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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 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 everyone and welcome to EP Edge Journal Watch Issue 34 for August 2026. I'm Doctor. Sharma and I'm very glad you're here. Before we get into the studies, I want to say thank you. Many of you have written with suggestions, challenged an interpretation, recommended a paper, or told me what would make the newsletter and podcast more useful.
Niraj Sharma:I genuinely appreciate that. EP Edge is better when it feels like a conversation with a thoughtful community rather than a lecture moving in only one direction. This is an interesting issue because it arrives during a quieter period for major electrophysiology trials. Over the last three or four issues, we haven't had one enormous randomized trial that changes practice overnight. But quieter doesn't mean unimportant.
Niraj Sharma:Smaller randomized trials, prospective cohorts, and carefully designed observational studies can reveal a safety signal, challenge an assumption, or show us exactly what the next larger trial needs to answer. So today we are going to follow nine clinical stories. We will ask whether the pathway of an ICD shock changes myocardial injury, why migraine can appear after PFA, whether mechanical CPR improves survival when an entire EMS agency adopts it, and whether hemolysis differs among PFA platforms. We will look at fine renone and sudden death, the LOSE AF weight loss trial, radiation safety during pregnancy, skin thickness over cardiac devices and two commonly used treatments for POTS. For every study, I'll give you the clinical question, how the investigators try to answer it, what the statistics really mean, and the EP Edge take for practice.
Niraj Sharma:Let's begin with what's coming for EP Edge itself. September 2026 is the planned launch of epedge.org, with the EP Edge app expected around the same time. This isn't simply a new address for the newsletter. The goal is a connected electrophysiology knowledge platform built around three ideas: knowledge, access, and humanity. Knowledge means moving beyond the abstract.
Niraj Sharma:EP Edge analytics will examine how trials were designed, what the statistics actually support, where bias can enter and how the results should or should not change a clinical decision. EP Edge Academy will build structured learning from foundational concepts to advanced electrophysiology. There will also be CME and MOC pathways, along with EP Edge Rx, which is designed to turn therapeutics into practical patient centered information. Access means putting the full newsletter archive, trial analyses, educational material, and clinical tools in one place. Once the site is live, the complete newsletters will live on epedge.org.
Niraj Sharma:LinkedIn and Substack will continue with abridged editions, so readers can still engage in the places they already use. And humanity means remembering why all of this exists. Evidence matters because people matter: the patient living with uncertainty, the trainee looking for a clear explanation, the clinician making a difficult decision, and the allied professional keeping the entire system moving. One more important preview, next week's episode will be a special collaborative issue with the Heart Rhythm Society. It is a must listen episode so please watch for it.
Niraj Sharma:Now let's move into the first study. It asks a deceptively simple question: When an ICD delivers a shock, does the route that current takes through the body change the amount of myocardial injury? The first paper was led by Takahide Kadosaka and first published in June 2026 in the Journal of Cardiovascular Electrophysiology. Here's why this study was needed: We know an ICD shock can save a life by terminating ventricular fibrillation, but a life saving intervention isn't necessarily biologically neutral. Patients who receive shocks often have worse outcomes, yet that association is difficult to interpret.
Niraj Sharma:Is the shock damaging the myocardium? Is the rise in troponin caused by placing a transvenous lead? Or are sicker patients simply more likely to need shocks? Kadasaka et al. Studied seventy four patients receiving their first device.
Niraj Sharma:They compared transvenous ICD implantation with defibrillation testing, transvenous devices without testing, and subcutaneous ICD implantation with testing. Troponin was measured before implantation and again afterward. Within the transvenous group, the investigators also asked whether more total shock energy tracked with a larger biomarker rise. The main result was not just that troponin increased, transvenous lead placement itself produced a signal, and the increase was greatest when implantation included transvenous defibrillation testing. More importantly, total transvenous shock energy remained associated with the change in log troponin.
Niraj Sharma:The regression beta was 0.021 per joule, with a p value of 0.001. The subcutaneous group did not show the same significant troponin rise. What does that statistic mean? The dose response relationship strengthens the biological argument. More transvenous energy tracked with more acute biomarker release.
