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Welcome to EP Edge Journal Watch — where cardiac electrophysiology meets evidence, precision, and perspective.
Hosted by Dr. Niraj Sharma, this bi-weekly podcast distills high-impact cardiovascular and EP research into clear, clinically meaningful insights. Each episode goes beyond headlines and abstracts to uncover what new studies actually mean for patient care, decision-making, and the future of electrophysiology.
What EP Edge Journal Watch stands for:
Evidence-based practice
Precision electrophysiology
A forward-thinking, edge-driven approach to how we interpret and apply data in real-world clinical settings.
Whether you’re an electrophysiologist, cardiologist, researcher, trainee, or allied health professional, EP Edge Journal Watch brings you the signal — not the noise. Expect sharp summaries, thoughtful commentary, and practical takeaways designed for the busy clinician who wants to stay ahead of the curve
This program is for educational purposes only and reflects independent editorial commentary. It is not medical advice and should not replace clinical judgment or review of primary sources and guidelines. The views expressed are those of the host and contributors.
Niraj Sharma:Hello and welcome back to EP Edge Journal Watch. I'm Doctor. Sharma and I'm very glad you're here. This is Issue 20 from April 2026 and this month's theme is one that feels very current in electrophysiology: screening precision, expansion of pulse field ablation, and device strategy in transition. Across this issue, the real question is not simply whether a technology works in principle.
Niraj Sharma:The more important question is whether it changes the clinical trade off in a meaningful way. Does it change diagnosis? Does it improve durability? Does it reduce complications? Does it simplify workflow without giving away efficacy?
Niraj Sharma:Or does it just create a new kind of complexity? We'll start with atrial fibrillation screening, first with the Apple Watch, then with electrocardiogram based artificial intelligence. After that, we'll move through defibrillator strategy, CRT and AV node ablation, leadless atrial pacing, pulsed field expansion into flutter ablation, newer catheter platforms for pulmonary vein isolation, and finally anticoagulation timing after ablation. As we go, I'll keep the statistics practical and clinically readable. Whenever I mention a hazard ratio, odds ratio, or absolute risk difference, I'll explain what it means rather than just reciting the number.
Niraj Sharma:Let's begin with the equal trial because it captures a very modern clinical problem. Atrial fibrillation is often paroxysmal, often silent, and often absent when the patient is sitting in front of us in clinic. So the challenge is not only finding rhythm data. The challenge is building a pathway that turns a device alert into a diagnosis that actually changes management. The EACL trial tested whether six months of Apple Watch based monitoring, combining photoplethysmography and single lead electrocardiography, could improve atrial fibrillation detection compared with standard care in older patients at elevated stroke risk.
Niraj Sharma:This was a prospective multicenter randomized controlled trial in The Netherlands. Four thirty seven patients were randomized, two nineteen went to smartwatch screening, and two eighteen went to standard care. Importantly, these were not low risk wellness users. These were patients aged 65 or older with increased stroke risk and no prior atrial fibrillation. The watch itself was only part of the intervention.
Niraj Sharma:All smartwatch electrocardiograms were reviewed remotely by an adjudication team within twenty four hours. That point is essential because this was not a consumer gadget floating in the wild. It was integrated into an actual clinical workflow. Now the results. New onset atrial fibrillation occurred in nine point six percent of the intervention group and two point three percent of the control group.
Niraj Sharma:The absolute risk difference was seven point three percentage points. That means that if you screened 100 similar high risk patients this way, you would diagnose about seven additional patients with atrial fibrillation compared with usual care. The hazard ratio was 4.4, with a 95% confidence interval from 1.66 to 11.66. In practical language, the screened group had more than four times the hazard of atrial fibrillation detection over the study period and because the confidence interval stayed fully above one, that difference was statistically significant. Several asymptomatic episodes were detected only in the intervention arm.
