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; [email protected] of Medicine, University of Chicago, Chicago, IL; [email protected] author: William Whang, MD ([email protected])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: [email protected]: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: Premature ventricular contractions (PVCs) are frequently observed with left ventricular (LV) systolic dysfunction, although the prevalence of these associated conditions in the general population remains unknown. Objective: We sought to understand the prevalence of frequent PVCs (defined PVCs>5%) and high burden PVCs (defined PVCs>10%) and LV systolic dysfunction in patients receiving ambulatory Holter monitors (HM). Methods: A prospective multicenter (8 US medical centers) cross-sectional study collected demographic and PVC burden data from consecutive patients undergoing 24-hour, 48-hour, and 14-day HM (July 2018-June 2020). Left ventricle ejection fraction (LVEF) data was collected if obtained within 6 months of HM. Four PVC burden groups were analyzed (<1%, 1-5%, 5.1-10% and >10% burden) and stratified by normal LVEF (≥50%) or presence LVEF<50%. Results: The prevalence of PVC burden of 5.1-10% and >10% was 4% and 5%, respectively in the population undergoing HM (n=6,529). Age was significantly different between PVC groups (p<0.001). In those with LVEF assessment (n=3,713), the prevalence of LVEF<50% and both LVEF<50% and PVC>5% was 16.4% and 4.2%, respectively. The prevalence of PVC>5% and PVC>10% in patients with LVEF<50% was 26% and 16%, respectively. PVC>5% were more prevalent in older, male, and Caucasians (p<0.001). Females had a lower prevalence of PVC>5% than males (6% vs. 11%; p<0.001), but not among those with LVEF<50% (24% vs. 26%, p=0.10). Conclusion: PVC>5% and PVC>10% and LVEF<50% are prevalent in patients undergoing HM. PVC>5% are associated with older age. Females have a lower prevalence of PVC>5% than males but similar combined PVC>5% and LVEF<50%.

COVID-19 Vaccination and Atrial fibrillation: When Pandemics CollideJason S. Chinitz, MD1,2,3 and Laurence M. Epstein, MD1,2,41Northwell, New Hyde Park, NY2Northwell Cardiovascular Institute3South Shore University Hospital, Bay Shore, NY4North Shore University Hospital, Manhasset, NYShort title : COVID-19 Vaccination and Atrial fibrillationKey Words : Atrial Fibrillation, Atrial Arrhythmias, COVID-19, COVID-19 VaccinationFinancial support : none.Conflicts of Interest :Jason Chinitz, MD: Consultant for Boston Scientific, Biosense Webster, MedtronicLaurence Epstein, MD: none.Address for Correspondence :Jason Chinitz, MDNorthwell, 2000 Marcus Ave, Suite 300New Hyde Park, NY [email protected] the wake of the coronavirus disease 2019 (COVID-19) pandemic, accelerated research and development efforts were made to create a new class of vaccinations to mitigate the unprecedented global health burden. However, the rapid development and approval process was a factor in prompting vaccine hesitancy, based partially on concerns regarding the safety of the vaccine. Adding to the hesitancy, reports of adverse reactions became widely disseminated in medical literature, as well as in social media. However, the lack of long-term data and controlled studies have limited interpretation of the true COVID-19 vaccine risk profile, and has hampered the effort to combat misinformation.Cardiac complications are the most frequently reported adverse reaction following COVID-19 vaccination.1 Case series have attributed exacerbations of various chronic cardiac diseases to COVID-19 vaccination, including hypertension, coronary artery disease, and arrhythmias.2 In the WHO database, palpitation and tachycardia were reported frequently across all age groups and gender following vaccination, including many cases of atrial fibrillation.2 The Vaccine Adverse Event Report System (VAERS) database of the Food and Drug Administration reported over 2600 cases of atrial fibrillation following COVID-19 vaccination, only 315 of which were reported as new-onset.3 These reports, however, are generally anecdotal, denominators are not considered, and causality cannot be inferred. Any association is further confounded when evaluating the vaccine’s effects in populations in whom cardiovascular disease is the most common comorbidity, as the prevalence of heart rhythm abnormalities is already high. In this circumstance, patients and clinicians may tend to inappropriately attribute an arrhythmia occurrence to a history of vaccination. Indeed, the majority of adverse medical outcomes that occur following vaccination may have little to do with the vaccine itself, even when the temporal relationship is suggestive.Tachycardia and arrhythmias may occur as an inflammatory or stress-related response to vaccination. Inflammatory reactions such as myocarditis and pericarditis have been shown to occur at higher rates following COVID-19 vaccination.4 A potential mechanism