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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
Hi everyone, I'm Doctor. Sharma and welcome back to EP Edge Journal Watch. Before we begin, thank you to all of you who keep sending emails, comments and suggestions. I really do appreciate that. The feedback helps me decide what to emphasize, what to clarify and where to go deeper.
Niraj Sharma:In this issue we have a broad and very interesting set of papers. Some are immediately practice facing, some are mechanistic, some are hypothesis generating, and some remind us that electrophysiology sits inside a much larger cardiovascular ecosystem. We begin with intravenous amiodarone in pre excited atrial fibrillation. This study was done because many of us were trained with a near absolute warning: If a patient has pre excited AF, do not use amiodarone. That warning came from the concern that nodal slowing could shift more conduction down the accessory pathway, shorten the pre excited RR interval, and potentially tip the patient into ventricular fibrillation.
Niraj Sharma:But the authors asked an important question: Is that teaching truly grounded in population level evidence or has it been amplified by a small case report literature? Methodologically, this was a systematic review covering 12 studies and 177 patients. The dataset included case reports, observational cohorts, and before and after interventional studies. Importantly, the authors did not stop at narrative review. They also used Bayesian beta binomial modeling in the cohort and interventional data set to estimate the probability of ventricular fibrillation after intravenous amiodarone in electrocardiographically confirmed pre excited AF.
Niraj Sharma:They also reviewed electrophysiology data on refractoriness and surveyed emergency centers in Latin America to understand the real world availability of alternatives such as procainamide and ibutalide. The result was more nuanced than the traditional story. A handful of case reports did describe acceleration or ventricular fibrillation, but across the larger cohort and interventional studies there was no observed ventricular fibrillation and the posterior mean risk estimate remained very low. The EP studies actually showed prolongation of refractoriness in both the AV node and the accessory pathway, and one of the most practical findings was that the preferred alternatives were often not available in the emergency departments that were surveyed, whereas intravenous amiodarone was. So what is the EP Edge take?
Niraj Sharma:This paper is practice challenging but not practice changing. It softens the absolutist historical narrative, especially in resource limited environments, but it does not make amiodarone first line therapy for stable pre excited AF. If the patient is unstable, synchronized cardioversion remains the answer. If the patient is stable and you are pursuing pharmacologic therapy, ibutilide or procainamide still fit best with the current physiologic and guideline based approach. What this paper really does is remind us to separate dogma from data.
Niraj Sharma:In practice, this is not a green light to casually reach for amiodarone. It is a reminder that the real world context matters, especially when the textbook drug is simply not on the shelf. The second study is NurseCat AF and this is one of the most quietly important papers in the issue. Why was it done? Because ablation outcomes are too often discussed as if the catheter alone deserves the credit, but anybody who actually follows AF patients longitudinally knows that education, expectation setting, symptom interpretation, follow-up access, weight, sleep apnea, tobacco exposure, and physical activity all shape what happens after the procedure.
Niraj Sharma:This was a single center randomized clinical trial of 66 patients undergoing a first AF ablation. Patients were assigned either to usual care or to a structured nurse led pathway that included education before ablation, periprocedural preparation, early follow-up, later follow-up, and active risk factor work. The primary endpoint was quality of life at twelve months using the ASTA scale and the secondary endpoints included recurrence, emergency visits, readmissions, symptom burden, patient knowledge, satisfaction, and risk factor optimization. The signal was strong. The nurse led arm had meaningfully better quality of life, less recurrence, fewer emergency visits, less symptom burden, better patient understanding, and better modification of practical risk variables such as smoking, activity, weight, and sleep apnea identification.
Niraj Sharma:And that matters because this was not a tiny cosmetic improvement. The effect size for the primary endpoint was large enough to suggest real clinical relevance. My EP EdgeTake is that this is one of the most implementable papers in the issue. It argues that part of what we casually call ablation success may actually be pathway success. In practice it supports building more disciplined periablation care pathways rather than focusing only on lesion technology.
