Intro: Welcome to UAB MedCast, a continuing education podcast for medical professionals, providing knowledge that is moving medicine forward. Here's Melanie Cole.

Melanie Cole, MS (Host): Welcome to UAB MedCast. I'm Melanie Cole. And today, we're speaking about current management of atrial fibrillation. Joining me is Dr. William Maddox. He's an Associate Professor of Medicine in the Division of Cardiovascular Medicine in the section of Electrophysiology at UAB Medicine.

Dr. Maddox, thank you so much for joining us. When you look at AFib, the landscape today, compared to even five years ago, what stands out to you as the biggest shift in how we diagnose, stratify, and even manage these patients? You and I did a previous podcast on this topic. Why are we updating it? What's exciting?

William Maddox, MD: Thank you for having me, Melanie. It's always great to come here and be able to talk a little bit about some of the interesting things that we do at UAB. The management of atrial fibrillation has really changed dramatically in the last several years. Atrial fibrillation is the most common sustained arrhythmia that we see. And as our population ages, we're just seeing more of it. I had 40 people in clinic yesterday and 29 of them had atrial fibrillation So, it is certainly a common disease process that we're managing on a daily basis.

The most exciting thing that we've seen in the last several years is that our treatment for symptomatic drug-refractory atrial fibrillation. The mainstay of treatment has always been either cryoablation or radiofrequency ablation, which are two different treatment modalities for delivering energy and isolating the pulmonary veins and other arrhythmogenic areas in the atria. And what has now come to forefront is pulse field ablation, which is a new modality for achieving the same efficacy with some hopefully increases in safety and as we're finding some novel areas that we can treat that we weren't as successful with or couldn't treat, because of risks to contiguous structures such as the phrenic nerve or the lungs or the esophagus.

Melanie Cole, MS: Well, thank you for that. So, I mean, it is an exciting time in your field, Dr. Maddox. So, let's talk about pulse field ablation. It's now becoming a mainstay of treatment for energy delivery. So, speak a little bit about that. How has that broke onto the scene? What's it doing for you?

William Maddox, MD: Sure. Pulse field ablation, this is electroporation of the cells of the myocardium. And this is actually a treatment modality that has been used for years for to deliver chemotherapeutic agents and other medications to specific cells within the body. And it had been used in the treatment of solid tumors and other things.

And what it does is it passes an electrical impulse through the cell, and then permeates the cell membrane to allow traditionally the cell membrane to be more receptive to intake of chemotherapeutic agents and other biologic agents. Traditionally, it had been used for this delivery of drugs and it was something that we tried to have reversible damage to the cell, such as the cell would become more permeable for a period of time, and then would repair itself, and that permeability would close.

Pulse field ablation, when we're using it for ablation is we're looking for permanent, irreversible damage to those cells such that the cells undergo programmed cell death, and that we create a line of scar so that the electricity can't pass from pulmonary veins or other arrhythmogenic tissue. And that the arrhythmia can continue to propagate.

One of the challenges that the industry and the field in general has had was creating waveforms of electrical energy that would pass through these cells that would be successful in permeating the cells and then causing irreversible cell death, but didn't damage any contiguous structures. And that is a topic for another time, and I'm not an expert. There are some really smart engineers who have spent years and in their entire career helping to develop these things. We've learned more about it. And the way that the electricity is delivered to those cells can be very selective to the cardiac tissue. That allows us to target the myocardium, but hopefully spare the energy delivery to things like the esophagus, the lungs, the phrenic nerve.

Melanie Cole, MS: So Dr. Maddox, then, what are you seeing in terms of durability, reconnection rates, long-term freedom from arrhythmia? It's been described as kind of a workflow changer, particularly regarding tissue selectivity, safety. How is it altered for you-- procedure times recovery, all of those things?

William Maddox, MD: Anytime that we introduce a new treatment modality to any of our arrhythmias that we treat, what we're looking for is, first, that we're just as effective as we were with our prior modality or our predicate modality. Hopefully that we are safer, and also that if we can be, that we're more efficient. And this world of more and more patients that need to be treated, increases in efficiency in the lab means that we can treat more patients and hopefully help more people and get them home in a timely fashion and back to the lives that they want to lead.

There are multiple companies that create these catheters and there's been several different that are now FDA approved. And so, with each iteration of what comes out, we've become better and more efficient at it honestly. Now, most commonly, we are using catheters that allow us to deliver both pulse field energy and radiofrequency energy. And we can be selective about where we do either one. Our efficacy has been equivalent to what we see with radiofrequency ablation or cryoablation. We're still seeing in our lab first-pass isolation, which means that as we go around the pulmonary veins on the left side of the right side with one pass around the vein, we get isolation of that tissue. We're seeing that about 95-97% of the time, which is equivalent, or even sometimes a little bit better than what we saw with RF.

