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.

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.

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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.

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.

Abtract not needed for a response to a Letter to the Editor

Atypical Atrial Flutter Ablation: The Clinical Impact of High-Density MappingBahjat Z. Ghazzal MD1, Marwan M. Refaat, MD21 Division of Cardiology, Department of Internal Medicine, University of Massachusetts Chan Medical School , Worcester, Massachusetts, USA2 Division of Cardiology, Department of Internal Medicine, American University of Beirut Medical Center, Beirut, LebanonRunning Title: Atypical Atrial Flutter Ablation: The Clinical Impact of High-Density MappingWords: 700 (excluding the title page and references)Keywords: cardiac arrhythmias, heart diseases, cardiovascular diseases, catheter ablation, atrial flutter, high density mappingFunding: 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 Program American 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)Atypical atrial flutter (AAFL) is an arrhythmia that is distinct from typical atrial flutter (AFL) due to its non-isthmus-dependent reentrant circuit, and often arises in patients with a history of cardiac surgery or ablation, where the resulting iatrogenic scar provides the basis for re-entry circuits.1 Catheter ablation for AAFL is an effective treatment option, associated with lower rates of thromboembolic events, transfusions, and shorter hospital stays compared to typical AFL.2 However, the complexity of AAFL circuits requires precise mapping, and traditional techniques often lack the resolution to accurately delineate these pathways. High-density (HD) mapping technology has emerged as a significant advancement in this regard, offering detailed electroanatomic maps that enhance procedural success.3 In this issue of the Journal of Cardiovascular Electrophysiology, the study by Sink et al. investigates the impact of HD mapping on AAFL ablation outcomes and healthcare utilization, providing valuable insights into its clinical benefits.4In this retrospective analysis, Sink et al. examined 108 patients who underwent AAFL ablation at a single academic center from 2005 to 2022. The cohort was divided into two groups: those who received HD mapping with a 16-electrode HD Grid catheter and Precision mapping system, and those who underwent non-HD mapping using traditional spiral catheters and the Velocity system. Primary outcomes included procedural success, defined as non-inducibility of the arrhythmia after ablation, and AFL recurrence. Secondary outcomes included emergency department (ED) visits, hospitalizations, and overall healthcare utilization within one-year post-procedure. The study revealed that HD mapping significantly improved both the delineation of AAFL circuits (92.5% vs. 76%; p=0.014) and procedural success rates (91% vs. 71%; p=0.006). Additionally, patients in the HD mapping group experienced significantly fewer ED visits (aIRR 0.32; p=0.007) and hospitalizations (aIRR 0.32; p=0.004) for AF/AFL/HF within the first year. While there was a trend towards lower AFL recurrence in the HD mapping group (aHR 0.60; p=0.13), this difference did not reach statistical significance. This study highlights the significant advantages of HD mapping in AAFL ablation. The enhanced resolution provided by HD mapping allows for more precise identification and targeting of arrhythmogenic substrates, leading to improved clinical outcomes.Though this study was well-conducted, minor limitations must be noted. The study’s retrospective design and single-center setting introduce potential biases and limit the generalizability of the results. The non-randomized nature of the study also raises the possibility of selection bias. Furthermore, the higher use of contact force-sensing catheters in the HD mapping group may have contributed to the observed differences in outcomes. A larger sample size would have likely allowed the study to achieve statistical significance when comparing recurrent AAFL rates between groups. Despite these limitations however, this study provides strong support for the clinical utility of HD mapping in AAFL ablation. Future multi-center, randomized trials should validate these findings and examine factors not studied here, such as procedure fluoroscopy time and complication rates between groups. Long-term benefits should also be further investigated, as some prior studies for example have shown no significant decrease in anti-arrhythmic drug use at 1-year follow-up5 and significantly decreased rates of sinus rhythm maintenance for repeat ablations