Niraj Sharma:Better systems may give you better rhythm outcomes. Next is left bundle branch area anti tachycardia pacing compared with conventional right ventricular ATP. This is a mechanistic study but an exciting one. The underlying question is elegant. If conventional ATP is delivered from the RV and activates the ventricle relatively non physiologically, could conduction system delivery engage the Purkinje network earlier and interrupt VT more efficiently?
Niraj Sharma:This was not a human clinical trial. It was a preclinical canine ischemia reperfusion model with both right ventricular pacing from the apex and left bundle branch area leads connected to ICDs. Across six analyzable animals, the investigators treated 79 VT episodes and used careful statistical methods to account for clustering within animals. They also mapped the sequence of Purkinje activation and myocardial capture to understand not just whether ATP worked but why it worked. The results favored left bundle branch area ATP.
Niraj Sharma:Termination was more frequent. There was no obvious increase in acceleration or induced ventricular fibrillation and the activation data showed earlier Purkinje engagement and earlier myocardial activation with conduction system delivery. In other words, the physiologic signal matched the clinical signal. The therapy seemed not only more effective but more intelligently delivered. The EP Edge take is that this is beautiful mechanistic work, but it remains hypothesis generating.
Niraj Sharma:We are not ready to reprogram human ICDs based on a small animal study. Still, this paper points toward a future in which conduction system leads may become dual purpose platforms, pacing when needed and delivering smarter ATP when VT occurs. In practice right now, it mainly changes how we think rather than how we program. Now let's move to one of the most conceptually disruptive papers in the issue: varenicline for ventricular ectopy after myocardial infarction. Varenicline is a medication best known for helping patients quit smoking.
Niraj Sharma:It works as a partial agonist at nicotinic acetylcholine receptors, a pathway that may also influence cardiac electrical activity. This study matters because the CAST lesson still hangs over every antiarrhythmic discussion in the post MI population. We learned the hard way that suppressing ectopy is not enough if the therapy increases malignant arrhythmias or mortality, so when a therapy appears to suppress PVCs through a different biologic pathway, the right response is interest but disciplined interest. This was a randomized, double blind, placebo controlled phase II proof of concept study. Adults at least four weeks after myocardial infarction with frequent premature ventricular complexes on extended ambulatory monitoring were assigned to varenicline or placebo for forty five days on top of standard therapy.
Niraj Sharma:The primary endpoint was percentage change in twenty four hour PVC count and key secondary endpoints included a 50 responder rate and the incidence of non sustained ventricular tachycardia. The treatment effect was striking. Varenicline produced a substantially greater reduction in PVC burden, a much higher responder rate, and less non sustained VT. There were no deaths or malignant ventricular arrhythmias in the active treatment arm during the study period. But here is the crucial point: the endpoint was still a surrogate endpoint.
Niraj Sharma:PVC suppression is not the same thing as improved survival, fewer shocks, or less sustained VT in the long run. My EP Edge take is that this is biologic proof of concept with a reassuring early safety signal, not yet a treatment recommendation. If future trials show durable benefit without proarrhythmia, this could represent a genuinely new antiarrhythmic class, one not built around the classic sodium or potassium channel paradigm. In practice today, it should stimulate curiosity and future trial design, not routine prescribing for post miectopy. The fifth paper is the first clinical experience with reversible electroporation mapping in atrial flutter, sometimes referred to as PFREV or pulse field reversible mapping.
Niraj Sharma:Why was this done? Because in complex flutter, we often face a tension between diagnostic certainty and tissue destruction. We want to know whether we are on critical tissue, but the usual way to prove that may involve committing to ablation. In this first inhuman feasibility experience, the investigators used a lattice tip catheter in reentrant atrial tachycardias and delivered reversible electroporation pulses at different points within and outside the circuit. They compared the response to conventional high density activation and entrainment mapping, which served as the reference standard for the critical isthmus.
Niraj Sharma:They then categorized the effects of the pulses: termination, stable cycle length prolongation, transient irregularity, or no effect. The key message was specificity. When PFREV or pulse field reversible mapping caused termination or stable tachycardia that signal was highly specific for critical tissue, and termination occurred only in the critical isthmus. Sensitivity, however, was modest, meaning a negative response could not reliably exclude critical involvement. So the EP Edge take is very practical.
