Western Atrial Fibrillation Symposium 2025: Session 9 Roundtable

Surgical MAZE and Hybrid Procedure—Patient Selection

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Edited by Jodie Elrod

Featured is the Session 9 Roundtable entitled "Surgical MAZE and Hybrid Procedure—Patient Selection" from WAFib 2025. 

Andrea Natale, MD: It's a pleasure to be the co-chair with Dr Nazarian and have discussants Drs Jamil Borgi, Michael Riley, and David DeLurgio. This is the roundtable session entitled “Surgical MAZE and Hybrid Procedure—Patient Selection.” Let's start from the EP side with David and Luigi, and then go to the surgical side. 

Luigi Di Biase, MD, PhD: Over the years, we have seen a lot of procedures done surgically. My opinion is that if you have a good surgeon who has an EP practice that routinely does them, and we have an expert here, then surgeons can do this. However, if they attempt to do it and they are not EP surgeons, it does not work. So, there are some patients who can benefit from it, but only the ones who undergo surgery. Also, now with pulsed field ablation (PFA), things have changed because more operators go beyond pulmonary vein isolation (PVI) and feel comfortable with that. So, I think with PFA and more aggressive ablation, the hybrid procedure will limit this only to the people who are undergoing surgical ablation.

David DeLurgio, MD: Thank you. I believe that hybrid therapies have a role that we shouldn't forget. The database for response to hybrid therapies is impressive, where in advanced atrial fibrillation (AFib), I think our endocardial approaches are still in development. Of course, PFA holds a lot of promise and there is a lot of enthusiasm, but we're not initially seeing a signal that PFA is able to get the same results that we can get from a surgically based or hybrid procedure. So, I tend to look at patients with advanced forms of AFib as potential candidates for hybrid therapies. That doesn't mean I won't try a more advanced PFA-type procedure first. It will sometimes be the case, but I think we must acknowledge that our database for successful posterior wall isolation is emerging and has not really shown yet that it is helping our patients with advanced AFib.

Michael Riley, MD: I would add that at our institution, we have a fairly well-established hybrid ablation program. We've been collaborating pretty closely with our surgical colleagues for more than 10 years now, doing 700 to 800 hybrid ablations. Using that collaborative heart team approach where EPs work closely with surgery, the outcomes are significantly better.

Andrea Natale, MD: Let's see what the surgeon has to say. 

Jamil Borgi, MD: I have both the privilege and unfortunate luck of being at multiple institutions, so I would say that there is great variability about collaboration between surgeons and electrophysiologists depending on the institution. Even for concomitant surgical ablation, I would mention the Society of Thoracic Surgeons survey that showed no more application than 50% to 60% nationwide. So, a lot can be made about collaboration. With the strong evidence about hybrid procedures, more surgeons are going to be involved in this, particularly because it's a relatively easy thing to do. Dr Damiano will likely have a different outlook. 

Ralph Damiano, MD: It's an excellent question and a good thing to look back on. First of all, we've been doing surgical ablation for AFib since 1987, certainly at our institution, with a basic lesion set that has stayed pretty much unchanged during that time. The MAZE procedure is a biatrial lesion set that we started with and I think that is an important factor of getting very high success. To put it into perspective, with surgical ablation, this conference is focused on standalone, which is lone, nonvalvular AFib. But you must remember that in surgical ablation, 95% of our procedures are concomitant. It's very common in patients being referred for surgery to have AFib. In fact, it's an area this conference could probably expand upon. In most international studies, the most common cause of longstanding persistent AFib is valvular heart disease. If you don't fix the valve problem, ablation almost never works. So, concomitant ablation is really important. I think Jamil is right in that it has been relatively underperformed, but we've made huge progress in the last 20 years in educating the surgical population on how to do an accurate MAZE procedure, and people are getting better. It is a legitimate criticism that Luigi made that at a lot of centers, the surgeons do not have the expertise and it's different. However, in the concomitant space now, we have much better expertise due to the FDA mandating companies to do education on ablation technologies and procedures. But it is increasing. If you look back 20 years, the number of concomitant ablations were so small that it didn't even register in our national database. Now, in the mitral population, we want it to be 100%, but we've gone from very close to a handful of cases up to almost 50,000 ablations last year. So, we're making progress. We have a ways to go, but I would say that all cardiac surgeons should be well-versed in how to do concomitant ablation. I would agree that in the standalone, in my opinion, there is still a place for a full MAZE procedure in those patients who have failed catheter ablation, and particularly, it was interesting in the redo procedure where 40% of patients had sources in the right atrium. That is something we also found in both our epicardial mapping at the time of surgery, but also ECGI mapping; about one-third of patients in that 30% to 40% range have right atrial sources and the MAZE is a biatrial procedure. In patients who have failed multiple catheter ablations and probably have non-left atrial (LA) sources, a minimally invasive, full biatrial MAZE can be done with the fantastic ablation technology that is now available. Our group and others have shown that our lesions are durable and we have excellent results out to 10 years. So, I think that it has a place, but it is a small place. I think it is in the group of patients with a large LA. We've also talked a lot today about obesity. But you must remember, in patients who are obese, they can develop pulmonary hypertension and there is a significant number of those patients with biatrial enlargement. If you fail a number of catheter ablations and have biatrial enlargement, I think a surgical MAZE is still excellent in that group of patients. I'd agree that with hybrid ablation, there are probably more hybrid ablations now being done in the US than standalone MAZE procedures. The data is excellent with 3 randomized trials showing that in high risk or longstanding persistent AFib, it seems to have a real long-term advantage over catheter ablation. But that is going to be center dependent. There is always new technology, so we'll have to see, but I think it definitely plays a role.