compared with single ablations6. Research on HD mapping in patients with specific comorbidities could also provide insights into its broader applicability. For instance, one study showed a greater chance of acute procedural failure in patients with a history of surgical correction for congenital heart disease.7 Though HD-mapping-guided ablation demonstrates higher acute procedural success, several studies have shown long-term recurrence rates remain significant.8, 9 Hence, further research is needed to identify strategies to reduce these rates. In this context, the development of new mapping tools, such as the Octaray TM system (Biosense Webster Inc., Irvine, CA, USA)10 and the Ensite TM Omnipolar Technology (OT) (Abbott, Chicago, IL, USA)11, may offer improved outcomes. Further research is also needed to assess the clinical outcomes, healthcare utilization and biomarker response for ablation of AAFL with HD mapping in the setting of heart failure with reduced ejection fraction.12 To the best of our knowledge, this is the first such study to demonstrate that ablation with HD mapping for AAFL results in reduced re-hospitalization and ED visits. Future research should attempt to expand on these findings to evaluate potential cost-benefit and impact on patient quality of life.References:1. Cherian Tharian S, Supple G, Smietana J, Santangeli P, Nazarian S, Lin D, Hyman Matthew C, Walsh K, Marchlinski F and Arkles J. Idiopathic Atypical Atrial Flutter Is Associated With a Distinct Atriopathy.JACC: Clinical Electrophysiology . 2021;7:1193-1195.2. Ko Ko NL, Sriramoju A, Khetarpal BK and Srivathsan K. Atypical atrial flutter: review of mechanisms, advances in mapping and ablation outcomes.Curr Opin Cardiol . 2022;37:36-45.3. Raymond-Paquin A, Pillai A, Myadam R, Mankad P, Lovejoy S, Koneru JN and Ellenbogen KA. Atypical atrial flutter catheter ablation in the era of high-density mapping.J Interv Card Electrophysiol . 2023;66:1807-1815.4. Sink JC, Kasen; Uppalapati, Lakshmi; Lancki, Nicola; Peigh, Graham; Lohrmann, Graham; Elsayed, Mahmoud; Carneiro, Herman; Baman, Jayson; Pfenniger, Anna; Patil, Kaustubha D.; Verma, Nishant; Arora, Rishi; Kim, Susan S.; Chicos, Alexandru B.; Lin, Albert C.; Knight, Bradley P.; Passman, Rod S. Association Between High-Density Mapping of Atypical Atrial Flutter, Clinical Outcomes and Healthcare Utilization. Journal of Cardiovascular Electrophysiology . 2024.5. Balt JC, Klaver MN, Mahmoodi BK, van Dijk VF, Wijffels MCEF and Boersma LVA. High-density versus low-density mapping in ablation of atypical atrial flutter.Journal of Interventional Cardiac Electrophysiology . 2021;62:587-599.6. Marazzato J, Cappabianca G, Angeli F, Crippa M, Golino M, Ferrarese S, Beghi C and De Ponti R. Catheter ablation of atrial tachycardias after mitral valve surgery: a systematic review and meta‐analysis. Journal of Cardiovascular Electrophysiology . 2020;31:2632-2641.7. Delacretaz E, Ganz Leonard I, Soejima K, Friedman Peter L, Walsh Edward P, Triedman John K, Sloss Laurence J, Landzberg Michael J and Stevenson William G. Multiple atrial macro–re-entry circuits in adults with repaired congenital heart disease: entrainment mapping combined with three-dimensional electroanatomic mapping.Journal of the American College of Cardiology . 2001;37:1665-1676.8. Lozano-Granero C, Moreno J, Sanchez-Perez I, Matia-Frances R, Hernandez-Madrid A, Zamorano JL and Franco E. Results of atypical flutter ablation in the era of high density electroanatomical mapping (the RAFAELA study). European Heart Journal . 2023;44.9. Anter E, McElderry TH, Contreras-Valdes FM, Li J, Tung P, Leshem E, Haffajee CI, Nakagawa H and Josephson ME. Evaluation of a novel high-resolution mapping technology for ablation of recurrent scar-related atrial tachycardias. Heart Rhythm . 2016;13:2048-2055.10. Sroubek J, Rottmann M, Barkagan M, Leshem E, Shapira‐Daniels A, Brem E, Fuentes‐Ortega C, Malinaric J, Basu S and Bar‐Tal M. A novel octaray multielectrode catheter for high‐resolution atrial mapping: electrogram characterization and utility for mapping ablation gaps. Journal of Cardiovascular Electrophysiology . 2019;30:749-757.11. Rillo M, Palamà Z, Punzi R, Vitanza S, Aloisio A, Polini S, Tucci A, Pollastrelli A, Zonno F, Anastasia A, Giannattasio CF and My L. A new interpretation of nonpulmonary vein substrates of the left atrium in patients with atrial fibrillation. Journal of Arrhythmia . 2021;37:338-347.12. Pascual-Figal D, Wachter R, Senni M, Bao W, Noè A, Schwende H, Butylin D, Prescott MF; TRANSITION Investigators. NT-proBNP Response to Sacubitril/Valsartan in Hospitalized Heart Failure Patients With Reduced Ejection Fraction: TRANSITION Study. JACC Heart Fail Oct 2020;8(10):822-833.

