Is the Field of Electrophysiology Stuck? Three 'Hot' Topics Reviewed

John M. Mandrola, MD


June 01, 2023

I went to the Heart Rhythm Society (HRS) meeting in New Orleans as both an electrophysiologist and a columnist. As a clinician, I came away happy to see friends and to have learned a few new tricks.

But as a chronicler of science, I came away disappointed. The once fast-moving field of EP is stuck. There were no major advances. The so-called late-breaking trials were mostly observational studies.

The enthusiasm surrounding the three most popular themes at HRS came with scant evidentiary support.

Cardioneural Ablation

Cardioneural ablation promises to cure (mostly) young people from debilitating bradycardia. The idea is to ablate sites in the atrium adjacent to ganglionated plexi. These "GP" sites are close to the areas we target during ablation for atrial fibrillation (AF).

Enthusiastic and charismatic proponents described case reports of amazing cures to packed rooms. The presenters showed beautiful images of the heart rate increasing after burning, and then reports of no more pauses. Young people saved from needing a pacemaker — it has a bit of a magical feel.

But a neutral observer sees many problems. The main one is history. The first vasovagal pacemaker study found that these devices worked to prevent syncope in patients with vasovagal syncope. Pacemaker recommendations followed.

The same authors, 4 years on, published the VPS II trial which had a sham control arm and proper blinding. In VPS II, all patients got a pacemaker, and half were randomly assigned to pacing switched on and the other half to pacing switched off. Now there was no difference in recurrent syncope.

Cardioneural ablation is exciting. You see its effects often during AF ablation wherein the resting heart rate increases when ablating areas close to the pulmonary veins, presumably from vagal denervation. It's reasonable to think that this ablation effect could help people who struggle with syncope from vasovagal episodes.

This invasive procedure desperately needs a sham-controlled trial and long-term follow-up. The only thing holding this procedure back is the lack of a billing code. If not for reimbursement challenges, I worry that it would not be long before therapeutic fashion shredded the equipoise needed to do a proper trial. Witness the uptake of left atrial appendage occlusion in the past 6 years.

Pulsed-Field Ablation

During talks on AF, I show slides depicting the success rates of AF ablation in 1998 vs 2022. These are worthy images because, despite innovation, success rates haven't improved substantially.

My theory of why we aren't better at AF ablation is because nearly all of the innovation has focused on better ways to destroy cardiac tissue.

We have a target problem. We treat AF as if it were an aberrant pathway that needs to be destroyed, as in Wolff-Parkinson-White syndrome. But AF is far more complex. Rare is the case of AF from a single source that can be ablated.

While it's good to have fancier mapping systems and catheters that make more reliable lesions, the focus needs to be far upstream from creating scar in the atria.

That is the problem with pulsed-field ablation (PFA). Rather than advancing knowledge of AF mechanisms, it is simply another way to scar the atria. PFA works through something called electroporation wherein electrical pulses create tiny pores in myocyte cell membranes. These pulses (or shocks) cause cell death. The purported advantages of PFA are speed and presumed cardioselectivity.

At HRS, PFA created a buzz. One reason is American optimism, which is sort of nice — though sometimes our optimism blends into gullibility. PFA also has the support of key opinion leaders. And given the cuts in AF ablation reimbursement, the promise of faster procedures doesn't hurt.

Yet, PFA has not been tested in a randomized trial. Preliminary data suggest that success rates are not much better than those with traditional ablation. The large EU-PORIA registry series, presented as a late-breaking study at HRS, produced some good and bad news. Good is that the procedure is fast, the learning curve short, and success rates decent. But the bad is the serious complications listed: stroke, tamponade, phrenic nerve dysfunction, air embolism, and coronary spasm. Another late-breaking study of PFA reported long-term outcomes in just 116 patients.

Conduction System Pacing

Cardiac pacing is one of the purest forms of medicine. Sick people are asking for our help and pacing relieves their symptoms, often immediately. The downside of standard ventricular pacing is that it creates a dyssynchronous contraction which leads to pacing-induced cardiomyopathy in 10%-20% of patients.

Four late-breaking clinical trials at HRS addressed conduction system pacing (CSP). But only one was an actual trial — a small (N =100) RCT looking at echo parameters at 6 months. Three of the papers were observational comparisons to cardiac resynchronization therapy.

Numerous lecture sessions and posters involved pacing the conduction system, which has now evolved from His-bundle pacing to left bundle branch–area pacing. Every session on CSP that I attended was standing-room-only.

In the matter of CSP, I must report a tension between my skepticism of new therapies and my extreme enthusiasm, especially for left bundle branch–area pacing, which is easier to do and produces far more reliable pacing parameters than His-bundle pacing.

This tension came into full view during a lecture I gave on CSP at the Portuguese Society of Cardiology meeting. In the Q&A, a young doctor came to the microphone and asked me how I squared my aversion to highly promoted unproven new therapies with my enthusiasm for this technique. The moderator agreed with her; he, too, was skeptical of CSP.

This interaction made me think. I feel certain that CSP will prove a worthy practice. But I am sure that there were doctors equally sure that suppressing PVCs after MI was the proper strategy until it wasn't.

Fortunately, my colleague, Mihail Chelu, MD, PhD, convinced the US government to fund a proper outcomes trial, called Left vs Left. I am pleased to participate in such an important test.

My HRS Takeaway

The fate of these three hot topics is unknown. CSP looks the most promising, but time and more evidence will be the judge.

For now, electrophysiologists continue to do great work in the care of patients. I love this field because we can help people using the advances made years ago.

The core problem facing electrophysiologists today has changed. In the past, the problem was that we didn't have enough treatments for people. Now, the challenge is whether we should intervene. It's hard to have late-breaking trials on that.

Plateaus are surely part of science. In fact, this year's HRS reflects the reality that science is hard and progress comes slowly.

John Mandrola practices cardiac electrophysiology in Louisville, Kentucky, and is a writer and podcaster for Medscape. He espouses a conservative approach to medical practice. He participates in clinical research and writes often about the state of medical evidence. 

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