Melanie Cole, MS (Host): UAB is using a new technology to treat atrial fibrillation known as pulsed field ablation. Welcome to UAB MedCast. I'm Melanie Cole and joining me today is Dr. Tom McElderry. He's an Assistant Professor, the Section Chief of Electrophysiology and the Co-Director of the UAB Heart and Vascular Venter. Dr. McElderry, thank you so much for joining us today. Can you give us a little bit of an overview of pulsed field ablation or PFA and its role in the treatment of AFib? How does it target and disrupt the electrical pathways responsible for AFib? Some of the mechanisms underlying its efficacy and tell us the primary advantages compared to traditional radiofrequency or cryoablation techniques.

Tom McElderry, MD: Thank you for having me today Melanie. Pulsed field ablation is an exciting new addition to our toolset for the treatment of atrial fibrillation. We presently use either radiofrequency, which is heat or cryotherapy, which is cold, to freeze tissue in order to treat areas that we think are important in atrial fibrillation.

Each of those technologies has their own shortcomings. With the heat with radiofrequency ablation, we're concerned about heating to the esophagus, which sits right behind the heart and in the very worst case you could have some damage to the esophagus that created a left atrial esophageal fistula.

Now, thank goodness that's rare, but we certainly want to eliminate all complications. With cryo and with RF, there is a risk of injury to the right phrenic nerve during parts of the procedure and pulsed field ablation offers the opportunity to avoid both of those. Pulsed field ablation is a very high energy delivery in a series of packets or pulses over a short duration of time.

We're able to sort of tune if you will, the energy waveform to selectively target cardiac tissue and selectively avoid injury to the esophagus and the phrenic nerve. So it's really been a terrific opportunity for us to try to improve the safety of the procedure and as a bit of a bonus, because the energy is delivered so rapidly, procedure times can actually decrease.

Host: Well thank you for telling us about those advantages compared to traditional radiofrequency or cryoablation as you were discussing and you, Dr. McElderry, had the opportunity to assist in the development of this technology from cadaver studies in Seattle, preclinical studies at UAB and in Bordeaux and in the first manned studies in Paraguay. This is so awesome. Can you tell us about this?

Tom McElderry, MD: Well that was certainly an exciting time. I personally was able to assist in some of the development. There's a tremendous amount of work that's put in by the company and the engineers and I was certainly happy to play my part but it was nice to see the technology develop over a series of years and then to be able to bring it into the clinical trial here in the United States that ultimately led to approval of the technology.

Host: Well, that leads us well into the next question. You were also participating in that IDE clinical trial that led to the approval of the technology here. Tell us about the trial.

Tom McElderry, MD: Oh yes. Well, the trial randomized patients between our traditional therapy options using cryo and RF versus new technology which was the FARAPULSE, pulsed field ablation system and that study showed that the FARAPULSE technology was faster and eliminated the complications of phrenic nerve injury and left atrial esophageal fistula.

Host: When we think of patient selection, who would benefit most from PFA? Are there specific characteristics or comorbidities that would make individuals better candidates for this procedure, or is it pretty wide open selection?

Tom McElderry, MD: I think it's really more towards a wide open selection. If you look the ADVENT, the clinical trial with pulsed field ablation and some of the other therapy options that we have, the success rate, the efficacy rate for all the technologies is comparable. So it really becomes a choice between the doctor and the patient to decide what energy source is best for the patient.

Currently with the pulsed field ablation technology we have that's market released, it works really well for patients who need pulmonary vein isolation alone but the catheters don't necessarily tailor themselves for ablation outside the pulmonary veins. I believe we're going to see over the next year or two, other vendors come to the market with other therapy options which would allow for ablation outside the pulmonary veins as well as isolation of the pulmonary veins. So it's not the sort of thing where we've decided to wholesale, change over and only use pulsed field ablation, but there's certainly a role for that in a good number of patients.

Host: Well there certainly is. This is just such an exciting time in your field. What about the procedural aspects of PFA? Equipment, duration, are there any advantages in that regard and speak a little bit about the learning curve for other providers.

Tom McElderry, MD: The equipment is not terribly dissimilar to our current equipment. The sheath size is a little bit larger to accommodate the pulsed field ablation. However, we're very fortunate that another vendor has come up with a larger vessel collagen vascular sealing device so that we haven't had much in the way of issues with oozing or bleeding at the access site in the leg after the procedure.

 With any new technology, there's a learning curve. Now, I certainly have the benefit of having a lot of my learning curve in the preclinical model but, we always continue to learn. Some of the things that we've learned with the FARPULSE technology is that it's important to understand the contact relationship between the catheter and the tissue and that using intracardiac echo, is essential in ensuring good lesion quality and delivery. And I think as time goes on, we'll be using some other impedance based mechanisms for a better understanding contact between the catheter and the tissue.

Host: That's interesting when you're talking about the interoperative imaging that's going on and in your opinion Dr. McElderry how might PFA shape the future landscape of AF treatment? Where do you see this headed? You said that other vendors are going to come around. We're going to look at the safety profile. What do you see happening or what would you like to see happen in the next 10 years?

Tom McElderry, MD: I think you're going to see the procedures become much more efficient. Currently patients don't even have to spend the night for the most part when we do these procedures. I think we're also going to find that efficacy of our energy delivery and our lesioning is going to go up and it's going to afford us the opportunity to ablate in other regions that we once felt were relatively unsafe, that we'll now be able to ablate much more easily. Namely the left atrial appendage and the superior vena cava.

Host: Dr. McElderry, are there any ongoing clinical trials that you'd like to mention that you'd like to let other providers know is going on at UAB?

Tom McElderry, MD: Yes. Thank you for asking that question. We're currently enrolling in the Avant Garde study. It's a study FARAPULSE technology that randomizes patients between early medical therapy and early ablation therapy.

Over the last several years, we've had a number of studies that have shown that the earlier that we do an ablation and intervene in the disease process of atrial fibrillation, the patients do better. They have less heart failure. They have less hospitalization for atrial fibrillation, and perhaps less stroke as well. And so this study will take people who are relatively new to atrial fibrillation and allow them the opportunity to have ablation much sooner than I think doctors traditionally think about this and has the opportunity to really change the paradigm on how we think about atrial fibrillation. When I started my career, patients used to have to fail multiple drugs before we even considered ablation and we allowed the horse to get out of the barn and the disease process to really carry on a fair amount before we tried to intervene.

And I really think that intervening earlier is gonna result in much better long term outcomes for our patients

Host: Do you have any final thoughts, key takeaways for other providers, what you'd like them to know about pulsed field ablation and what you're doing, the work you're doing at UAB?

Tom McElderry, MD: Absolutely. I think pulsed field ablation is an exciting field. I think that each pulsed field ablation system that you see is different and that the waveforms are different and they're not necessarily interchangeable so that we need to look at each system on its own merit and its own clinical studies as we evaluate incorporation of that technology into our practice.

And something that we already touched on was the learning curve and the real need to use imaging in order to ensure adequate catheter contact. I think as time moves forward, we're going to have some impedance based mechanisms to understand that. One of our vendors is going to have a force sensor so that we'll better understand it in a non binary fashion and I see that this is really a great step forward for us as electrophysiologists and ablationists.

Host: Thank you so much Dr. McElderry. What a fascinating conversation. Come back and join us again as this progresses and thank you again and for more information please visit our website at uabmedicine.org/physician. That concludes this episode of UAB Medcast. I'm Melanie Cole.