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Welcome to EP Edge Journal Watch, where cardiac electrophysiology meets evidence, precision, and perspective.
Hosted by Dr. Niraj Sharma, this weekly podcast distills high-impact cardiovascular and Cardiac Electrophysiology and arrhythmia 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, arrhythmias analysis
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 of the host and contributors.
Niraj Sharma:Hello and welcome to EP Edge Journal Watch. I'm Doctor. Sharma. It's wonderful to have you with me for another EP Edge Journal Watch podcast. First, congratulations to Spain, world champions for the second time.
Niraj Sharma:What a composed tournament and what a finish. But my heroes were truly Cape Verde. On their World Cup debut, representing a nation of just over half a million people, They held Spain to a scoreless draw and then played their hearts out against Argentina. They were organized, fearless and absolutely determined. What a strong team.
Niraj Sharma:I'm pretty sure we'll see them at the next World Cup. Okay, back to EP. Thank you as well for your thoughtful suggestions, questions and feedback about EP Edge Journal Watch. I really do appreciate them. They help shape these conversations and keep me motivated.
Niraj Sharma:In this issue we are going to connect several stories that, at first, may seem very different: Pulsed field ablation Remote rhythm monitoring before cardioversion CaffeineWine Sudden cardiac death End tidal CO2 during resuscitation Arrhythmias in masters athletes The common question is simple: when the first signal looks persuasive, what does the evidence actually allow us to conclude? So let's get started. Let's begin with Pulsed field ablation for persistent atrial fibrillation. Pulsed field ablation has moved incredibly quickly into everyday practice. It's non thermal, relatively tissue selective, and efficient.
Niraj Sharma:Early results in paroxysmal AF have also been encouraging, but persistent AF is a tougher opponent with more advanced atrial remodeling, more non pulmonary vein triggers, and a more complex substrate. Success in paroxysmal AF can't simply be carried over. That's why the analysis from Villarreal et al. Published online in the Journal of Cardiovascular Electrophysiology in June 2026 was needed. The question wasn't can it isolate the pulmonary veins?
Niraj Sharma:We know it can. The question was can it provide durable rhythm control in persistent AF and is it better than thermal ablation? The investigators brought together 26 studies involving three thousand seven hundred and forty four patients treated with pulsed field ablation. At twelve months, the pooled estimate of freedom from atrial arrhythmia was seventy two point three percent. In practical terms, about seven out of ten patients were free from a documented atrial arrhythmia at one year.
Niraj Sharma:That's encouraging. But here's the catch: the confidence interval ran from about 69 to seventy six percent and the I2 value was seventy four percent. That tells us the studies varied substantially in their populations, lesion sets, monitoring, and recurrence definitions. So seventy two percent is a useful overall estimate. It isn't a guarantee that every center, every protocol, or every patient will achieve that result.
Niraj Sharma:Eight observational studies in the review compared pulsed field ablation with thermal ablation. The hazard ratio was 0.91 with a confidence interval from 0.78 to 1.07. What does that mean? The point estimate leans slightly toward pulsed field ablation, but the confidence interval crossed one, so the data were compatible with no meaningful difference. This analysis didn't prove superiority.
Niraj Sharma:Safety appeared favorable. But only nine studies provided comparative data. And event numbers were small. A reliable head to head safety claim isn't possible. The EP Edge take is that pulsed field ablation looks effective and operationally attractive.
Niraj Sharma:But the evidence hasn't earned the word superior. It's a highly competitive option, with success still dependent on the patient, substrate, lesion set, and monitoring. And that brings us naturally to the next question. When a patient does return after ablation, what does pulmonary vein reconnection actually look like? Delia et al.
Niraj Sharma:Addressed that question in a study published online in JACC Clinical Electrophysiology in July 2026. They studied one hundred and three patients returning for recurrent arrhythmia with pulmonary vein reconnection. Fifty had undergone pentaspline pulsed field ablation while fifty three had undergone point by point radiofrequency ablation. This wasn't a randomized durability trial, it was a selected redo population, and patients with durable isolation weren't included. The study can describe reconnection patterns but not the overall failure rate of either technology.
Niraj Sharma:The original pulsed procedures were much shorter (about fifty six minutes compared with one hundred and four minutes for radiofrequency ablation), but when these patients returned, the pattern of reconnection was quite different. After pulsed field ablation, patients had an average of 2.7 reconnected veins compared with 2.0 after radiofrequency ablation. Left sided reconnection really stood out. It was present in eighty six percent of the pulsed field group compared with forty nine percent of the radiofrequency group. Right sided reconnection, on the other hand, was nearly identical.