Niraj Sharma:That matters because those are exactly the patients traditional clinic based care tends to miss. But the paper also gives us a very realistic caution. Among thirty seven patients with at least one Apple Watch electrocardiogram labeled as atrial fibrillation, only twenty were clinically confirmed. That gives a positive predictive value of fifty four percent. Positive predictive value is a simple but important concept.
Niraj Sharma:It tells you if the device says atrial fibrillation, how often that signal turns out to be truly atrial fibrillation after clinical review. Here, it was just over half, so the watch was useful but it was not acting as a definitive diagnostic instrument by itself. Emergency department visits and major adverse cardiovascular events were low and similar between groups. So this is a diagnosis paper, not an outcomes paper. It tells us the pathway finds more atrial fibrillation.
Niraj Sharma:It does not yet tell us whether this leads to fewer strokes, fewer admissions, or better long term prognosis. The limitations are worth sitting with for a moment. First, the trial was open label, which is difficult to avoid in a device based screening study. Second, it was performed in two secondary care centers, so generalizability to broader primary care or less structured health systems is uncertain. Third, the endpoint was detection, not hard clinical events.
Niraj Sharma:Now the EP Edge take equal matters because it validates a pathway more than it validates a piece of hardware. The real intervention was not just the Apple Watch. It was the combination of wearable detection, rapid rhythm capture, and human adjudication. That closed loop is why the signal turned into diagnoses rather than noise. For practice, the takeaway is that wearables can be clinically meaningful, but only when attached to a system that can review, confirm, and act.
Niraj Sharma:Without that infrastructure you may simply increase alerts. With that infrastructure you may actually improve case finding in the patients who matter most. That brings us naturally to the next paper, the Vital AF Trial Analysis Using Electrocardiogram Based Artificial Intelligence Risk Models. The key idea here is very appealing. If broad age based screening gives inconsistent returns, perhaps the problem is not the screening tool.
Niraj Sharma:Perhaps the problem is that we are screening too many people with a low pretest probability of atrial fibrillation. This analysis looked at sixteen thousand nine hundred and thirty seven vital AF participants without prevalent atrial fibrillation who also had a recent twelve lead electrocardiogram. The investigators compared three risk models: CHARGE AF, which is a clinical score, ECG AI, which is a deep learning model based on the 12 lead electrocardiogram, and CHAI which combines the two. All three models predicted incident atrial fibrillation over two years, but the combined model performed best overall. The study looked not only at discrimination, meaning how well the model separates higher risk from lower risk people, but also at what happened when actual screening was applied across risk strata.
Niraj Sharma:In the top decile of CHAI risk, the atrial fibrillation diagnosis rate was ten point zero seven per one 100 person years in the screened group and seven point seven six per 100 person years in the control group. That is a rate difference of two point three two per 100 person years. Again, let's translate that. A difference of two point three two per 100 person years means a little more than two extra diagnoses each year for every one hundred high risk individuals screened. Expressed differently, the number needed to screen was forty three per year.
Niraj Sharma:So for every forty three very high risk patients screened for one year, one extra case of atrial fibrillation was diagnosed, and the signal became even more efficient in the top five percent of risk, where the effect corresponded to about one extra diagnosis for every twenty three people screened per year. That is the central message of this paper: Screening intensity matters but screening selection may matter even more. Now a few statistical notes. The paper also showed that the combined CHAI model discriminated incident atrial fibrillation better than the traditional clinical score alone. In other words, adding electrocardiogram based artificial intelligence to the clinical model sharpened risk stratification.
Niraj Sharma:The practical consequence is that you may be able to direct screening resources toward a smaller group with a much higher yield, but the limitations are equally important. This was a post hoc analysis, not a prospective trial in which patients were randomized according to AI defined risk. Only patients with an available recent twelve lead electrocardiogram could be included, and once the investigators adjusted for study practice, the interaction weakened. That tells you something very important: systems level factors such as access, workflow, and care environment may still shape the apparent screening benefit. The EP Edge take is that this paper pushes atrial fibrillation screening away from age alone and toward precision selection.