Niraj Sharma:But the outcome is on a logarithmic troponin scale, so the beta isn't an intuitive amount of clinical damage. And because the groups weren't randomized, differences in age, ventricular function, lead trauma and clinical status remain important. The EP Edge Take is practical. Don't avoid a necessary life saving shock. Do avoid unnecessary shocks.
Niraj Sharma:Program thoughtfully and perform defibrillation testing for a clear clinical reason, particularly when myocardial reserve is limited. This study suggests the shock vector matters, but it doesn't prove a long term outcome advantage for the subcutaneous system. For the full regression details and graphics, see the EP Edge Journal Watch Newsletter. From shock injury, let's move to a symptom that can be frightening after a left atrial procedure: a new migraine, sometimes with visual aura. This multicenter analysis was led by Sanghamitra Mohanty and first published in June 2026 in the Journal of Cardiovascular Electrophysiology.
Niraj Sharma:The study was needed because migraine after transseptal procedures is uncommon but memorable. A transseptal puncture creates a temporary atrial communication, and investigators have wondered whether microemboli, platelet products, vasoactive mediators, or the ablation process itself might trigger migraine. With PFA expanding rapidly, clinicians needed a credible estimate of how often this occurs and whether one platform appeared different from another. The investigators prospectively followed more than 2,000 PFA procedures performed with three contemporary systems. They looked for newly diagnosed migraine or a meaningful worsening of pre existing migraine, and they examined the timing, duration, and possible predictors.
Niraj Sharma:The central message is reassuring: new migraine was uncommon, occurring after about one point four percent of procedures. It generally appeared several days later and was usually short lived. No stroke or transient ischemic attack was reported among the affected patients, although only two underwent brain MRI, so we shouldn't overread that reassurance. Statistically, this is a rare event study. The platform estimates had wide overlapping confidence intervals, so the data do not establish a safer or riskier PFA system.
Niraj Sharma:Body mass index emerged as a predictor, with an odds ratio of about 1.4, but the confidence interval started at 1.002, almost touching the null. With only 31 events and several variables in the model, that association is fragile and needs confirmation. The EP Edge take is to counsel patients that post PFA migraine is uncommon and often transient, while keeping neurologic vigilance high. A focal deficit, unusual aura, or severe new headache must never be dismissed as just migraine. We also should not declare a platform winner from these data.
Niraj Sharma:The newsletter has the platform specific confidence intervals and a fuller discussion of what future imaging studies should do. Now let's leave the EP lab and go into the pre hospital resuscitation system. The mechanical CPR study was led by Paul S. Chan and published in August 2026 in Circulation. The clinical appeal of mechanical CPR is obvious: a device can deliver consistent compressions, reduce rescuer fatigue, and free the team to manage defibrillation, airway, medications, transport and reversible causes.
Niraj Sharma:But the important question isn't whether the device can compress the chest consistently. It's whether introducing the device into routine care helps more people leave the hospital alive with meaningful neurologic function. Patient level comparisons are badly distorted by resuscitation time bias. Someone who regains circulation quickly stays in the manual group, while someone with prolonged refractory arrest is more likely to receive the device. Chan and colleagues therefore moved the question to the agency level.
Niraj Sharma:Using the CARES registry, they studied more than eighty three thousand out of hospital arrests. They compared agencies that never adopted mechanical CPR with agencies that introduced it, and used an interrupted time series model to ask two questions: Did survival jump immediately? And did the survival trend improve afterward? Neither happened. Neurologically favorable survival did not improve after adoption, and neither did survival to discharge.
Niraj Sharma:The adjusted odds ratio for an immediate change was zero point nine four, with a confidence interval from 0.80 to 1.11. The annual slope estimate was close to one as well. In plain language, there was no detectable survival jump and no better trajectory. The confidence intervals matter. They argue strongly against a large routine benefit, but they still allow a modest benefit or modest harm.
Niraj Sharma:And because this was an observational implementation study, it evaluates what happened when agencies adopted a program, not whether flawless device deployment helps a carefully selected individual. The EP Edge take is that technology cannot rescue a weak system by standardizing only one component of resuscitation. Mechanical CPR may still have value during prolonged transport, unsafe manual compression, refractory arrest pathways, or extracorporeal CPR workflows. Those are the settings that need focused trials measuring deployment delay and protocol fidelity. Staying with technology, let's return to PFA.