Niraj Sharma:But the most interesting finding was the extent of recovered conduction. The estimated gap length after pulsed field ablation was 87 millimeters compared with only 19 millimeters after radiofrequency ablation. Re isolation also took much more radiofrequency delivery, about two eighty nine seconds compared with twenty seconds, so imagine expecting one neat focal breakthrough that can be quickly tagged. After pentaspline, pulsed field ablation, recovered conduction may extend across a much broader region. That should affect the redo strategy.
Niraj Sharma:Map the entire antrum, focus on the anterior and left sided veins, use differential pacing, and don't assume the first breakthrough is the entire problem. There's a major limitation. The interval to redo was about two ten days after pulse field but twelve fifty eight days after radiofrequency, a huge imbalance that complicates direct comparison. The EP Edge take is simple. Use this study to improve how you approach a redo procedure.
Niraj Sharma:Don't use it to declare a winner in first procedure durability. Our third ablation story moves from effectiveness to real world safety, specifically the Sphere nine dual energy system. The study was led by Morgan and colleagues. It was published in the July 2026 issue of the Journal of Why was it needed? Pre approval trials used experienced centers, selected patients, and structured oversight.
Niraj Sharma:In widespread practice, rare complications and unexpected device interactions may emerge. The investigators examined the FDA's MAWD database during the first year after approval. They found two twenty two reports. Of those, 148 described clinical events and just over 100 were considered potentially catheter related. The recurring signals included VT or VF, stroke or transient ischemic attack, atrioventricular block, coronary spasm, and pericardial effusion.
Niraj Sharma:10 reports described ventricular arrhythmias associated with implanted defibrillator interactions. All 10 occurred during radiofrequency delivery, frequently during CTI ablation. The database also contained non clinical reports involving steam pops, char, and catheter entrapment. But here's the key statistical point: there's no denominator. We don't know how many SPHER-nine procedures were performed.
Niraj Sharma:Reporting is voluntary and reporting bias is unavoidable. So 30 ventricular arrhythmia reports don't represent a thirty percent rate. No incidents can be calculated. The EP Edge take is to treat this as a safety signal map. Review implanted devices, consider energy delivery near leads, and remain alert when using radiofrequency.
Niraj Sharma:A denominator based registry is needed to distinguish isolated reports from reproducible risk. Let's leave the ablation laboratory and move to the cardioversion suite. We've all seen this. A patient arrives for cardioversion. The team is ready.
Niraj Sharma:The patient has fasted and arranged transportation. Then the first rhythm strip shows sinus rhythm. The cardioversion isn't needed but the information arrived too late to save the appointment. Fernstadt and colleagues asked whether the rhythm could reach the clinic before the patient did. Their Smart Beats randomized trial was published in JAMA Cardiology in July 2026.
Niraj Sharma:They randomized two zero six patients, with two zero three in the final analysis. The intervention group performed smartphone photoplethysmography twice daily, with single lead electrocardiogram validation when needed and anticoagulation reminders. The control group received usual care. Across more than 5,200 recordings, same day cancellations fell from twenty three point two percent with usual care to four point eight percent with remote monitoring. The absolute reduction was 18.4 percentage points.
Niraj Sharma:That's the practical statistic. Monitor roughly six patients and you prevent one same day cancellation. The relative reduction was seventy nine percent, but the absolute result tells us what the program could accomplish in a real cardioversion service. Most of the benefit came from recognizing spontaneous conversion earlier. Symptoms alone weren't dependable.
Niraj Sharma:Almost twenty nine percent of monitored patients recorded sinus rhythm at least once, and about one third moved back and forth between sinus rhythm and AF or flutter. The EP Edge take is that this isn't just a wearable story, it's an information timing story. Earlier rhythm confirmation can protect capacity and reduce unnecessary fasting and travel. The next step is proving cost effectiveness in managing the data without overwhelming the clinical team. Now let's talk about a subject that always generates strong opinions: caffeine and atrial fibrillation.
Niraj Sharma:Patients are frequently told to stop coffee after an episode of AF. The advice feels intuitive. Caffeine is a stimulant, and some patients feel palpitations after drinking it. But intuition isn't evidence. And coffee isn't the same exposure as isolated caffeine, an energy drink, or a concentrated caffeine powder.
