Niraj Sharma: Welcome back to EP Edge Journal Watch. I'm Doctor. Sharma and today we are doing something a little different. This isn't just a tour through new papers, this is an episode built around one core question: What does success actually mean after atrial fibrillation ablation At one year, four years, and even twenty years. And here is the uncomfortable part.
Sometimes the success rate you hear is not biology, it is monitoring, its endpoints, and its definitions. Then we pivot to two practical problems you will actually face in the lab: ablation in patients with implanted devices and pacing induced cardiomyopathy in the leadless era. Here is the roadmap: First, ADVENT long term outcomes, the ADVENT LTO extension. This matters because ADVENT has been the most comprehensive, two arm, well monitored comparison of pulsed field ablation against thermal energy in paroxysmal AF. Second, a twenty year follow-up cohort from Hamburg that tells you what durability looks like when you zoom all the way out.
Third, a JACClinical EP paper that basically argues we're comparing trial results the way people compare car mileage stickers without checking how the test was run, and then two reality checks the MAWD signals in ablation plus cardiac implantable devices patients and the pacing induced cardiomyopathy data comparing leadless versus transvenous RV pacing. Alright, let's start with the headliner. Study one: ADVENT LTO If you've heard any criticism of pulsed field ablation, it's usually this: Sure it's safe, but will it last? ADVENT LTO is the first randomized platform that directly addresses durability over roughly four years and I want to frame the headline carefully. The headline is not PFA wins by a mile.
The headline is The effect does not collapse over time and the downstream events that patients actually feel trend in the right direction. Let's get the basics straight. This was an observational long term extension of the randomized ADVENT trial. So we're no longer in the clean world of perfect randomized follow-up. The extension enrolled three sixty four patients, one hundred and eighty three in the pulsed field group, one hundred and eighty one in the thermal group.
Follow-up was about thirteen thirty two days on average (think of it as roughly three point six years after the index procedure extending to about four years total). Now before we even touch the outcomes, we have to talk about the silent driver of success rates: Monitoring. In the original pivotal year of ADVENT, the monitoring was intensive, weekly transtelephonic monitoring from months three through 12, ECGs at three, six, and twelve months, and seventy two hour Holters at six and twelve months. In ADVENT LTO, the extension monitoring was closer to real world, retrospective chart review plus independent core lab review, and then a prospective seven day Holter at four years but only in a subset: 138 in the pulse field group, 119 in the thermal group. Why does this matter?
Because if you don't look as hard, you find less AF and your success rate looks better. So in long term extensions, you should interpret success as clinical success more than no thirty second episodes ever. Okay, outcomes: The primary endpoint was four year treatment success seventy two point eight percent with pulse field, sixty four point one percent with thermal, p value 0.12, translation: that's about a nine percent absolute difference clinically suggestive but statistically not definitive. You can't stand on a podium and claim superiority based on the primary endpoint alone. But the more interesting signals are the downstream events.
Freedom from hospital based arrhythmia intervention was eighty five point six percent with pulsed field versus seventy eight point six percent with thermal. The hazard ratio was 0.64 with a confidence interval crossing one. So again a trend, not proof. Now the cleanest hard signal in this dataset is repeat ablation, ten point four percent with pulse field versus seventeen point seven percent with thermal. P value 0.04.
That is not marketing. That is a tangible difference patients feel and health systems feel. And if you do a crude back of the envelope, that's roughly a number needed to treat around fourteen to prevent one redo over about four years. Context matters, but direction matters too. Progression to persistent AF was low in both groups: two point six percent with pulse field versus four point six percent with thermal.
Hazard ratio: 0.55 but a very wide confidence interval. That's basically telling you event rates are low and the study is underpowered for progression. So what do I take to rounds from ADVENT LTO? One. The durability argument against pulsed field gets weaker, not stronger as time passes.
It doesn't look like the lesions fade out early. Two. Even if the primary endpoint is statistically neutral, redo ablation and hospital based interventions matter. Those are the outcomes that translate into quality of life and resource use. And three.
Always ask how hard did they look? Because the success rate is inseparable from the surveillance plan. Quick clinical translation before we move on. If you are in clinic and a patient asks Doc, does POLST field last? My answer is we now have randomized comparative data out to about four years and the durability signal is reassuring, not because every endpoint is statistically superior, but because the curve doesn't fall apart and fewer people need to come back for a redo.