Niraj Sharma:But this time we'll look beyond the lesion and into the bloodstream. This study was led by Matteo Rocchetti and published online in July 2026 in Europace. The reason it matters is that PFA is myocardially selective but it is not blood selective. High voltage applications occur inside a blood filled chamber and red cells can be electroporated. The important unanswered question was whether hemolysis is simply a class effect of all PFA or whether catheter geometry and workflow create different biological footprints.
Niraj Sharma:The investigators prospectively enrolled two thirty nine patients treated with a pentaspline catheter, a balloon in basket catheter, or a lattice tip catheter. They measured markers of hemolysis, kidney function, and myocardial injury before the procedure and the following morning. Because the laboratory values weren't normally distributed, they used nonparametric tests, including Wilcoxon testing within groups and Kruskal Wallis testing across platforms, with correction for multiple comparisons. The main finding was platform specific. The strongest fall in haptoglobin, the clearest biochemical sign of hemolysis, occurred with the pentaspline workflow.
Niraj Sharma:Five mild stage one acute kidney injury events occurred all in that group. The reassuring part is that the renal changes were transient, and nobody required dialysis or nephrology consultation. The statistical signal for the kidney event comparison reached a p value of 0.020. But association is not causation here. The platforms weren't randomized, workflows differed, lesion sets differed, and the number of applications and fluid strategies could matter.
Niraj Sharma:The multiplicity correction helps reduce false positive pairwise findings, but it cannot remove confounding. The EP Edge take is that we should stop borrowing a safety profile from one PFA system and applying it automatically to another. For routine pulmonary vein isolation in a patient with good renal reserve, the clinical consequences appeared limited. In chronic kidney disease, extensive lesion sets, dark urine or high application counts, be more deliberate. Avoid unnecessary applications, hydrate appropriately and consider post procedure creatinine and urine assessment.
Niraj Sharma:Our next study shifts from procedural safety to sudden death across the cardio kidney metabolic spectrum. The fine heart analysis was led by Alberto Foy and published in August 2026 in the Journal of the American College of Cardiology. Why was it needed? Phenarinone already has evidence for improving cardiorenal outcomes, but sudden death is often buried inside larger cardiovascular composite. Investigators wanted to know whether phenyrinone might influence this specific mode of death across patients with diabetes, kidney disease, and heart failure.
Niraj Sharma:They pooled participant level data from three randomized, placebo controlled trials, creating a population of nearly nineteen thousand patients. Deaths were adjudicated by blinded committees. The analysis used trial and region stratified COX models, and a fine gray competing risk analysis accounted for the fact that a patient who dies from another cause can no longer experience sudden death. Sudden death made up a large portion of cardiovascular mortality. Phenerinone was associated with a lower risk than placebo, with a hazard ratio of 0.81.
Niraj Sharma:That's a relative reduction of about nineteen percent. The confidence interval ran from 0.67 to 0.98, and the p value was 0.034. The competing risk result was essentially the same. This is credible because the underlying treatment allocation was randomized and the event adjudication was blinded, but the statistical margin was modest, the confidence interval barely excluded one, and the absolute event reduction was small. The estimated number needed to treat was around two sixteen.
Niraj Sharma:Also, most sudden deaths were not captured on a rhythm monitor, so we cannot assume the mechanism was prevention of ventricular arrhythmia. The EP Edge take is that this is an intriguing extension of a medication with established cardiorenal benefit, not a new antiarrhythmic indication. It raises a mechanistic question: is the signal mediated through potassium stability, reduced fibrosis, fewer heart failure events, less arrhythmia, or several pathways together? From finerenone, let's move to a treatment we already recommend broadly: weight management in atrial fibrillation. The LOSE AF trial was led by Matteo Sklafani, published online in May 2026 in JAMA and later included in the July print issue.
Niraj Sharma:The study asked an important and uncomfortable question. Obesity clearly increases the risk of developing AF, and weight loss is part of good cardiovascular care. But once an older patient has persistent AF and an established atrial substrate, can weight loss by itself reverse symptoms and rhythm burden? And can it be done without worsening frailty? The investigators randomized one hundred and eighteen adults, ages 60 to 85, who had persistent AF, a body mass index of at least twenty seven, and planned cardioversion.