Niraj Sharma:Markus and colleagues addressed this in an American Heart Association scientific statement. It was published in Circulation in July 2026. This wasn't one new randomized trial. It reviewed evidence that's mostly observational and often studies coffee rather than caffeine itself. That matters because coffee contains other active compounds, and coffee drinkers may differ in diet, sleep, smoking, and other behaviors.
Niraj Sharma:For electrophysiologists, the most provocative randomized evidence involved habitual coffee drinkers after cardioversion. Continued daily coffee was associated with a statistically significant thirty nine percent lower risk of recurrent AF. That doesn't mean coffee prevents AF in everyone. It means the randomized evidence didn't support the assumption that coffee necessarily triggers recurrence. The observed result went in the opposite direction.
Niraj Sharma:Coffee and caffeine also don't appear to consistently increase atrial contractions. Premature ventricular contractions may be different, with randomized evidence suggesting that they can increase in some individuals. For most healthy adults, up to about four hundred mg daily or roughly three-five eight ounce cups appear safe. But dose, preparation, blood pressure, sleep, and individual response still matter. Unfiltered coffee can raise LDL cholesterol.
Niraj Sharma:Energy drinks and concentrated caffeine are a different risk category. The EP Edge take: Don't give every patient with AF a reflex lifelong coffee ban. Ask what they drink, how much, whether it disrupts sleep or raises blood pressure, and whether symptoms are reproducible. Then personalize the advice. From coffee, let's move to wine.
Niraj Sharma:And here the evidence may be even more vulnerable to the story we want it to tell. Martinez Gonzalez and colleagues examined wine consumption within a Mediterranean dietary pattern. Their study was published in the July 2026 issue of the European Heart Journal. Why was it needed? Wine often travels alongside the Mediterranean diet.
Niraj Sharma:If wine drinkers have better outcomes, is it the wine, the diet, the social setting, or differences that are difficult to measure? The investigators used two Spanish cohorts. PREDIMED included 7,447 older adults at high cardiovascular risk. The SUN cohort included 10,554 generally younger adults over age 40. In Predimed, people with high dietary adherence who drank wine had lower cardiovascular risk than those with low adherence and no wine.
Niraj Sharma:The hazard ratio was 0.55, suggesting a forty five percent lower relative risk. That sounds impressive. But look carefully at the comparison. The two groups differed in both diet and wine consumption. When the investigators compared wine drinkers with non drinkers among those already following the diet closely, the hazard ratio moved to 0.65, the confidence interval crossed one, and the p value was 0.065.
Niraj Sharma:In plain language, the result no longer met the conventional threshold for statistical significance. The mortality signal was somewhat stronger. But there wasn't a significant interaction between wine and dietary adherence. The younger SUN cohort didn't reproduce the cardiovascular finding. Stockwell and Zhao explored these concerns in an accompanying editorial.
Niraj Sharma:It was published in the July 2026 issue of the European Heart Journal. Their central question was simple and incredibly important: who exactly is in the reference group? Here is why the reference group matters so much. A non drinker group may include lifelong abstainers and former drinkers who stopped because they became ill. If that group has higher baseline risk, moderate drinkers can look healthier simply because of the comparison.
Niraj Sharma:When moderate drinkers were compared with very light drinkers, the apparent benefit largely disappeared. The hazard ratio was 0.99 for total alcohol and 0.93 for wine. Neither was significant. So the underlying participants didn't change, but the comparison group did and that substantially changed the message. Now let's bring this back to electrophysiology.
Niraj Sharma:These studies didn't examine atrial fibrillation outcomes. We can't take a cardiovascular or mortality association and quietly convert it into evidence that wine prevents AF. Alcohol can trigger AF and even moderate intake may matter when a patient has a reproducible relationship between alcohol and arrhythmia. The EP Edge take: Encourage the Mediterranean dietary pattern. Don't prescribe wine as cardiovascular therapy.
Niraj Sharma:Or claim that it protects against AF, coffee and wine shouldn't be placed in the same bucket. Coffee evidence challenges routine prohibition in AF. Wine evidence doesn't justify recommending alcohol, and its apparent benefit depends heavily on the reference group. If you'd like the full confidence intervals, tables and references, they are available in EP Edge Journal Watch. Now let's pivot from lifestyle exposures to sudden cardiac death, where the difference between an assumed diagnosis and a proven diagnosis can completely reshape prevention.