not-yet-known not-yet-known not-yet-known unknown The Efficiency of using KardiaMobile 6L in the Cardiac Electrophysiology Clinic Bahjat Z. Ghazzal MD1, Marwan M. Refaat, MD2 1 Division of Cardiology, Department of Internal Medicine, University of Massachusetts Chan Medical School , Worcester, Massachusetts, USA 2 Division of Cardiology, Department of Internal Medicine, American University of Beirut Medical Center, Beirut, Lebanon Running Title: The Efficiency of KardiaMobile 6L in Clinic Words: 719 (excluding the title page and references) Keywords: Electrocardiogram, cardiac arrhythmias, cardiology, cardiovascular diseases, Utilization Time, Efficiency Funding: None Disclosures: None Corresponding Author: Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FRCP Tenured Professor of Medicine Tenured Professor of Biochemistry and Molecular Genetics Member, Division of Cardiology/ Section of Cardiac Electrophysiology Director, Cardiovascular Fellowship ProgramAmerican University of Beirut Faculty of Medicine and Medical Center PO Box 11-0236, Riad El-Solh 1107 2020- Beirut, Lebanon US Address: 3 Dag Hammarskjold Plaza, 8th Floor, New York, NY 10017, USA Office: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct) Electrocardiography (ECG) is an essential diagnostic tool in cardiology, allowing for the detection and management of various cardiac conditions. Traditional 12-lead ECGs, while comprehensive, can be time-consuming and may impact clinic efficiency. This may be particularly important in outpatient cardiology clinics, where time can often be a scarce resource. A survey distributed at the 2022 ESC congress found that while most cardiologists believe that consultations should last 30 to 45 minutes, they often have only 20 minutes or less.1 Although the effects of time pressure have not been extensively studied in cardiology and cardiac electrophysiology outpatient clinics, research in primary care has linked it to increased physician stress, burnout, intent to leave the practice2 in addition to lower diagnosis rates and higher follow-up care rates3. Research has also shown that increasing system efficiency and improving patient cycle time in primary care clinics can improve patient experience and access as well as staff satisfaction.4 Thus, the introduction of KardiaMobile 6-lead ECG (Figure 1), a more portable and user-friendly device, could present an opportunity to streamline ECG collection and potentially improve clinic time utilization. The study by Gaddam et al. explores this potential by comparing room utilization times between KardiaMobile 6-lead ECG and the standard 12-lead ECG in a cardiology clinic setting. In their study, Gaddam et al. conducted a single-center, non-randomized trial involving 100 patients aged 18 to 89, excluding those with resting tremor. The participants were divided into two groups: one underwent ECG collection using KardiaMobile 6-lead ECG, and the other using the traditional 12-lead ECG. The primary outcome measured was room utilization time, with secondary outcomes including the need for additional 12-lead ECGs. The results demonstrated a significant reduction in room utilization time with KardiaMobile 6-lead ECG (7.27 minutes) compared to the 12-lead ECG (10.33 minutes, p < 0.001). Only 16% of visits in the KardiaMobile 6-lead ECG group required an additional 12-lead ECG, indicating that KardiaMobile 6-lead ECG is sufficient for most clinical needs. The primary benefit of 6-lead ECGs lies in their portability and ease of use, making them suitable for continuous monitoring and rapid assessment in both clinical and non-clinical settings. Although research on this subject is still limited, a recent prospective study of 1,015 participants found that the KardiaMobile 6-lead ECG demonstrates a high level of agreement with 12-lead ECGs for certain parameters like PR interval, QRS duration, and cardiac axis, but may be less effective for detecting conditions that require detailed precordial lead information, such as left ventricular hypertrophy or specific ischemic changes.5 Other studies have also corroborated acceptable agreement in certain ECG parameters between 6-lead and 12-lead ECG’s, however, highlighting the 12-lead ECG’s advantage in certain situations where broader and more detailed data collection is required.6,7 While this study was