Niraj Sharma:It supports the editorial point that who gets screened may matter more than how aggressively screening is performed. For practice today, I would not treat CH AI as a universal plug and play screening mandate, but I would absolutely view it as a credible framework for future primary care screening pathways. The next step is not simply better discrimination, The next step is proving that AI guided detection changes downstream management and outcomes, not just diagnosis counts. So together, equal and vital F tell a coherent story. The future of screening is not one watch and not one algorithm.
Niraj Sharma:It is targeted patient selection, accessible rhythm capture, and a reliable system for adjudication. Let's now move from screening to device trade offs, starting with inappropriate shocks in subcutaneous versus transvenous implantable cardioverter defibrillators. This analysis pooled patient level randomized data from the PRETORIAN and ATLAS trials, for a total of thirteen forty two patients. The question was very practical: in the modern era, how much inappropriate shock risk do we accept in exchange for avoiding transvenous hardware? The primary endpoint was time to first inappropriate shock over a median follow-up of three point five years.
Niraj Sharma:First inappropriate shocks occurred more often with the subcutaneous system (8.5 percent versus five point four percent), Expressed as event rates, that was two point five versus one point five per 100 patient years. The hazard ratio was 1.61, with a 95% confidence interval from 1.06 to 2.45, so the relative hazard was about 61% higher with the subcutaneous device, but the absolute rate remained low overall, and that is an important counseling point. This is not a story of frequent device failure, It is a story of a meaningful but still numerically modest trade off. The mechanism analysis is where the paper becomes especially useful. Subcutaneous devices had more inappropriate shocks due to cardiac over sensing and due to electromagnetic interference or myopotentials.
Niraj Sharma:The hazard ratio for over sensing related shocks was very high (over fifteen), although the confidence interval was wide, which tells you the count of such events was relatively small. Transvenous systems, by contrast, had more inappropriate shocks driven by atrial arrhythmias. The overall inappropriate ICD therapy endpoint, which included anti tachycardia pacing, was not significantly different. So the difference is not just more therapy overall, it is a difference in the type and mechanism of inappropriate therapy. The limitations should temper overstatement.
Niraj Sharma:Adjudicators were not blinded to device assignment. Device generations evolved during follow-up. The Smart Pass algorithm was introduced during the study period, and mechanism specific event counts were relatively small. Still, the EP Edge take is strong. The subcutaneous ICD is not disqualified by this study.
Niraj Sharma:Instead, its trade off is now better defined. If the main benefit is avoiding transvenous leads and long term lead related problems, that benefit remains real, but if the individual patient is someone for whom over sensing driven inappropriate shocks would be especially destabilizing, then that trade off may matter more. In other words, this is no longer a generic device preference discussion. It is a mechanism based counseling discussion. Now let's move to another assumption that has been widely held in electrophysiology that AV node ablation should usually improve outcomes in CRT recipients with permanent atrial fibrillation if it increases biventricular pacing.
Niraj Sharma:The CAA NAF trial directly tested that assumption. It was an international multicenter randomized trial comparing AV node ablation with medical rate control in patients with reduced ejection fraction, permanent atrial fibrillation, and CRT defibrillator systems. One hundred and forty three patients were randomized, sixty seven to AV node ablation, and seventy six to medical rate control. The trial was stopped early for futility. The primary endpoint was the composite of all cause mortality and non fatal heart failure events.
Niraj Sharma:There was no significant difference, forty seven events in the ablation arm versus forty six in the medical arm. The incident rate ratio was one point one six, with a 95% confidence interval from 0.6 to 2.24. There were also no significant differences in cardiovascular mortality, unplanned hospitalizations, ventricular arrhythmias requiring device therapy, six minute walk distance, or quality of life scores. Yet the biventricular pacing percentage was clearly higher in the ablation arm at final follow-up, ninety eight percent versus eighty seven point four percent. And that is exactly why this study is so important.