Niraj Sharma:One group received an eight month low calorie diet with behavioral support. The other received usual care. The original recurrence focused trial was disrupted by the pandemic, and the primary endpoint was amended to an AF symptom score. The intervention worked for weight loss. The between group difference was nearly seven kilograms, and the intervention group lost close to 10% of body weight, but the primary AF outcome was negative.
Niraj Sharma:Symptoms did not improve significantly, AF burden was not lower, cardiac remodeling did not meaningfully change, and later cardioversion or ablation remained similar. The adjusted symptom difference was less than one point, with a confidence interval from -3.3 to plus 1.4 and a p value of 0.43. That confidence interval is informative. It did not reach the pre specified four point threshold for a clinically important benefit. So this isn't simply a study that missed significance by a little.
Niraj Sharma:It tells us that a large symptom effect is unlikely in this population. At the same time, the trial was too small for the original recurrence question and many secondary outcomes. The EP Edge take is not to abandon weight management. Weight loss remains important for blood pressure, diabetes, sleep apnea, fitness, and overall cardiovascular health. But don't promise that weight loss alone will reverse persistent AF.
Niraj Sharma:The benefit may be greater earlier in the disease course, as part of comprehensive risk factor management, or when paired with rhythm control therapy. The newsletter explains the amended endpoint, ANCOVA analysis and missing data assumptions in greater detail. Now we come to a study that is as much about access and career equity as it is about radiation. This research letter was led by Johanna Muller Leise and published in August 2026 in Circulation. In invasive cardiology and electrophysiology, pregnancy can become a career defining event.
Niraj Sharma:Without real world exposure data, physicians may stop procedural work or training because the risk feels unknowable. The investigators wanted to measure what actually reaches uterine level beneath contemporary protective equipment. They simulated two separate forty week pregnancy periods in a modern EP laboratory. A continuously active dosimeter was worn beneath a 0.35 millimeters two piece lead apron at uterine level. A second dosimeter stayed in the control room to measure background.
Niraj Sharma:Across the two periods, the operator participated in six eighty eight procedures, including ablations and device cases using modern shielding, low dose fluoroscopy, and mapping focused workflows. After background subtraction, the mean additional uterine level exposure was 0.037 mSieverts. That is a very small exposure relative to the regulatory limits discussed in the paper. The weekly difference generated a p value of 0.016, but this is a perfect example of why statistical significance is not the same as clinical magnitude. Repeated measurements can make a tiny difference statistically detectable.
Niraj Sharma:The decision relevant result is the size of the cumulative additional dose. Background subtraction was crucial. Most of what the underapron dosimeter recorded was also present in the control room. Without that comparison, the procedural contribution would have looked far larger. The EP Edge take is that a modern, disciplined EP laboratory can support continued procedural participation with very low additional exposure.
Niraj Sharma:The transferable intervention is the system: low dose settings, overhead and table shielding, mapping, procedural discipline, and continuous individual monitoring. These results support informed choice rather than automatic exclusion. They do not eliminate the need for local dosimetry because equipment, case mix, operator position, and patient size vary. The full measurement table and graphic are available in the newsletter. The next paper begins with something clinicians can see and feel at the bedside: thinning skin over a pacemaker or defibrillator.
Niraj Sharma:The study was led by Shogo Yonehera and first published in March 2026 in Pacing and Clinical Electrophysiology. Thin skin over a device is usually treated as a local pocket concern because it may increase visibility, discomfort, erosion or infection. But the investigators asked a broader question: Could skin thickness also reflect systemic reserve including nutrition, anemia, kidney disease, heart failure, malignancy or frailty. Ninety six Japanese patients with existing cardiac devices underwent standardized ultrasound measurements at five points over the generator. Thin skin was defined as 3.3 millimeters or less based on prior work.
Niraj Sharma:Patients were followed for clinical outcomes and thirty four returned for repeat ultrasound, allowing the investigators to examine change over time. Skin thickness declined not only over the device but also on the opposite side, supporting the idea that this may be a systemic signal rather than simply pressure from the generator. Mortality was higher in the thin skin group. After adjustment, skin remained associated with mortality with a hazard ratio of about two point four two. But here's the statistical caution: the confidence interval extended from just above one to nearly 5.8, and the p value was 0.046.