well-conducted, minor limitations exist. The study follows a non-randomized design, which may potentially introduce selection bias and the team members were non-blinded, which may introduce observer bias. Additionally, the relatively small sample size and single-center nature of the study may limit generalizability. It must also be noted that nearly half of the patients in each group (KardiaMobile 6-lead ECG vs. 12-lead ECG) visited the clinic for atrial fibrillation and/or atrial flutter follow-up, conditions that can be detected with just a 1-lead ECG. Finally, while the study shows a statistically significant reduction in average room utilization time by 3.07 minutes, it does not assess whether this reduction translated to meaningful improvements in tangible clinic efficiency outcomes. Despite these limitations, the study provides valuable insights into the potential benefits of integrating KardiaMobile 6-lead ECG into clinical practice. It could lead to improved clinical workflows, allowing clinicians to see more patients without compromising the quality of care. This device may also be particularly beneficial in remote or resource-limited settings where traditional 12-lead ECGs are impractical. Future research should focus on larger, randomized trials to validate these findings and explore the long-term benefits and potential limitations of KardiaMobile 6-lead ECG in diverse clinical environments. Furthermore, investigating the use of KardiaMobile 6-lead ECG in specific patient populations, such as those with complex arrhythmias or comorbidities associated with arrhythmias such as cardiomyopathies and heart failure, could provide additional insights into its clinical utility.8,9 The development of guidelines and protocols for integrating KardiaMobile 6-lead ECG into routine practice will be essential to maximize its benefits and ensure patient safety. Legend Figure 1: Kardia 6L Electrocardiogram (Mountain View, CA) References: https://doi.org/10.1016/j.jelectrocard.2021.03.008 1. Sala O, Moscatelli S. Time matters. Global assessment of quality, duration and mismatch between real practice working conditions and physician needs performing outpatients cardiological consultations. European Heart Journal . 2022;43. doi: 10.1093/eurheartj/ehac544.28352. Prasad K, Poplau S, Brown R, Yale S, Grossman E, Varkey AB, Williams E, Neprash H, Linzer M, for the Healthy Work Place I. Time Pressure During Primary Care Office Visits: a Prospective Evaluation of Data from the Healthy Work Place Study. Journal of General Internal Medicine . 2020;35:465-472. doi: 10.1007/s11606-019-05343-63. Freedman S, Golberstein E, Huang TY, Satin DJ, Smith LB. Docs with their eyes on the clock? The effect of time pressures on primary care productivity. J Health Econ . 2021;77:102442. doi: 10.1016/j.jhealeco.2021.1024424. Robinson J, Porter M, Montalvo Y, Peden CJ. Losing the wait: improving patient cycle time in primary care. BMJ Open Quality . 2020;9:e000910. doi: 10.1136/bmjoq-2019-0009105. Azram M, Ahmed N, Leese L, Brigham M, Bowes R, Wheatcroft SB, Ngantcha M, Stegemann B, Crowther G, Tayebjee MH. Clinical validation and evaluation of a novel six-lead handheld electrocardiogram recorder compared to the 12-lead electrocardiogram in unselected cardiology patients (EVALECG Cardio). European Heart Journal - Digital Health . 2021;2:643-648. doi: 10.1093/ehjdh/ztab0836. Madias JE. A Comparison of 2-Lead, 6-Lead, and 12-Lead ECGs in Patients With Changing Edematous States: Implications for the Employment of Quantitative Electrocardiography in Research and Clinical Applications. CHEST . 2003;124:2057-2063. doi: 10.1378/chest.124.6.20577. Orchard JJ, Orchard JW, Raju H, La Gerche A, Puranik R, Semsarian C. Comparison between a 6‑lead smartphone ECG and 12‑lead ECG in athletes. Journal of Electrocardiology . 2021;66:95-97. doi: 8. El Moheb M, Nicolas J, Khamis AM, Iskandarani G, Akl EA, Refaat M. Implantable Cardiac Defibrillators for patients with non-ischaemic cardiomyopathy. Cochrane Database Syst Rev Dec 2018; 12: CD012738 9. Pascual-Figal D, Wachter R, Senni M, Bao W, Noè A, Schwende H, Butylin D, Prescott MF; TRANSITION Investigators. NT-proBNP Response to Sacubitril/Valsartan in Hospitalized Heart Failure Patients With Reduced Ejection Fraction: TRANSITION Study. JACC Heart Fail. Aug 2020; S2213-1779(20)30336-X.

