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.

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.

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.

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.

Introduction: The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to a transvenous ICD in patients who meet criteria for ICD implantation without concurrent need for cardiac pacing. The objective of this study is to examine the rates of and indications for S-ICD removal and extraction. Methods: A retrospective analysis of all patients who underwent S-ICD implantation between 2010 and 2022 at a single multihospital healthcare system was performed. The primary endpoint was S-ICD removal or extraction. Patient and device characteristics were abstracted from the electronic medical record. Univariate and multivariate analyses were completed to determine factors associated with S-ICD extraction. Results: A total of 372 patients (69.5% male; 48.6 ± 14.4 years old) underwent S-ICD implantation during the study period. There were 22 (5.9%) patients (81.8% male; 52.1 ± 13.2 years old) who underwent S-ICD extraction over a median follow up period of 4.4 [2.0-6.5] years. The median length of time between implantation and extraction was 39.6 [8.3-64.6] months. The most common indications for S-ICD extraction were need for bradycardia pacing (incidence, 1.08%), infection (1.34%), and inappropriate shocks due to oversensing (1.34%). A smoking history and higher body mass index were independently associated with S-ICD extraction. Conclusions: The overall rate of S-ICD extraction over 4.4 [2.0-6.5] years was 5.9%, with the most common indications for extraction being need for bradycardia pacing, infection, and inappropriate shocks due to oversensing. A smoking history and high body mass index are associated with increased rates of S-ICD extraction. With appropriate patient selection for the S-ICD, the need to remove the device after implantation is low.

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.