Niraj Sharma:It tells us that a more favorable device metric does not automatically produce a better clinical outcome if the baseline problem is not severe enough for that metric to be the dominant driver. The limitations are substantial and must be acknowledged. This was a small study terminated early, so the confidence intervals are wide. The population was relatively well rate controlled at baseline with decent pacing percentages already, so these findings should not be over generalized to the patient with truly chaotic ventricular conduction, very poor pacing delivery, or recurrent heart failure clearly linked to AF rate control failure, but the EP Edge take is clear. Atrioventricular node ablation should not be treated as a reflexive or default escalation simply because patient has CRT and permanent atrial fibrillation.
Niraj Sharma:It remains a strategic tool. Use it when the clinical problem is failed rate control or failed pacing delivery, not just to improve an interrogation number. Staying with devices, let's turn to leadless atrial pacing for sinus node dysfunction. The ARRIVE real world study compared the AVEAR AR atrial leadless system with both dual chamber and right atrial transvenous pacing systems in a Medicare population. This was a large claims based observational analysis, not a randomized trial and that matters.
Niraj Sharma:But after overlap waiting for baseline differences, the results were clinically compelling. Thirty day complications were lower with AV or AR than with dual chamber transvenous pacing, adjusted six point seven percent versus nine point four percent. At one year, overall complications were three point six percent versus eight point five percent, with an adjusted hazard ratio of zero point four. That means roughly a sixty percent lower relative hazard of complications in the leadless group. The leadless system also had lower reintervention rates compared with both dual chamber and right atrial transvenous systems.
Niraj Sharma:Importantly, one year mortality was similar across groups. The conceptual point is simple. This is not a mortality advantage story. It is a hardware burden story. Fewer leads and no pocket should translate into fewer lead failures, fewer dislodgements, fewer pocket issues, and fewer revisions.
Niraj Sharma:And that is exactly the signal seen here. The limitations remain those of all claims based observational work: residual confounding, inability to directly assess pacing burden, symptom burden, or conduction physiology, and limited generalizability beyond the Medicare population. Even so, the EP Edge take is that atrial leadless pacing is now a serious frontline option in selected sinus node dysfunction patients with intact atrioventricular conduction, especially when the long term cost of transvenous hardware is the main concern. Now we move into the Pulsed Field Ablation Cluster, which is one of the most dynamic parts of this issue. First the advantage: AF sub study comparing pulse field and radiofrequency ablation for the CT isthmus.
Niraj Sharma:This study matters because it tackles one of the main concerns about extending pulsed field ablation into the right atrium: coronary vasospasm. In the clinical comparison, fifty patients had CTI ablation with radiofrequency and one hundred and forty one had CTI ablation with linear bipolar pulsed field ablation. Before PFA at the CTI, the protocol used vasopressor support followed by intravenous nitroglycerin. The purpose was to reduce the risk of right coronary spasm. The efficacy results were excellent and essentially equivalent.
Niraj Sharma:Acute CTI block was one hundred percent with radiofrequency and ninety eight point six percent with pulsed field ablation. Freedom from recurrent typical flutter at three sixty days was ninety eight point zero percent versus ninety seven point nine percent. So on efficacy, the two approaches were practically indistinguishable. The workflow difference, though, was large. Median CTI ablation time was five minutes with pulsed field ablation and fourteen minutes with radiofrequency.
Niraj Sharma:That is a very meaningful efficiency gain in the lab. And importantly, with the nitroglycerin protocol, there was no clinical manifestation of coronary spasm. The limitations are worth respecting. This was not a randomized comparison. The two groups came from different phases of the larger ADVantage program and all cases were embedded inside persistent AF ablation procedures, not isolated flutter only practice.
Niraj Sharma:Still, the EP Edge take is that PFA at the CTI is no longer theoretical. With a deliberate coronary protection strategy, it appears operationally efficient and clinically effective. The remaining questions are long term coronary safety, cost, and where exactly this fits among growing catheter choices. Now compare that with the linear randomized trial, which stayed within radiofrequency but changed the catheter design. This trial compared a lattice tip radiofrequency catheter with a standard irrigated focal tip catheter for CTI ablation and used an unusually rigorous acute endpoint.
