy time was significantly shorter in patients undergoing LBBAP (11.4 [7.2-20] vs. 23 [14.2-34.5] min; p<0.001). There was no significant difference in the primary efficacy outcome between both groups (Cox proportional HR 1.21, 95% CI 0.635-2.31; p=0.56). During follow-up, patients undergoing LBBAP had a lower incidence of stroke than patients in the Endo-CRT group (0% vs. 11.5%, p=0.001). Postprocedural LVEF (35% [25-45] vs. 40% [20-55]; p=0.307) and change in LVEF (7% [0-20] vs. 11% [2-18]; p=0.384) between the LBBAP and the Endo-CRT groups, respectively. Conclusion: LBBAP and Endo-CRT using conventional leads are associated with similar clinical outcomes, as well as improvements in LVEF. Endo-CRT is associated with longer fluoroscopy times and a higher risk of stroke.

Background Data are scarce regarding WPW syndrome and asymptomatic pre-excitation in Africa. Objectives This study aimed to understand how accessory pathways related arrhythmias are managed in Africa. Methods This prospective study was conducted in 20 centers from 17 African countries. All the included participants had ventricular pre-excitation patterns. The data collected included symptoms, locations of accessory pathways (AP) and tachyarrhythmia, risk stratification, as well as acute and long-term management. In addition, we assessed the clinical effectiveness and the impact of socio-economic and health metrics on this treatment approach. Results Of 541 participants, 93% were diagnosed with WPW syndrome, and orthodromic atrioventricular reciprocating tachycardia (AVRT) was the most prevalent arrhythmia, affecting 55% of the cases. Approximately 30% of patients, excluding the southern region, received Intravenous Amiodarone as the first-choice drug for orthodromic AVRT while Adenosine was the drug of choice in Southern region. Electrical cardioversion was the first-line treatment for pre-excited atrial fibrillation and antidromic AVRT across all of Africa. Radiofrequency ablation was the first long-term therapy option for 88 % of patients in all African regions, except in western and central Africa, where it was implemented for less than 30% of patients (P<0.001). The rates of success, long-term recurrence, and complication were 93%, 4.1%, and 3.8%, respectively. Conclusion Significant differences and challenges in the diagnosis and management strategies among countries are reported across Africa. While several countries fell short of ideal or expected health expenditures, ablation techniques are rising with success rates comparable to those in the developed world.

A document by Amneet Sandhu. Click on the document to view its contents.

Editorial to: Efficacy and safety of a novel temperature-controlled catheter for cavotricuspid isthmus ablationHristijan Alagjozovski1 and Christian-H. Heeger2,3,41 Department of Cardiology and Angiologie, Helios Kliniken Schwerin, Germany2 Department of Rhythmology; Cardiology and Internal medicine, Asklepios Klinik Hamburg Altona, Hamburg, Germany.3 Department of Rhythmology, University Heart Center Lübeck, University Hospital Schleswig-Holstein, Germany.4 German Center for Cardiovascular Research, Partner Site Hamburg / Kiel / Luebeck, Luebeck, Germany.

Background Atrial fibrillation (AF) is the most common cause of arrhythmia-induced cardiomyopathy. Effective management strategies include medical therapy for rate and rhythm control, catheter ablation (CA), and goal directed medical therapy. Sodium-glucose co-transporter 2 inhibitors (SGLT2i), a novel class of anti-diabetic drugs, have shown a promising impact in reducing cardiovascular events in diabetic and non-diabetic heart failure (HF) patients. It is unclear what impact SGLT2i use may have on AF recurrence following catheter ablation. Aim To evaluate the effects of SGLT2i on preventing AF recurrence following CA and impact on other cardiovascular outcomes. Methods and results We performed a comprehensive literature search through multiple search engines (Pubmed, Scopus, Web of Science, and Cochrane) to include eligible studies using the appropriate keywords until 10th April 2024. Our search yielded nine eligible studies with 16,857 patients. Our analysis reveals a significant reduction in AF recurrence after catheter ablation among patients receiving SGLT2i compared to non-SGLT2i medications (RR = 0.72, 95% CI [0.67, 0.78], P < 0.00001). Additionally, SGLT2i therapy was associated with decreased all-cause hospitalizations and reduced risk of ischemic stroke. However, no significant difference in all-cause mortality was observed between SGLT2i and non-SGLT2i groups. Conclusion Our study found that SGLT2 inhibitors significantly reduced AF recurrence post-CA in diabetic patients. Moreover, SGLT2i use was associated with lowered hospitalization and ischemic stroke risk. Though no significant difference in mortality was noted, the decrease in hospitalization suggests a possible favorable effect on cardiovascular events.