Saman Nazarian, MD, PhD: I want to ask a surgical question to the electrophysiologists. My practice has been if I see severe mitral regurgitation (MR), I will send the patient for surgery and a concomitant AFib procedure, but I want to hear from you about what the key clinical factors are beyond those things that I mentioned and also failure or duration of AFib. Are there things by imaging beyond LA size? Are there patient factors that you consider where you say this would be better handled by hybrid? Please make the distinction between hybrid versus surgical MAZE. 

Luigi Di Biase, MD, PhD: I will start. There is no doubt, and Ralph already said that if it is a valvular patient and the valve needs to be fixed and requires surgery, that should come first. Then, depending on the type of surgery you have, consider an ablation depending on the expertise of the surgeon. But again, if it is valvular or there is a problem, the surgical procedure comes first. If the patient does not need surgery, then I start thinking of a different option. Our group and my mentor Dr Natale believe that when the LA is enlarged and there are other comorbidities, such as PVI nonresponders, then depending on the expertise of the electrophysiologist, if you feel you can go beyond PVI and do the posterior wall, superior vena cava, and right atrium at times, or the left atrial appendage (LAA) in some cases, then do it yourself. I think PFA is increasing the number of people that can do more beyond PVI. Before we moved to PFA, alcohol ablation was a way to burn less in the LA. But if you are not comfortable doing that, then for a hybrid procedure, the outcome is good if the posterior wall stays isolated. If you think you can do it by endocardial ablation, it is probably better for the patient. But if you know you cannot do it and have a surgeon who can help you, then hybrid has a role.

Saman Nazarian, MD, PhD: David and Mike, would you like to expand on your criteria for selection for each of these options? 

Michael Riley, MD: Sure, I would say that it's very important to point out that a comprehensive hybrid ablation program is more than just a Convergent procedure. Many of the patients that we see now are getting a concomitant surgical ablation, and because we work so closely with our surgical colleagues, typically what happens for those patients is that EP is consulted when the patient sees their surgeon during the preoperative phase. So, we are involved early on in the management of those patients. Oftentimes, the patient is having surgery for a valvular issue, so they have surgical ablation and EP follows those patients, which ensures good follow-up. For recurrent arrhythmia after ablation, we typically take an endocardial approach.

David DeLurgio, MD: Saman asked a question about enhancing patient selection. It is very difficult in the PFA world to say that a patient who doesn't have valvular disease but has advanced AFib should definitely go for a hybrid procedure, because we don't know if we cannot help that patient with a standard endocardial procedure. So, we want to do more, but we don't really know how to decide in all cases. We end up using sort of “hybrid” factors, if you will, that tell us whether this patient truly has advanced AFib. It's not just the duration, but atrial size often plays into it because that correlates very strongly with atrial myopathy, which often involves the posterior wall. I'm very convinced by the MRI data that has been put forward by Nassir’s group, the Bordeaux group, and others, all showing this tendency towards developing a myopathy that involves the posterior wall. Dr Damiano discovered several decades ago that you must ablate the posterior wall in these advanced AFib patients to get a good response. So, when we use PFA, we think we can now ablate the posterior wall and completely silence it easily. That may be true, but we must remember that when we looked at the PFA studies now that isolate the posterior wall, we're not really seeing a big increment in outcomes. As a matter of fact, we're seeing no increment in outcomes in the published data. Why is that? Maybe we selected the wrong patient to isolate the posterior wall. We learned from the first randomized hybrid study, CONVERGE, that the patients who had less advanced AFib actually didn't get that much improvement from adding the posterior wall. So, it was really the patients with the more advanced forms where the difference over the first year or first year and a half was dramatic—in other words, less recurrences and the delta even grew over time, presumably because of the durable effect we had on that substrate. So, as we try to select these patients, we're going to have to determine if the patient is highly likely to get a good response to hybrid or not very likely to get a good response to an endocardial-only approach. We must make that choice. Once we fail with an endocardial approach, we should be thinking about how to make the next procedure really useful, and that may be a hybrid approach.