of post-COVID-19 vaccine adverse events has been attributed to an immune response to the detection of mRNA as an antigen, particularly in genetically predisposed individuals; in these cases, immunization may activate inflammatory cascades, leading to systemic reactions including myocarditis and potentially atrial and ventricular arrhythmias.5 Atrial fibrillation and ventricular arrhythmias have been long associated with inflammatory conditions, and are relatively common in patients with pericarditis and myocarditis.6 Accordingly, an increase in arrhythmia burden after vaccination is biologically plausible, regardless of whether the vaccine itself is pro-arrhythmic.For practicing cardiologists, atrial fibrillation can reasonably be considered a disorder of pandemic proportions. Driven by both modifiable and non-modifiable risk factors, and more ubiquitous screening and detection modalities, the incidence of AF has been reported to be 31% higher in 2017 compared to 1997, and predictive models suggest AF will impact nearly 8 million Americans by 2050.7,8Furthermore, AF burden is progressive in at least 25% of patients, including progression from paroxysmal to persistent AF in 8-15% of patients per year.9 AF interventions, particular AF ablation, have been shown to reduce the rate of progression to persistent AF markedly.10Though increasing AF burden in an individual patient may be attributed to the natural history of the disease, cardiovascular risk factors are commonly implicated as drivers of AF progression. Interestingly, the pandemic itself may have also contributed to the increasing prevalence of AF, as we have reported high rates of AF, nearly two-thirds of which was new onset, in large numbers of hospitalized patients with COVID-19.11 However, in most patients with AF who have various cardiac risk factors, identification of extrinsic factors such as a novel vaccination that may contribute directly to AF onset and progression is challenging, and non-randomized studies can be misleading due to unrecognized confounders.In the study reported in this issue of the Journal of Cardiovascular Electrophysiology by Deshmukh et al,12arrhythmia burden was extracted retrospectively in large databases of patients with CIEDs, to evaluate any temporal association between COVID-19 vaccination and AF progression. Insurance claims were used to identify patients receiving COVID-19 vaccination, and long-term trends in arrhythmia burden, occurring before and after vaccination were analyzed, and compared to similar populations not undergoing vaccination. Though the AF burden was found to increase in the 3 months following vaccination, similar increases in AF burden were observed in patients who did not receive vaccination over the same time frame, and sustained increases in arrhythmia burden were noted over the course of a year, in both populations. These findings implicate disease progression, and not the vaccine itself, as the primary driver of AF events occurring following vaccination. This manuscript’s first conclusion citing an increase in the burden of arrhythmia events in the 3 months following COVID-19 vaccination, particularly in males over 70 years in whom the prevalence of AF is already highest, is therefore potentially misleading, as a subsequently reported comparison between matched vaccinated and un-vaccinated populations yielded no statistically significant difference in AF burden.There are two primary lessons to take from this research.AF is a common and progressive disease, which is best understood in populations that have devices capable of long-term arrhythmia monitoring. Beyond observed and predicted increases in AF prevalence and incidence over time, AF burden in individual patients is progressive over time. This study further demonstrates this trend in a population with underlying cardiovascular disease who have CIEDs, regardless of whether they had a vaccination or not.Exacerbations of chronic medical disease, such as atrial fibrillation, are seen following vaccinations, and may be in-part related to the vaccine\RL’s induced inflammatory response. However, in this study, arrhythmia burden did not appear to accelerate more quickly in patients who received vaccinations relative to those who did not get vaccinated, and no long-term difference in atrial or ventricular arrhythmia burdens were noted between these populations.A risk versus benefit analysis must always be performed when evaluating any therapy, including with vaccines. While this study does not report on the benefits of the vaccine, it does provide some reassurance in recommending COVID-19 vaccination to our patients at risk for arrhythmias, who are also at high risk of complications from COVID-19 infection. Furthermore, the progressive nature of AF in patients with cardiovascular disease, who are at highest risk of AF-related morbidity and mortality, further justifies current trends towards early AF intervention.