The procedural times are shorter. These catheters are delivering larger lesions than what we see with our smaller footprint, radiofrequency catheters. The time has come down about 15-20%. And certainly, one of the most exciting things for us is that there are some very rare but devastating complications that can occur when we're bleeding in the left atrium. One of the most significant of which is atrial esophageal fistula. This is a devastating complication that if it occurs is many times fatal. And with tens of thousands of these now done in all of our preclinical research, we have not seen any damage to the esophagus with pulse field ablation.

That is probably because both the waveforms that we use are cardioselective, which means that they are damaging the myocardial tissue, but not the smooth muscle tissue, the esophagus, but also the field strength of the energy falls off fairly rapidly, such that the tissues that are farther away from where we're treating aren't seeing any increases in heat or any damage to cells. So, it's an exciting time for us.

Melanie Cole, MS: It certainly is. Are there specific patient groups, Dr. Maddox, persistent, as you said, refractory AF, older adults, structural heart disease, where this has more benefit, especially pronounced? What factors influence your choice when you're counseling your patients and thinking about shared decision-making?

William Maddox, MD: There's been a lot of information in the media about pulse field ablation. And many of my patients are very well informed when they come to me. So many times they're bringing it up as well and asking if we have the new technology. And they'll say PFA-- is what it's most commonly-- kind of the vernacular that they use.

The pulse field ablation is really our first-line treatment for patients that have either paroxysmal or persistent atrial fibrillation, that this is the first time that they're having catheter ablation. There are some considerations for areas that can be challenging with pulse field ablation, if the patient has a mitral valve that is metal, so it's a prosthetic mitral valve, or if they have other large structures that are metallic in the heart, there is some data That could be an energy sink from the electricity. And we may have inconsistent delivery of energy to the tissue that we'd like to treat. So if someone has a Watchman or an EM plaster device or something like that, that I'm worried that the energy might be pulled into that metal rather than go to the tissue like I expect. I'm usually using RF in those patients.

 Also, with the catheters that we have that allow us to both use RF and PFA, there is some data that sometimes the PFA may cause spasm of the coronary artery. So if we're treating very close to the coronary arteries, I'll simply switch to radiofrequency with that catheter for several lesions while I'm close to the coronary artery and then switch back to PFA once I feel like it's safe. We're able to see the coronary arteries in real-time using intracardiac ultrasound. So, that has not been a problem, and I haven't personally seen any coronary artery spasm, but that's mostly because I think we're pretty judicious about where we deliver energy.

Melanie Cole, MS: Well, it certainly is such an exciting time and an interesting time. Now, when we think of AFib, Dr. Maddox, besides PFA and the treatment modalities, monitoring is a thing. And in this world, as you say, of technology wearables, what are you seeing changing, monitoring, keeping track, helping your patients keep track or electronic monitoring for the medical staff?

William Maddox, MD: Absolutely. That's a great question. So for years, we've had loop recorders that can be placed on the anterior chest wall or multi-lead Holter monitors that the patient can go home with that allow us to record their EKG for up to 30 days typically. But now, with the advent of these wearables such as the Apple Watch, and multiple manufacturers now have the ability to have real-time EKG recording, many patients are coming to me and their first diagnosis of atrial arrhythmia comes from their wearable itself. These are quite easy. And with a watch on one hand and simply a finger from the other arm touching some electrode that the wearable has, you're able to reliably record lead one of an EKG fairly easily. And these, I found, have been quite useful for patients both in initial diagnosis of atrial fibrillation, but also for monitoring of recurrence after either medical therapy or catheter ablation.

Melanie Cole, MS: Dr. Maddox, as we wrap up, what would you like other providers to take away from the current management of atrial fibrillation? And what you're doing there at UAB Medicine that's so exciting?

William Maddox, MD: With more and more patients having atrial fibrillation, I want our providers out there to really have a thought getting these patients to us early in their disease process is our best chance of being able to intervene and make them symptom-free for the long-term. So if you see somebody with atrial fibrillation, sending them to us to take a look and see if medical therapy with either rate-controlling agents, anti-arrhythmic agents is best, or if proceeding with something like catheter ablation is in their best interest. These are day procedures. The patient comes in, it typically takes me about an hour procedure time to do, sometimes a little less. And after a couple of hours of bed rest, the patient is able to go home. The complication rates are very low. I quote people a little less than a 1% chance of complication and success rates are high. Patients in general are very happy with their arrhythmia control after an ablation. And the earlier we can see these patients before atrial myopathy and fibrosis occurs, the higher the likelihood that we can be successful.

Melanie Cole, MS: Great information. Thank you so much, Dr. Maddox, for joining us today. And for more information, please visit our website at uabmedicine.org/physician.org/physician. That concludes this episode of UAB MedCast. I'm Melanie Cole.