And then I add the honest qualifier: long term outcomes depend on more than the energy source. It depends on atrial biology, risk factor control, and whether we are measuring no recurrence at all versus a life that feels normal again. That theme is about to show up again in a big way. Now let's zoom out, because four years feels long until you look at 20. Study two: twenty year pulmonary vein isolation outcomes.
This is the Hamburg cohort from the early 2000s. Symptomatic drug refractory paroxysmal AF treated in 2003 and 2004 with RF circumferential PVI and PV isolation was confirmed with the double lasso technique. N was 154. Median follow-up was about nineteen point three years, and recurrence was defined as symptomatic or asymptomatic atrial arrhythmias longer than thirty seconds, documented by ECG, Holter, wearables, or devices, no predefined blanking period and death was handled as a competing event. Here's the part I want you to feel in your gut because it changes how you counsel patients.
Median recurrence free survival after the first ablation was about four years and by around nineteen point five years AF after the first procedure was about twenty six percent. So if you are thinking one procedure, lifetime cure, this paper politely walks you out of the room. Now you might say, okay that's single procedure, what about the real world strategy, multiple procedures plus meds? Multiple procedural success at about nineteen point five years was still around twenty five percent. The cohort averaged about two ablations plus or minus one, and about a quarter were still on antiarrhythmic drugs at last follow-up more than half underwent at least one re ablation.
Fifty three percent had redo work, with a distribution that included multiple procedures in a minority. An atrial tachycardia ablation occurred in about eleven percent. One nuance I love in this dataset is the timing of redo work. In years ten-twenty, only 11 re ablation procedures were performed so the redo burden didn't explode late. Most of the repeat work happened earlier.
Which is exactly how many of us experience it clinically. It's not that nothing happens after ten years, it's that late events are a smaller phenotype and the mechanisms often look different. But here's the mechanistic pearl. Very late recurrences meaning after ten years occurred in about eight percent overall. And specifically, more than ten years after the index PVY, it was about three percent.
So late recurrences are real, but they're not an epidemic. Now in patients who underwent redo after a very late recurrence, their redo mapping data are fascinating. PVI durability was eighty three percent, 30 of 36 veins still isolated, and all pulmonary veins remained isolated in about two thirds of those patients. So what's the implication? If someone shows up ten to twenty years later with AF or atrial tachycardia, the pulmonary veins are often still isolated.
That pushes you toward non PV triggers, progressive atrial cardiomyopathy or organized atrial tachycardia mechanisms. Not reflexively, the lines opened. And this is where I think the field sometimes over focuses on the energy source. Even if pulsed field gives us better pulmonary vein durability, and it probably will, the twenty year ceiling may still be atrial cardiomyopathy. Blood pressure, obesity, sleep apnea, alcohol, metabolic health, endurance extremes, aging those variables keep pushing the atrium in the wrong direction for decades.
So the future durability conversation is likely a combined conversation: better lesion sets plus better upstream therapy. Now the anticoagulation section always triggers questions, so let's handle it responsibly. In this cohort, forty eight percent discontinued oral anticoagulation during follow-up. Among those off anticoagulation, seventy three percent were in stable sinus rhythm at last follow-up, but the median CHASVA score was still two. There were two strokes off anticoagulation, both in higher risk patients and overall thromboembolic events were seven across the cohort over two decades, major bleeding was rare, but there was one fatal major bleed, so yes, it's an interesting signal.
No, this does not justify stopping anticoagulation purely because the ablation worked. So what's the clinical message from twenty years? One. Ablation is not a one and done lifetime cure. Two.
Very late recurrence may not be PV reconnection, so don't oversimplify the mechanism. And three. The ceiling on long horizon rhythm control may be less about lesion technology and more about atrial biology, aging, and upstream risk factors. Okay, now we're ready for the paper that ties these two studies together. Study three: Defining success after AF ablation.
This JAC clinical EP paper is essentially a reality check on trial design. It argues that AF ablation trials often look in conflict because they are not measuring success the same way, and in the PFA era those differences get amplified. They focus on three design choices that drive most of the confusion: one. How intensely you monitor for recurrence two. What you call recurrence, usually the thirty second rule and three.