To the Editor of the Journal of Cardiovascular Electrophysiology, We read with great interest the article the recent publication titled ”Impact of Artificial Intelligence Arrhythmia Mapping on Time to First Ablation, Procedure Duration, and Fluoroscopy Use” by Fox et al [1]. The study investigates the effectiveness of AI-driven arrhythmia mapping in reducing time to first ablation, procedure duration, and fluoroscopy use in patients undergoing cardiac ablation. The authors conducted a retrospective analysis of 28 patients treated with traditional methods and compared the outcomes with those of 28 patients treated using the new AI mapping technology. They observed significant improvements in procedural efficiency and safety with the AI approach. While the results presented are promising, several aspects of the study deserve careful consideration to understand its full impact and limitations. First, the retrospective design of this study introduces potential biases, such as selection bias and information bias.Patients were not randomized, which could lead to differences between the control and experimental groups that are not related to the intervention. RCTs are needed to validate these findings and minimize these biases. Second, the study relies on historical controls, comparing patients treated with traditional methods in the past to those treated with AI mapping more recently. These temporal differences could introduce confounding variables, making it unclear whether the improvements are due to the AI mapping or other advancements in the field. Furthermore, the study does not provide detailed information on the specific AI algorithms used for arrhythmia mapping.Understanding the underlying technology is crucial for assessing the broader applicability of the results. Different AI models may have varying levels of effectiveness, and their performance can be influenced by the quality and type of data used for training and validation [2]. Finally, the study’s findings may not be generalizable to all clinical settings. The patient population, procedural techniques, and operator expertise at the study site may differ from those at other institutions. Further studies involving multiple centers and diverse patient populations are needed to confirm the broad applicability of the results. While the study by Fox et al. provides promising evidence of the benefits of AI in arrhythmia mapping, critical evaluation of the study design and methodology reveals several limitations that need to be addressed. Further prospective,randomized controlled trials are essential to validate these findings and ensure the robustness and generalizability of AI applications in clinical practice. This study represents an important step towards integrating AI into routine clinical practice, with the potential for significant improvements in patient outcomes and procedural efficiency. Sincerely, Federico Guerini References 1. Fox SR, Toomu A, Gu K, Kang J, Sung K, Han FT, Hoffmayer KS, Hsu JC, Raissi F, Feld GK, McCulloch AD, Ho G, Krummen DE. Impact of artificial intelligence arrhythmia mapping on time to first ablation, procedure duration,and fluoroscopy use. J Cardiovasc Electrophysiol. 2024 May;35(5):916-928. doi: 10.1111/jce.16237. Epub 2024 Mar 4. PMID: 38439119. 2. Loeffler SE, Trayanova N. Primer on Machine Learning in Electrophysiology. Arrhythm Electrophysiol Rev. 2023 Mar 28;12:e06. doi: 10.15420/aer.2022.43. PMID: 37427298; PMCID: PMC10323871.