Niraj Sharma:For decades, ischemic heart disease has dominated the way we think about sudden cardiac death. But how much of that model survives when presumed sudden deaths undergo systematic autopsy? Nakasuka and colleagues tackled that question. Their study was published in JAC in July 2026. They examined nine forty three presumed sudden deaths from the post SCD program.
Niraj Sharma:Death certificates and clinical impressions can misclassify both cause and mechanism. If prevention is built around the wrong denominator, we may target only part of the problem. Autopsy showed that three sixty of the presumed sudden deaths (or thirty eight percent ) were actually non cardiac. That left five eighty three autopsy confirmed sudden cardiac deaths. Myocardial infarction accounted for two thirty seven cases (or forty one percent That s only about one quarter of all deaths initially presumed to be sudden cardiac deaths.
Niraj Sharma:That's a major correction. Myocardial infarction remains important, but it didn't explain most presumed sudden deaths in this cohort. Among the infarction related cases, ninety five involved acute infarction with obstructive coronary disease, one hundred and nineteen involved healed infarction, and twenty three involved acute myocardial infarction with non obstructive coronary arteries MINOCA. MINOCA accounted for about ten percent of infarction related sudden deaths, and roughly one in five acute infarctions. The right coronary artery was the most common culprit, accounting for forty three percent compared with thirty six percent for the left anterior descending artery.
Niraj Sharma:Overall, eighty nine percent of infarction related sudden deaths were arrhythmic. In acute menaca, nonarrhythmic death was more common than in acute obstructive infarction (thirty five versus fifteen percent That difference was significant before adjustment, but not afterward. It's a signal needing confirmation, not a definitive conclusion. The healed infarction group was particularly sobering. Ninety seven percent of those deaths were considered arrhythmic.
Niraj Sharma:Yet among thirty seven people who'd had an echocardiogram before death, only fourteen met the conventional fraction criteria for a primary prevention defibrillator. That doesn't mean current defibrillator criteria are wrong, it means ejection fraction is an incomplete filter. Scar architecture, autonomic influences, ischemia, genetics, and other markers may identify risks that one measurement misses. Dumas and Cariou reinforce this point in an accompanying editorial. It was published in JACC or JACC in July 2026.
Niraj Sharma:The findings don't diminish ischemic heart disease. They show that sudden death is broader than our traditional model. The study came from a regional autopsy cohort. Evaluations may differ, and determining mechanism after death still requires judgment. Even so the value is substantial because the study replaces assumption with tissue level evidence.
Niraj Sharma:The EP Edge take is that prevention has to extend beyond obstructive coronary disease and a low ejection fraction. Minocca isn't automatically benign. Healed infarction can remain a rhythmic substrate above the usual device threshold. Systematic autopsy can also guide family evaluation, reveal missed disease, reshape public health priorities and improve risk markers. That brings us to the resuscitation itself.
Niraj Sharma:During an out of hospital cardiac arrest, can end tidal CO2 tell us when return of spontaneous circulation is becoming more likely? End tidal CO2 is available in real time and reflects pulmonary blood flow, but one low value can become dangerously persuasive if it is treated as a reason to stop. Nassol et al. Examined this question in a secondary analysis of the PART trial. Their study was published in Circulation in July 2026.
Niraj Sharma:They studied eleven sixty eight patients who had capnography recorded during out of hospital cardiac arrest. Overall, eighteen point two percent achieved return of spontaneous circulation. Investigators examined the trajectory, not one isolated value. Was it rising or falling? When did those patterns separate patients who regained circulation from those who didn't?
Niraj Sharma:In witnessed arrests with an initial value of 30 or less, the trajectory separated at about eight minutes. A rising trajectory was associated with roughly three times the likelihood of return of spontaneous circulation. With moderate starting values, separation appeared around twelve minutes and with high values around twenty one minutes. In unwitnessed arrests, it appeared around seven minutes. Don't memorize every time point.
Niraj Sharma:The larger message is that the starting value and clinical context determine when the trend becomes informative. Direction matters more than one snapshot. But this isn't a termination rule. Even with a low downward trajectory at eight minutes, about eight percent still achieved return of spontaneous circulation. The confidence interval was roughly four to thirteen percent.