Title: Oh Groin: What to do with thou?Author: Gautam [email protected] of Missouri School of Medicine, Division of Cardiovascular MedicineThe field (art?) of electrophysiology (EP) has progressed exponentially over the last 3 decades. The delivery of ablative energy through transvenous catheters has revolutionized our ability to treat cardiac arrhythmia. At the time that this text is being put on paper, there are 3 remaining challenges in our field, namely, durable ablation for atrial fibrillation, ablation of non-focal non-ischemic ventricular tachycardia, and last but not the least, management of the pesky inguinal access region. The oral history of electrophysiology trainees is riddled with the litany of post-operative complaints from both patients and nurses, prolonged repeated compressions and late-night vascular imaging. Those of our ilk who have been unfortunate enough to deal with pseudoaneurysms and arteriovenous fistulae can never forget the resultant prolonged patient agony and depression. Thankfully, these have decreased significantly with the advent of ultrasound-guided vascular access.The ideal modality of post-ablation venous hemostasis should have each of the following characteristics: simple, fast, 100% effective, allow rapid patient mobility, and above all, cheap. This combination, however, has been surprisingly elusive. As opposed to the multitude of arterial closure options for our interventional colleagues, the electrophysiology field for long relied upon the old and non-tested method of plain manual compression (MC). As most of us have experienced, MC is unreliable and messy especially in procedures on uninterrupted anticoagulation. The degree and efficiency of MC is almost completely operator dependent. Luckily, the femoral veins are easily compressible and usually quite forgiving in the majority of cases. However, as we started to recognize the advantage of both uninterrupted anticoagulation and deep sedation (preferably general anesthesia) in left atrial ablation procedures, particularly atrial fibrillation (AF), MC became even more unreliable in ensuring venous haemostasis.The Figure-of-Eight (Fo8) suture was a handy replacement for MC. The goal of Fo8 is simple: create a compression zone of subcutaneous fat to allow healing of the venous puncture track. Fo8 seems to work well for all venous access procedures, allowing haemostasis even for large venous sheaths such as cryoablation, left atrial appendage closure systems and leadless pacemaker delivery sheaths. The Fo8 was a particular godsend for electrophysiologists without the luxury of MC by willing trainees or reliable lab staff. We and others also showed that it resulted in shorter lab recovery time after AF ablation and was reliable in presence of systemic anticoagulation. However, there remained a few drawbacks. The ideal duration of suture compression remains unknown and is variable by practice, from 2 to 4 hours, sometimes longer for larger or multiple sheaths. The degree of venous compression is lesser compared with MC, as evidenced by persistent oozing in some patients after Fo8 removal necessitating prolonged compression or administration of subcutaneous Lidocaine with Epinephrine. The requirement for ‘suture cutting’ also meant that nursing staff were uncomfortable removing it. The last and greatest drawback was that Fo8 is irreversible, that is, the suture could not be reapplied when cut, for patients with persistent oozing.The above drawbacks led to the development of the stopcock (SC) technique. This was being used by some vascular surgeons, called the ‘Woggle technique’ for suture closure of hemodialysis access catheterization sites (1). Sam Aznaurov first described this technique on ‘X’ (then Twitter) for femoral venous haemostasis (2). I and others tried it on a few patients and were impressed by the ease and sophistication of the technique. We published the first detailed description of this technique in 2018 showing it to be equivalent to Fo8 in achieving access site haemostasis in AF ablation patients (3). The SC technique, which is essentially using a simple 3-way stopcock to lock a tightened 0-Ethibond or 0-silk suture, has 2 major advantages over Fo8. It is easier to teach and apply, can be removed by nursing personnel and can be reapplied (the stopcock