Case Presentation: A 50-year male was referred for consideration of a redo ablation procedure. 2 years before this referral, he was diagnosed with an episode of pre-excited atrial fibrillation, and underwent an attempt at a left lateral pathway ablation. The index attempt with radiofrequency ablation did not eliminate the pathway and he was discharged on oral flecainide. The procedure was also complicated by a right-sided deep vein thrombosis and further attempts at a redo procedure were delayed. However, he developed recurrent episodes of palpitations 2 years after his index procedure. Hence, he was referred for a second attempt at ablation. His baseline 12-lead ECG did not show any evidence of manifest pre-excitation. During his EP study, pre-excitation was seen with atrial extrastimuli and with shorter intervals, a narrow complex tachycardia was induced (Figure [1](#fig-cap-0001)). However, the atrial activation appeared to alternate at times, despite the tachycardia being sustained. What is the mechanism of the alternating atrial activation?

In this review of "P-wave alternans rebound following pulmonary vein isolation predicts atrial arrhythmia recurrence," we examine a study performed by Nearing et al in the use of P-wave morphology, as a predictor of A-Fib recurrence. Patients who underwent pulmonary vein isolation, had pre and post-procedural ecgs performed specifically to monitor P-waves. With the help of artificial intelligence, objective and reproducible findings established the presence of P-wave alternans. This novel technique uses our most ubiquitous test in medicine, as a means to help hone our ability to stratify patient's risk for recurrence of their arrhythmia. And, hopefully, give clinicians a means to individualize the approach to monitor and offer prophylactic treatment to ablation patients, garnering a success level once thought unachievable.

Introduction: Catheter-based radiofrequency (RF) ablation is generally regarded as the standard approach for patients with ventricular tachycardia (VT) refractory to antiarrhythmic drug therapy and may be considered as a first line approach when there is a preference to avoid these agents. Patients with a history of cardiac surgery may have VT substrate inaccessible to catheter ablation due to intervening prosthetic materials or scar. Methods and results: This article describes a 55-year-old patient with history of surgically repaired subvalvular aortic stenosis and subsequent valve-sparing root replacement who presented with sustained VT. After RF ablation failed due to VT substrate “guarded” by graft material, retrograde coronary venous ethanol ablation (RCVEA) was employed to successfully treat the clinical VT. Conclusion: RCVEA ablation can be useful for treating VT when conventional ablation is limited by inaccessible substrate due to prior cardiac surgery.

While advances in catheter design and power delivery combined with increased awareness among operators have given more tools to avoid collateral damage, the results obtained in the accompanied manuscript are a warning that 50W and 90W 4sec LA lesions guided by 400 AI and 5 LSI using TactiCath, STSF, and QDOT MICRO do not provide immunity from significant extracardiac injury.

Background/Purpose Implantable loop recorders (ILR) are increasingly used in cardiac rhythm monitoring and diagnostic work-up of unexplained syncope. ILR battery longevity according to manufacturers’ product performance specifications typically ranges between two to four years, but real-world data in this population are lacking. Methods This monocentric, prospective, observational study included consecutive patients with unexplained syncope undergoing ILR implantation between 10/2007 and 10/2019 The main purpose was to determine real-world battery longevity of ILR. Diagnostic yield and relationship between arrhythmogenic diagnosis and duration of ILR-monitoring was explored. Results The study included 309 patients (59 years [38-73], 49% female) with ILR implantation for unexplained syncope. Median battery longevity was 42 [40-45] months. 99.5% of ILR reached prespecified battery longevity. The time to end-of-life varied by up to 33 months among the same ILR models. Overall arrhythmogenic diagnostic yield counted 27% (73% sick sinus syndrome, 20% atrioventricular block and 7% ventricular tachycardia). Median time to diagnosis was 10 [2-25] months, with the latest event at 43 months. The cumulative diagnostic yield for arrhythmogenic event was 15.7%, 22.9%, 34.9% , 54.2%, 72.3% and 100% at 1, 2, 6, 12, 24 and 48 months respectively. In univariate analysis, 1 st degree AV-block and prolonged HV time on EP study were predictors of diagnosis, while QRS duration abnormality borderline missed significance. Conclusions Real-world battery longevity of ILRs matched industry projected longevity in 99.5% of patients implanted with ILR for unexplained syncope. A battery longevity of minimum 3.5 years is recommended to maximize the diagnostic yield in this population.