Niraj Sharma:A positive PFR EV signal appears highly informative. A negative one is not. That means this technique looks less like a standalone replacement for mapping and more like a very useful adjunct when conventional mapping leaves some uncertainty. In practice, it may eventually help reduce unnecessary ablation by increasing confidence before irreversible energy is delivered. Next is the factor XI inhibitor abalaxumab versus factor X inhibitor rivaroxaban in older individuals with atrial fibrillation from the age based analysis of Azalea Timmy 71.
Niraj Sharma:This study was done because older AF patients are where anticoagulation becomes hardest. Stroke risk climbs, but bleeding risk often climbs faster. If factor XI inhibition is going to matter clinically, this is exactly where it should matter. This was a pre specified age analysis from a phase IIb randomized trial. More than twelve hundred AF patients were assigned to monthly subcutaneous abalacumab at one of two doses or to daily rivaroxaban.
Niraj Sharma:About six twenty five patients were 75 years of age or older. The primary focus was major or clinically relevant non major bleeding. Examined both by age category and across age as a continuous variable. The message was consistent and clinically important. In the older cohort, bleeding was substantially lower with abalacumab than with rivaroxaban.
Niraj Sharma:The relative reduction was maintained across aged strata, and the absolute benefit appeared greater in older patients because the bleeding curve in the rivaroxaban arm rose with age, whereas the abalacumab curve remained comparatively flat. The EP Edge take is that the safety side of the factor XI story is becoming increasingly persuasive, especially in the older AF population that makes clinicians most uneasy about bleeding, but we have to keep the sentence attached to these results. Efficacy for stroke prevention still requires phase III confirmation. In practice, this paper does not replace factor X inhibitors today, but it makes the future anticoagulation landscape look very different. The seventh study is device assisted versus standard Valsalva for terminating supraventricular tachycardia.
Niraj Sharma:The rationale is straightforward. The Valsalva maneuver works, but in routine care it is often performed poorly. So the investigators asked a simple but smart question: If patients are helped to generate and maintain the target strain pressure, can a familiar first line maneuver work better? This was an open label randomized EP lab study in induced AV nodal reentry and AV reentry tachycardia. Two ten patients completed the assigned maneuver, either a standard Valsalva or a device assisted version, with up to two attempts allowed.
Niraj Sharma:The endpoint was simple and clinically relevant: returned to sinus rhythm within one minute. The difference was large: device assisted Valsalva converted a substantially higher proportion of patients after one attempt and after two attempts. Even among patients who initially failed standard Valsalva, rescue with the device worked often enough to make the result hard to dismiss as statistical noise, and there were no serious adverse events. The EP Edge take is that this is classic workflow optimization. It is not glamorous but it may be very useful.
Niraj Sharma:The main limitation is external validity because induced laboratory SVT is not the same as spontaneous SVT in the emergency department, ambulance, clinic or home and the comparator was not the modified revert style Valsalva. Even so, in practice, this supports the idea that better execution of a simple maneuver can materially improve first line SVT care. To see the device used refer to the EP Edge Journal Watch Newsletter Now to the First Reported Case of Severe Pulmonary Vein Stenosis After Pulsed Field Ablation. This paper is important not because one case changes incidence estimates, but because it changes language. PFA has rapidly developed a reputation for strong collateral safety and near immunity from clinically important pulmonary vein stenosis.
Niraj Sharma:This report reminds us that near immunity is not the same as zero risk. The case involved a 64 year old man with prior radiofrequency ablations who underwent a third procedure using a pentaspline PFA catheter. Imaging before the procedure showed only minimal narrowing of the left superior pulmonary vein. Multiple PFA applications were delivered at the left superior pulmonary vein ostium and around the ostia, and months later repeat CT and venography showed severe focal stenosis with a measurable transstenotic gradient. The obvious limitation is that this is a single case, and prior radiofrequency injury is a major confounder, So we cannot say PFA caused the stenosis by itself and we definitely cannot infer frequency.