Niraj Sharma:Bi directional block persisting after 60minutes confirmed by high density mapping and adenosine testing. The reason that endpoint matters is that standard differential pacing can falsely reassure us. You can think you have bidirectional block when in fact residual endocardial slow conduction or epicardial bridging is still present. High density mapping exposes that problem. Under those strict conditions, the lattice tip catheter performed extremely well.
Niraj Sharma:The primary endpoint was achieved in ninety four point one percent of lattice tip cases compared with sixty eight point six percent of standard focal tip cases. First pass block was ninety point two percent versus sixty point eight percent. Ablation time dropped about forty five seconds to forty one seconds and the number of lesions also dropped significantly. In plain language, the lattice tip catheter created a more reliable acute CTI line, more quickly and more often on the first pass. The study does have limits.
Niraj Sharma:It is an acute endpoint study without long term recurrence follow-up. A substantial proportion of patients had CTI ablation as part of a broader AF workflow rather than for isolated documented flutter alone, and the study was not powered to detect rare complications. The EP Edge take is that even in a mature radiofrequency territory like CT ablation, catheter design still matters. Linear improves acute procedural confidence. What we still need is longer term confirmation that this acute advantage becomes a durable rhythm advantage.
Niraj Sharma:From CTI linear work, let's go back to pulmonary vein isolation and PFA platform differentiation. The PULSAR trial evaluated a spherical multi electrode pulsed field system for symptomatic drug refractory paroxysmal atrial fibrillation in a multicenter FDA investigational study. In the pivotal cohort of one hundred and sixty four patients, the primary safety event rate was zero point six percent, with one hemorrhagic stroke and no device related primary adverse events. There was no moderate or severe pulmonary vein narrowing in the stenosis sub study. Primary twelve month effectiveness was seventy seven point eight percent, with a ninety five percent confidence interval from 70.6 to eighty three point nine percent, but the statistic that really stands out is pulmonary vein durability at redo.
Niraj Sharma:In 11 redo procedures, 39 of 41 veins or ninety five point one percent remained isolated. That is a very strong per vein durability signal, even though it came from a small subset. The EP Edge take for PULSAR is that this is not merely another fast pulse field catheter story. It is a lesion quality story. If the durability signal holds in broader practice, the differentiator is not the novelty of the platform.
Niraj Sharma:It is the reproducibility of durable pulmonary vein isolation. The obvious caution is that this was a single arm sponsor supported trial, and the durability estimate came from a limited redo population. So we should be enthusiastic but not casual. The companion real world perspective comes from VERIPURE, a large prospective post market observational study of the variable loop circular pulse field catheter across 22 European centers. More than one thousand patients underwent first time atrial fibrillation ablation.
Niraj Sharma:Acute procedural success was achieved in ninety nine point eight percent. Primary adverse events occurred in zero point eight percent of evaluable patients. That included two tamponade or perforation events, four major vascular access or bleeding events, one thromboembolism, and one pericarditis event. There was no stroke, no transient ischemic attack, no coronary spasm, and no acute kidney injury reported. At interim twelve month extraction, four forty two patients had completed follow-up.
Niraj Sharma:Estimated freedom from atrial arrhythmia recurrence was eighty four point two percent overall, ninety point five percent in paroxysmal atrial fibrillation, and seventy five point three percent in persistent atrial fibrillation. Those are very respectable real world numbers, but they are interim numbers. Not everyone had completed one year, there was no comparator arm, the flow rates not defined, and the analysis was descriptive rather than inferential. Also, some workflow details, including irrigation flow rates early in the experience, were not fully captured. So the EP Edge take is measured optimism.
Niraj Sharma:Veripure suggests that this platform keeps its workflow and safety credibility outside the registrational setting. The full cohort maturation will tell us whether the early real world signal stays durable. If you step back, PULSAR and VERIPURE together tell us something broader. The pulsed field era is moving beyond novelty. Platforms are now being judged on durability, lesion reproducibility, workflow efficiency and how they behave outside curated trials.