Niraj Sharma:That's wide, borderline, and based on only twenty seven deaths. The investigators used stepwise variable selection, which can overfit a small dataset and make an association look more independent than it really is. Thin skin may be a marker of illness rather than a direct cause of mortality. The EP Edge take is to use the finding as a clinical prompt, not a prognostic score. If the device pocket looks thin, consider ultrasound and assess anemia, nutrition, kidney function, heart failure, malignancy, frailty and erosion risk but don't tell a patient that a 3.3 determines prognosis.
Niraj Sharma:The threshold needs prospective external validation. The newsletter includes the survival data and a fuller discussion of overfitting. Our final trial focuses on POTS, where treatment often requires careful individualization. This randomized crossover trial was led by Jaden Uppol and published in July 2026 in the Journal of the American College of Cardiology. Patients with POTS can have disabling tachycardia, cognitive symptoms, fatigue and poor upright tolerance yet no medication is specifically approved for the syndrome.
Niraj Sharma:Ivobradine and low dose propranolol are both used off label, but they slow the heart differently and had not been compared directly in a randomized trial. Twenty eight women with POTS completed three four week treatment periods in random order: ivabradine, propranolol, and placebo, with a seven day washout between phases. Because every participant received every treatment, each person served as her own control. Each phase ended with a head up tilt test, and the primary outcome captured the increase from baseline to peak upright heart rate. Both active drugs reduced orthostatic tachycardia compared with placebo.
Niraj Sharma:Ivobradine also produced a somewhat larger rise in upright systolic pressure than propranolol. Patient preference was split rather than unanimous, which may be one of the most clinically useful findings. The paired comparisons with placebo had p values below 0.001, showing a clear within person heart rate effect. But no significant difference between the active drugs does not prove that they are equivalent. With only 28 participants, the trial could easily miss a clinically meaningful difference, and because many secondary hemodynamic, symptom, cognitive and preference outcomes were tested, some positive secondary findings may occur by chance.
Niraj Sharma:The EP Edge take is that both drugs are reasonable options. Ivabradine may be attractive when preserving or augmenting upright blood pressure matters. Propranolol may suit a more adrenergic phenotype or a patient who experiences broader symptomatic benefit. Start with the patient's physiology and goals, measure the response, and revisit the choice rather than selecting therapy from heart rate alone. The complete paired data and limitations are in the EP Edge Journal Watch newsletter.
Niraj Sharma:The defibrillator study suggests that transvenous shock energy leaves a measurable acute troponin footprint, while the subcutaneous pathway did not show the same signal. The migraine study tells us that new migraine after PFA is uncommon and often brief, but neurologic symptoms still deserve serious evaluation. Routine agency wide adoption of mechanical CPR did not improve survival, although selective use may still make sense in specific resuscitation pathways. PFA hemolysis and kidney effects differed by platform and workflow, reminding us not to treat every catheter as biologically identical. Finerenone showed a modest reduction in sudden death across the fine heart population, but this is an extension of cardiorenal benefit, not a new antiarrhythmic indication.
Niraj Sharma:LOSE AF achieved meaningful weight loss without improving established persistent AF, so weight management remains essential without being oversold as rhythm reversal. Modern protection produced very low additional uterus level radiation in one contemporary EP laboratory, supporting informed choice and individual monitoring during pregnancy. Thin skin over a cardiac device may identify systemic vulnerability, but it is a prompt for broader assessment, not a standalone mortality score, and in POTS, both evobradine and low dose propranolol reduced orthostatic tachycardia, with physiology and patient preference guiding the choice. If you want the complete methods, statistics, references, graphics, they are available in the LinkedIn newsletter, EP Edge Journal Watch, and on Substack at epedge. Substack . com.
Niraj Sharma:Questions, suggestions, or concerns can be emailed to epedge. Cast@gmail . com. Please remember that next week's special collaborative episode with the Heart Rhythm Society is a must listen. And in early September watch for epedge.org and the EP Edge app, bringing the newsletter archive and practical electrophysiology education into one connected platform. Thank you again for listening and thank you for helping shape EP Edge with your questions and suggestions.
Niraj Sharma:I'm Doctor. Sharma, I'll see you in the next collaborative episode with HRS. Take care and bye for now.