can simply be locked again) if haemostasis is incomplete. The technique is also inexpensive, as the stopcocks can simply be cut from the side arm of the venous sheaths. We also further showed that Heparin reversal with Protamine was not required for haemostasis with SC.As expected, Fo8 and SC have been widely taken up in EP labs around the world. In other centers, MC remains king. Many centers in the US have graduated to specialized venous closure devices which afford faster ambulation but are considerably more expensive. The time is ripe for the SC system to be commercialized and a few of these are being tested now in the EP community.In the present use of JCE, Katapadi and colleagues present a single-center retrospective observational analysis of 102 patient who underwent venous hemostasis with the LockeT vascular compression device (4). They report complete hemostasis in 97.8% of vascular access without major complications, mean time to ambulation 3.93 ± 1.10 hrs. The LockeT device is a commercial apparatus which uses a screw with 90 degrees rotation to lock or unlock the suture, with a flat round endplate (base) to provide uniform compression. Theoretically, the flat base would avoid one prior complaint with SC, namely skin pressure/ ulceration. Truly speaking, operators have long developed methods to avoid skin ulceration, including shorter SC retention times, use of an intervening gauze roll, and gentler compression in non-obese individuals. In this relatively small study, the authors have shown 98% complete hemostasis (likely prolonged compression in 2 patients), a stable mean ambulation time of 4 hours and mean time to discharge 8 hours (which could potentially be shortened with increased operator experience). The study has the usual drawbacks of retrospective observational studies, as acknowledged by the authors, as well as the lack of any comparative analysis to SC technique. We also do not have information about the financial implications of adding to the technical costs of EP studies or appendage closure. In the current reimbursement climate, especially with steadily rising healthcare costs, this would be important information.The LockeT device and other similar commercial devices that duplicate SC would be potentially useful if a) they add negligible incremental cost to the EP procedure and b) if they lead to further shortening of bedrest and time to discharge which would offset the device expenditure. One might argue against their use for simple EP procedures without systemic anticoagulation where MC has historically been simple and effective. These methods would be expected to hold an advantage over invasive venous closure devices of not requiring multiple devices (one for each access site), thus being less expensive, especially if the patient could be discharged within 2 hours as practiced by some operators with the venous closure devices. We need more larger volume studies on these issues to convince the greater the EP community.We could thus be finally reaching closer to a solution of the waxing problem: what to do with the groin?References:Simons ME, Rajan DK, Clark TW. The Woggle technique for suture closure of hemodialysis access catheterization sites. Journal of vascular and interventional radiology: JVIR 2003;14:485-8.https://x.com/epTicTocDoc/status/917473407524134914Payne J, Aznaurov S, Gautam S. Three-way stopcock suture technique for hemostasis after ablation for atrial fibrillation. J Cardiovasc Electrophysiol. 2018;29(12):1724-1727.(Attach reference for the LockeT manuscript )

not-yet-known not-yet-known not-yet-known unknown The decremental properties of the nodoventricular pathway (NVP) are uncertain. During short RP supraventricular tachycardia, a His-refractory premature ventricular contraction (PVC) consistently terminated the tachycardia without atrial capture immediately after the PVC. Whereas a slightly earlier PVC failed to reset the subsequent His but terminated the tachycardia without atrial capture one cycle later. These observations are diagnostic of slow-fast atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed-NVP and can be explained by decremental properties in the NVP itself; greater prematurity of the PVC resulted in more decremental conduction over the NVP, causing the AVNRT termination one cycle later.