Bringing big data to vascular complications during atrial fibrillation ablationDr Gareth Wynn MBChB MD(Res)[email protected]:University of Melbourne, Melbourne AustraliaThe Royal Melbourne Hospital, Melbourne AustraliaConflicts of interest:No relevant to this manuscriptAtrial fibrillation (AF) ablation has consistently been shown to be superior to medical therapy for the control of AF and relief of symptoms/ quality of life1,2. However, many patients are never considered for AF ablation and, in some cases, concerns about procedural safety may be a factor that limits access. Numerous technological advances have occurred within AF ablation over the last two decades and complication rates have steadily improved3. Although complications relating to vascular access have reduced due to the introduction of ultrasound guided cannulation as the standard of care, they remain the major contributor to the overall complication rate of AF ablation3-5. Whilst they may not always be life threatening, vascular complications can have an important effect on quality-of-life and may make same day discharge difficult, thereby reducing the efficiency and cost effectiveness of the procedure4.The use of vascular closure devices (VCDs) has become commonplace to achieve haemostasis after femoral arterial access. For AF ablation, although access is venous rather than arterial, haemostasis may still be difficult to achieve by manual compression due to the use of multiple sheaths and therapeutic heparinisation, which may be combined with uninterrupted, or very briefly interrupted, oral anticoagulation. This, along with a move, in many countries, towards same day discharge, makes the use of VCDs a potentially attractive option. However, the use of multiple VCDs in a single vein may increase the risk of venous stenosis or occlusion and thrombosis6.As overall complication rates of AF ablation have improved, with time and experience, the rates of serious complications in contemporary practice have fallen to between 2-3%3. Whilst undoubtedly a positive change, this relatively low rate can make it difficult to perform an adequately sized study with the power to detect a significant difference when trialling an intervention or approach to reduce complications. This may be one reason why recent advances such as contact force sensing catheters and pulsed field ablation have, thus far, failed to show safety benefits7.In this issue of the Journal, Mills and colleagues from Liverpool, in the UK, take a novel approach to this problem by utilising a commercial database from the United States to support the idea that vascular close your devices reduce AF ablation related complications [REF TO BE ADDED BY JOURNAL]. The TriNetX database has been used by this group, and others, to assess the association between AF ablation and outcomes such as dementia but has not been used previously to assess the impact of an intervention on ablation safety8. The study is, by its nature, observational and non-randomised and therefore is limited by the inherent uncontrollable biases of non-randomised data. In addition, the database provides anonymized patient records based on clinical coding. Databases such as this can only ever be as good as the data that has been included and neither we nor the authors are able to assess the accuracy of that process. However, the approach does allow for a very large data set with over 14000 patients in each propensity-matched group, vastly out numbering the sample size in any prospective AF ablation study. Whilst it’s possible that the absolute numbers produced by this sort of data may not be completely accurate the very large sample size does reduce the risk that occasional errors in coding had a significant effect on the overall direction of results and the differences between the two studied arms. Using this approach, and correcting for known potential confounders, the authors were able to show a significantly lower rate of vascular complications in those who those patients who had undergone AF ablation with vascular closure devices coded for during the same admission. The authors also undertook falsification endpoint analysis which, without eliminating the risk of undetected bias, add confidence that the association found was not due to chance. The results are in keeping with a number of small randomised and observational studies that have suggested vascular closure devices to be safe and effective in reducing complications and enabling early or same day discharge 9,10.It is unfortunate that the authors were not