The blanking period, whether it's three months, two months, or shorter. Let's start with monitoring intensity because this is the quiet source of misleading comparisons. Low intensity monitoring misses asymptomatic AF and reliance on patient reporting can overestimate success by 20 or more. High intensity monitoring, especially continuous monitoring, detects more AF. It lowers the apparent success rate, even if patients feel dramatically better.
They discuss implantable monitors as a gold standard for detection and burden assessment, but adoption is limited by practical barriers. So the question becomes if you are not doing continuous monitoring, what is enough intermittent monitoring? They cite strategies like four seven day monitors every three months or two fourteen day monitors every six months. Either way, you're sampling about 28 per year. One of the most practical recommendations in the paper is this idea of dual reporting: report outcomes under the trial's actual monitoring protocol, but also report outcomes under a standardized monitoring framework so trials become comparable.
EP Edge Translation If two trials used different monitoring intensity, do not rank technologies by the headline success rates. First ask how hard did they look? Now the thirty second rule. Most trials define failure as any atrial arrhythmia recurrence lasting thirty seconds or longer after the blanking period. The paper critiques this as a convenient binary endpoint that doesn't map well to clinical meaning.
A patient can be labeled a failure for a short episode while experiencing a huge quality of life improvement. And a patient can be labeled a success while meaningful burden persists, especially if monitoring is light. That brings us to the metric that often matches what patients actually experience: AF burden. They highlight that burden captures how much AF exists, not just whether a stopwatch crossed thirty seconds. Two classic examples make the point.
In Discern freedom from thirty second recurrence was forty six percent, yet AF burden decreased eighty six percent, from about two hours per day down to about eighteen minutes per day. In circa dose, with continuous monitoring, freedom from thirty second recurrence was fifty percent, yet AF burden dropped more than ninety nine percent after ablation. This is why a binary endpoint can call the trial mediocre while the patient experiences a win. They also make an underappreciated point about burden thresholds. With non invasive monitoring, the burden threshold associated with quality of life impairment and healthcare use has been closer to ten percent, but with continuous devices the threshold can be closer to zero point one percent.
Let that sink in. Ten percent burden is about two point five hours of AF every day. 0.1 is about one point five minutes per day. So if you change the monitoring method, you change what meaningful burden looks like. That's why burden is powerful but also why it demands context.
Finally, the blanking period. Historically, it's been three months because early arrhythmias can be transient. But the paper notes that later blanking period recurrences predict late recurrence, leading to recommendations like two months for thermal ablation. For PFA, they argue the injury profile is different, less inflammation and less chronic fibrosis, and in a multicenter series, recurrence in the second or third month after PFA was strongly associated with late recurrence, so they suggest one month might be an appropriate blanking period for PFA. But, and this is important, they also emphasize the need for prospective validation.
Let me give you the EP EDGE critical appraisal version you can use on rounds. When someone quotes an ablation success rate, ask four clarifying questions: one. What was the monitoring intensity? Two. What was the endpoint threshold?
Was failure thirty seconds? Three. What blanking period did they use and how did they handle events inside blanking? And four. Did they report burden and with what monitoring?
Or did they only report time to first recurrence? If those aren't aligned, comparing technologies based on headline efficacy is closer to marketing than science. Alright, now for the first reality check that changes your workflow tomorrow morning. Study four: Ablation plus Implanted Devices This paper is a workflow paper disguised as a database analysis. They use the FDA MOD database plus a literature synthesis from twenty-twenty twenty five.
They report four thirty three adverse events in CIED patients during or after ablation. And the point is not incidence because MOD has no denominator. The point is pattern recognition. Here are the patterns matter in 2026. Ablation catheter or energy was implicated in ninety seven percent of reported events.
Most reports involved radiofrequency, about eighty nine percent, and pulse field was about eight percent. Mechanical interactions were common with lead dislodgement as a major component. Now the new failure mode signal. Pulse field accounted for all confirmed generator failures in this dataset (six cases), and lattice tip RF near biotronic defibrillator leads was linked with VF induction in the majority of RF related VF reports (fourteen out of fifteen). That is a very specific pattern and when MAUD shows you a specific pattern, you should update your mental checklists.