Niraj Sharma:But the EP Edge take is still important. One case does not invalidate the broader safety story around PFA, yet it should end the use of absolutist language. In practice, redo anatomy, ostial work, extension around the veins, and cumulative lesion biology still deserve respect. The ninth paper is COBRA, comparing apixaban and rivaroxaban in acute venous thromboembolism. Why does this matter for EP?
Niraj Sharma:Because many of our patients sit right at the intersection of thrombosis, bleeding risk, frailty, and procedures. And for years clinicians have made this drug choice with surprisingly little randomized head to head evidence. COBRA was a pragmatic international randomized trial in acute symptomatic proximal DVT or significant pulmonary embolism. Patients received standard dosing of apixaban or rivaroxaban for the initial three months of treatment. The primary outcome was clinically relevant bleeding, meaning major bleeding or clinically relevant non major bleeding, with recurrent VTE and death as secondary outcomes.
Niraj Sharma:The answer was clear: Apixaban bled less than Rivaroxaban, with lower major bleeding and lower clinically relevant non major bleeding, while recurrent symptomatic VTE was essentially the same. This is one of the few papers in the issue that can change bedside default behavior almost immediately. The practical EP take is that when the question is specifically apixaban versus rivaroxaban. Apixaban now has the cleaner short term safety profile. Now the tenth paper looked at out of hospital cardiac arrest on the first working day after a holiday period.
Niraj Sharma:This is not a catheter paper but it is absolutely relevant to EP thinking. The study asked whether the return to work transition after holidays functions as a vulnerable physiologic window. Using a nationwide South Korean database with more than 200,000 weekday out of hospital cardiac arrest events, the investigators compared the first post holiday weekday with all other weekdays, and modeled incidence rate ratios across subgroups and holiday structures. The finding was modest in size but very convincing in precision, about a nine percent higher incidence of out of hospital cardiac arrest on post holiday weekdays, especially in older adults, events of cardiac origin, and patients presenting with non shockable rhythms. The signal was strongest after two or more consecutive holiday days and was concentrated in that first day back.
Niraj Sharma:The EP Edge take is that this likely reflects accumulated physiologic debt, sleep disruption, alcohol, medication lapses, delayed care seeking, and abrupt sympathetic reactivation. In practice, it argues for better holiday counseling in high risk patients and better systems awareness around these transition periods. The final item is the 2026 Multi Society Dyslipidemia Guideline and why EP clinicians should care. This was included because EP practice is no longer confined to rhythm strips and ablation endpoints. AF clinics, device clinics, and post ablation follow-up increasingly overlap with obesity, diabetes, chronic kidney disease, coronary calcium, lipoprotein and secondary prevention.
Niraj Sharma:The guideline updates the framework substantially. Prevent ASCVD replaces the older pooled cohort equations in many primary prevention settings. Lipoprotein, a measurement at least once in adulthood moves closer to routine care. ApoB has a clearer role in selected treated patients. LDL cholesterol and non HDL cholesterol goals again become more central and coronary artery calcium is used more assertively to guide treatment decisions.
Niraj Sharma:The EP Edge take is simple. Our patients are not just arrhythmia substrates, they are vascular risk substrates. So while this is not a classic electrophysiology paper, it has very real practice implications for AF clinics, LAAO pathways, and longitudinal care after procedures. In practice, some of the fastest wins may be routine capture of lipoprotein A, more disciplined statin and non statin intensification, and less undertreatment of patients with established ASCVD or incidental CAC. If I had to recap this entire issue in two sentences, it would be this: Modern electrophysiology is being reshaped not only by new tools but by smarter physiology, better care pathways, more precise bleeding risk reduction, and broader cardiovascular prevention.
Niraj Sharma:Across these papers, the common theme is that better outcomes will come from combining mechanism, judgment, and systems design rather than relying on a single technology. All references and graphics are available on the LinkedIn newsletter, EP Edge Journal Watch, as well as on Substack at epedge.substack.com. Thank you again for listening, thank you again for your emails and suggestions, and bye for now. Take care and I'll see you in the next episode.