able to perform cost effectiveness analysis of the use of VCDs compared to other haemostasis strategies. AF ablation may be performed with anywhere between 1 to 5 catheters and larger access sheaths may require use more than one VCD. The associated coast of VCD use may therefore be considerable and the cost-benefit will depend on healthcare funding model and modesl of care, such as whether same day discharge is otherwise achievable and desired. This question is especially pertinent as cheaper alternatives, such as a “figure-of-eight” or ‘purse string” suture with or without a three-way stopcock, have also been shown to be superior to manual pressure alone11.That notwithstanding, the authors of this study should be commended for their innovative and novel approach, both to addressing both the important issue of complications as a primary research focus, as well as to tackling the difficulties in doing so when the overall complication rate is relatively low and therefore large cohorts are required to produce adequate statistical power. It should be noted that the study is not funded by industry and the authors were unable to provide data on closure on which closure devices were used. Whilst, to a degree, this lack of granular information could be considered a weakness of the methodology and data set, the independence of the investigators should give us some confidence in their findings and conclusion. Indeed, the authors have been appropriately reserved in their conclusions in light of the observational nature of the study, describing the observed observations without over-interpretation.Undoubtedly, the era of big data has arrived for atrial fibrillation studies, but, until now, had not reached the arena of atrial fibrillation ablation12. In their paper, Mills and colleagues give us much to think about both in terms of using large datasets to study AF ablation and, of course, of the potential to reduce bleeding complications through the use of VCDs.References1. Mark DB, Anstrom KJ, Sheng S, et al. Effect of Catheter Ablation vs Medical Therapy on Quality of Life Among Patients With Atrial Fibrillation: The CABANA Randomized Clinical Trial. JAMA. 2019;321(13):1275-1285.2. Asad ZUA, Yousif A, Khan MS, Al-Khatib SM, Stavrakis S. Catheter Ablation Versus Medical Therapy for Atrial Fibrillation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Circ Arrhythm Electrophysiol. 2019;12(9):e007414.3. Benali K, Khairy P, Hammache N, et al. Procedure-Related Complications of Catheter Ablation for Atrial Fibrillation. Journal of the American College of Cardiology. 2023;81(21):2089-2099.4. Wynn GJ, Haq I, Hung J, et al. Improving safety in catheter ablation for atrial fibrillation: a prospective study of the use of ultrasound to guide vascular access. J Cardiovasc Electrophysiol. 2014;25(7):680-685.5. Voskoboinik A, Sparks PB, Morton JB, et al. Low Rates of Major Complications for Radiofrequency Ablation of Atrial Fibrillation Maintained Over 14 Years: A Single Centre Experience of 2750 Consecutive Cases. Heart Lung Circ. 2018;27(8):976-983.6. Ikenouchi T, Takigawa M, Goya M, Kudo T, Sasano T. Refractory Deep Vein Thrombosis Caused by Femoral Vein Stenosis Due to Suture-Medicated Vascular Closure Device. Int J Angiol. 2023;32(4):288-291.7. Virk SA, Ariyaratnam J, Bennett RG, Kumar S. Updated systematic review and meta-analysis of the impact of contact force sensing on the safety and efficacy of atrial fibrillation ablation: discrepancy between observational studies and randomized control trial data. EP Europace. 2018;21(2):239-249.8. Harrison SL, Buckley BJR, Austin P, Lane DA, Lip GYH. Catheter ablation and lower risk of incident dementia and mortality in older adults with atrial fibrillation. J Am Geriatr Soc. 2023;71(11):3357-3366.9. Castro-Urda V, Segura-Dominguez M, Jimenez-Sanchez D, et al. Efficacy and safety of Proglide use and early discharge after atrial fibrillation ablation compared to standard approach. PROFA trial. Pacing Clin Electrophysiol. 2023;46(7):598-606.10. Tilz RR, Feher M, Vogler J, et al. Venous vascular closure system vs. figure-of-eight suture following atrial fibrillation ablation: the STYLE-AF Study. Europace. 2024;26(5).11. Jackson N, McGee M, Ahmed W, et al. Groin Haemostasis With a Purse String Suture for Patients Following Catheter Ablation Procedures (GITAR Study). Heart Lung Circ. 2019;28(5):777-783.12. Perez MV, Mahaffey KW, Hedlin H, et al. Large-Scale Assessment of a Smartwatch to Identify Atrial Fibrillation. New England Journal of Medicine. 2019;381(20):1909-1917.