Niraj Sharma:Our last paper is conceptually different but extremely relevant in daily practice. When should oral anticoagulation be discontinued after an apparently successful atrial fibrillation ablation? The Iwawaki study retrospectively analyzed two thousand four hundred and forty eight patients undergoing first atrial fibrillation ablation. The investigators used inverse probability weighting and a landmark analysis across hundreds of time points to model the balance between thromboembolic risk and bleeding risk if anticoagulation was stopped at different times after ablation. They then used what they called a reverse net clinical benefit framework.
Niraj Sharma:Usually net clinical benefit is framed around continuing anticoagulation. Here they flipped the question and asked when the bleeding advantage of stopping anticoagulation begins to outweigh the thromboembolic penalty. The model's peak occurred at eight point one months after ablation. That is the headline result. But here is how it should be interpreted.
Niraj Sharma:It does not mean that eight point one months is the new universal stopping rule. In fact, at that time point, stopping anticoagulation was associated with lower major bleeding risk but also with higher thromboembolic risk, and there was no significant mortality difference. So what the paper really shows is that the two risk curves move differently over time. Bleeding risk falls as discontinuation is delayed. Thromboembolic risk rises if anticoagulation is stopped too early.
Niraj Sharma:The relationship is dynamic, not static. The limitations are substantial. This was a single center retrospective analysis. The eight point one month estimate is model derived, not prospectively validated. Recurrence monitoring was not continuous, so silent residual atrial fibrillation burden may have been underestimated.
Niraj Sharma:And patients who stop anticoagulation are often fundamentally different from patients who continue it, even after statistical adjustment. The EP Edge take is that this is a hypothesis generating paper that usefully exposes the weakness of our current calendar driven approach. It does not replace individualized decision making, but it makes clear that post ablation anticoagulation cannot be reduced to a simple ritual of continue two or three months, then decide. Let me close with a quick recap of the entire issue. The EEQUAL trial showed that wearable atrial fibrillation detection becomes clinically meaningful when the device is embedded inside a real adjudication and response pathway, not when it is left to operate alone.
Niraj Sharma:The VITAL F risk analysis showed AI based electrocardiogram screening is most useful when it enriches the population being screened, particularly in the highest risk deciles, rather than simply screening all older adults the same way. The pooled Pre Torian and ATLAS analysis clarified the modern subcutaneous ICD trade off: fewer lead related liabilities but more over sensing related inappropriate shocks, while transvenous systems remain more vulnerable to atrial arrhythmia driven inappropriate therapy. CAA NAF reminded us that AV node ablation in CRT recipients with permanent atrial fibrillation should be a strategic choice, not an automatic reflex, especially when the patient is already reasonably rate controlled. The ARRIVE leadless atrial pacing study showed that AVER AR delivered fewer complications and fewer reinterventions than transvenous systems at one year, making atrial leadless pacing a serious frontline consideration in selected sinus node dysfunction patients. The advantage: AF sub studies showed that pulsed field ablation can now credibly and efficiently reach the CTI when coronary spasm prevention is handled deliberately.
Niraj Sharma:The linear randomized trial suggested that even within radiofrequency technology, catheter design still matters for acute CTI line integrity and procedural efficiency. PULSAR and VERIPURE together strengthen the idea that next generation pulsed field systems will increasingly be judged by durability and reproducibility, not simply by speed or novelty, and the Iwawaki analysis reminded us that anticoagulation after ablation remains a biologic and patient specific decision, not just a date on the calendar. All references and graphics are available on the LinkedIn newsletter EP Edge Journal Watch as well as on Substack at epedge. Substack . com. Email questions or concerns to epedgecast@gmail . com
Niraj Sharma:Thank you very much for listening. I am Doctor. Sharma, take care and I'll see you in the next episode. Bye for now.