Niraj Sharma:That's far too much possibility to declare futility from capnography alone. The EP Edge take is to use end tidal CO2 as dynamic feedback within the whole resuscitation picture. Consider the trend: compression quality, rhythm, medications and reversible causes. Don't allow one low value to end a potentially salvageable resuscitation. Validation with neurological outcomes is still needed.
Niraj Sharma:Our final theme asks a very different question. What happens when the patient is extraordinarily fit but the electrical system isn't entirely normal? The final paper focuses on Masters athletes, generally adults aged 35 or older who train well beyond standard exercise recommendations. Issue August and colleagues developed this joint European and American clinical consensus. It was published in JAAC in July 2026.
Niraj Sharma:Why was it needed? Clinicians can make two opposite mistakes: label normal athletic adaptation as disease or dismiss genuine disease because the patient looks exceptionally fit. For atrial fibrillation, the relationship with exercise appears U shaped. Moderate activity is protective, but years of high volume endurance training may increase AF risk. Among Nordic skiers, AF prevalence was approximately doubled, with some adjusted estimates two point five to four times higher.
Niraj Sharma:Potential mechanisms include atrial enlargement, autonomic change, conduction remodeling, and fibrosis. Treatment principles must be adapted to the athlete. Symptomatic athletes often favor rhythm control because rate controlled drugs may limit performance. Early pulmonary vein isolation can be reasonable after shared decision making. Anticoagulation should follow standard stroke risk assessment.
Niraj Sharma:Left atrial appendage occlusion shouldn't be offered simply to avoid anticoagulation during sport. Evidence isn't strong enough to promise that detraining will reverse AF. Bradycardia is common, but symptoms still require evaluation. Among male skiers, bradycardia and pacemaker implantation were reported nineteen and seventeen percent more often. Premature ventricular complex prevalence ranged from seven percent in ultramarathon runners to thirty four percent in older athletes.
Niraj Sharma:Burden isn't the whole story. Polymorphic, repetitive, short coupled, exercise emergent or symptomatic ectopy concerning morphology or a burden above roughly ten percent should prompt deeper evaluation. The EP Edge take is that fitness isn't immunity. Use electrocardiography, echocardiography, exercise testing, ambulatory monitoring during training, and cardiac MRI when indicated. Preserve the athlete's identity while taking genuine electrical disease seriously.
Niraj Sharma:Let's close with a quick recap. For persistent AF, pulsed field ablation produced encouraging one year rhythm control, but the available comparisons didn't prove that it was superior to thermal ablation. When patients returned for a redo procedure, reconnection after pentaspline pulsed field ablation appeared broader and more left sided. That suggests comprehensive mapping may be more useful than searching for one focal gap. The SPHER-nine reports highlighted ventricular arrhythmias and implanted device interactions during radiofrequency delivery, but without a denominator they can't provide incidents.
Niraj Sharma:SmartBeat showed that smartphone rhythm monitoring can move critical information forward in time, preventing about one same day cardioversion cancellation for every six patients monitored. The caffeine statement challenges routine coffee prohibition in AF while reminding us to consider ventricular ectopy, sleep, blood pressure, energy drinks, and individual response. The wine analyses support the Mediterranean diet, not a prescription for alcohol. The apparent benefit weakened when the reference group changed and the studies didn't test an AF benefit. The autopsy study showed that myocardial infarction accounted for forty one percent of confirmed sudden cardiac deaths, and that ejection fraction alone misses substantial arrhythmic risk.
Niraj Sharma:End tidal carbon dioxide trajectories can inform resuscitation, but no single value or downward trend should become a stand alone reason to stop. Finally, in master's athletes, high fitness and important arrhythmia can coexist, respect athletic physiology, investigate high risk features, and make decisions with the athlete. Across these studies, the first number is rarely the whole answer. The comparison group, denominator, monitoring strategy, and patient in front of us determine what the evidence really means. If you'd like to explore the full statistics, confidence intervals, limitations, tables, and clinical commentary, You will find them in EP Edge Journal Watch.
Niraj Sharma:All references and graphics are available in the LinkedIn newsletter, EP Edge Journal Watch, as well as on Substack at epedge. Substack . com. Questions, suggestions or concerns can be sent to epedge. Castgmail . com. Thank you again for listening and thank you for being part of the growing EP Edge community.
Niraj Sharma:I'm Doctor. Sharma, take care, bye for now and I'll see you in the next episode.