They also provide a supplemental categorization that is useful as long as you remember its distributions not incidents. Lead dislodgement was thirty three percent of RF reports versus three percent of pulse field reports. Resets were five percent with RF versus twenty nine percent with pulse field, and device damage was zero percent with RF versus eighteen percent with pulse field. Again, are report distributions, not denominators, but they highlight where vigilance should be concentrated. The unsettling message is this: threshold rises and device issues can occur even when ablation sites are remote from the lead tip.
So our simplistic just stay away from the lead tip heuristic is incomplete. Here are the actionable workflow implications: Prefer programming changes over magnet use when feasible, because magnet effects vary by manufacturer and can be unreliable in long cases. In pacer dependent patients, consider asynchronous pacing with higher output during ablation, while recognizing it doesn't prevent every failure mode. Be specifically cautious with lattice tip RF near biotronic ICD shock coils and pulse field in proximity to ICD leads or generators, And if interrogation fails post ablation, troubleshoot the mapping system off before committing to generator replacement and involve the manufacturer early. My practical EP checklist sounds boring, but it prevents disasters.
Before you start, get a true baseline interrogation and save it. Decide in advance whether you are using magnet or reprogramming and document why. For ICDs confirm tachytherapies are appropriately managed and make sure external defibrillation is ready. For pacer dependent patients think about asynchronous pacing with a safety margin on output. During the case minimize catheter contact with leads but don't let that be your only plan.
And after the case insist on a full interrogation thresholds, sensing, lead impedances, battery status and a printout that lives in the chart. That's how you turn a scary database signal into a safe repeatable workflow. Okay second reality check. Pacing induced cardiomyopathy in the leadless era. Study five This is a TriNetX federated EHR analysis of de novo leadless ventricular pacemakers compared with transvenous ventricular pacemakers.
They looked at implants between January 2016 and January 2023. They excluded prior heart failure (baseline ejection fraction under 50% ), prior devices at index admission. The primary outcome was pacing induced cardiomyopathy or EF declined to under fifty percent after excluding other etiologies. They did one to one propensity matching and the matched cohorts were large: two thousand five hundred and ninety four leadless and two thousand five hundred and ninety four transvenous. Here is the key result: PICM incidence was seven point six percent with leadless and eight point six percent with transvenous, not statistically different.
And in the classic high burden situations, complete heart block or AV node ablation, it was basically identical, ten point three percent versus ten point four percent. So the physiological lesson is straightforward. PICM is driven by RV activation physiology, not by whether there is a lead in the pocket. But here is the subtle management signal that matters. CRT upgrades were less frequent in leadless recipients compared with transvenous recipients, and the likely explanation is not physiology.
It is practical barriers, patient selection, infection risk, vascular access, reluctance to add a second system, and evolving comfort with extraction strategies. So the implant counseling takeaway is this: leadless may simplify early infection and lead complications, but it does not PICM proof pacing if the pretest probability of needing CRT or conduction system pacing later is non trivial. That should be explicit at implant time. Alright, let's close this out by tying the entire episode together. Closing and takeaways: If you only remember five things from this episode, make them these: one.
ADVENT LTO shows that pulsed field ablation durability does not wash out over time and the clearest hard signal is fewer redo ablations versus thermal energy over about four years. Two. The twenty year HAMBR cohort reminds you that AF is a progressive atrial disease and long term durability is not a single curve, it's a lifetime biology problem. Three. Very late recurrence often occurs with pulmonary veins still isolated, which should shift your mechanism thinking toward non PV triggers and atrial cardiomyopathy, not reflexive PV reconnection.
Number four, when someone quotes a success rate, ask the four questions: monitoring intensity, endpoint threshold, blanking period, and burden. And number five, the real world safety signals matter. MOD can't tell you incidents but it can tell you new failure modes like generator failures reported with pulsed field and VF patterns with specific RF platforms near specific ICD leads and leadless ventricular pacing does not reduce PICM risk compared with transvenous RV pacing, so physiology still wins. As always, all details, graphics, and references are available on Substack at epedge.substack.com and also on the linkedin newsletter EP Edge Journal Watch. Thanks for listening.
Until next time stay sharp, stay curious and take care of yourselves as well as your patients.