Michael Riley, MD: I would also say that when we see these patients with advanced AFib, persistent AFib with large atria, or longstanding persistent, we should have the conversation about hybrid ablation pretty early. But oftentimes, when given the option, patients choose endocardial ablation first, which I think is perfectly reasonable. Because we now have PFA available, we have a lower threshold for doing ablation outside the PV, so we're frequently doing that where we ablate the back wall. We know it's safe, but I guess we don't know yet if it's going to be effective.

Saman Nazarian, MD, PhD: Let me follow that with a question for our surgeons. One thing that comes to mind is we're often sending you the highest risk, most difficult patients. So, when you evaluate some of these referrals, tell us how you weigh the risks of invasive surgery in these patients who are necessarily selected to be the higher risk, obese, diabetes, or chronic kidney disease type of patients.

Ralph Damiano, MD: I can start with that. This has always been our patient population. We're used to seeing obese and diabetic patients; they are the majority of our coronary patients, and in the west, at least in the US, of our valve patients. We've been doing a minimally invasive, full biatrial MAZE. We have fantastic technology now that we've done with all-comers and they have an average duration of AFib of almost 7 years and have failed an average of 2 catheter ablations. The majority of my patients seem to be obese; they're the ones who particularly seem to be referred by electrophysiologists for surgery since it’s more difficult to put obese people on the EP table. I think with modern surgical techniques, and we do our MAZE procedure always on bypass, but we've now done almost 350 consecutive cases over the last 15 to 20 years with no mortality. We're used to these risk factors, and compared to our average cardiac surgical population, it's not too bad. That said and done, we obviously complete a fairly extensive workup, particularly in those patients with pulmonary disease, and all our patients have either computed tomography (CT) or an MR angiogram to ensure they don't have a lot of vascular disease. Clearly, there are patients who we feel if we cannot do a MAZE procedure with a very low mortality, we usually will not recommend they go ahead. The one advantage of a surgical MAZE is the clips that have been recently introduced have given us a very reliable and easy way to manage the appendage without having any intracardiac foreign body. That has been a great advance in the surgical area, particularly for minimally invasive, where we can do it very quickly and effectively. So, I think they need to be evaluated, but most of the patients have been surgical candidates.

Jamil Borgi, MD: For the hybrid approach, most of these patients are surgical candidates because of the low risk of the operation. But when we are talking about a minimally invasive biatrial or bypass approach, it is a completely different risk stratification. I think this is what was meant.

Ralph Damiano, MD: The only thing I would mention about a hybrid procedure is that for most of the panelists here, if you had failed a number of ablations, there would be zero chance that I would do a hybrid. I'm just redoing non-posterior wall and LA sources. That is the advantage of the MAZE if you have some indication, right atrial enlargement, most of the patients with HFpEF, or any type of pulmonary hypertension and large atria. I am a big believer in hybrid ablation for the de novo patient. I think it's problematic in patients who have failed from good centers. When we looked at our data 10 years ago, most of the time when we got in there, the PVs weren't isolated. But now, three-quarters of the time when I'm doing it and we check for epicardial exit block, the PVs are isolated. I think with a lot of your mapping, contact force, and intracardiac echocardiography, you're doing a great job in the PV area, but there are either small gaps that have been left or there are sources in both. One thing we have in surgery is that with a clip, we can completely get rid of the appendage and we do a full right atrial lesion set. Both our center and others have shown you can get right AFib. Both our group and Mayo have had large series of performing right atrial MAZEs in congenital patients with tricuspid atresia. So, you can definitely get it and that is an advantage in this failed catheter ablation group.

Luigi Di Biase, MD, PhD: Ralph, you are like an electrophysiologist. There are many of us who don't do what you described, which is checking for exit block when doing procedures. That is why I feel the message needs to be clear, because if people are educated and do the procedure your way, then there is a reason. But I know many surgeons who ablate biatrially and get out. So, that is the difference that makes a center qualified for surgical ablation versus not. The same applies for EP. There are many of us who just do the vein and never in the past checked if they achieved isolation with any exit block. So, the field needs some important parameters to be respected. 

Walid Saliba, MD: For the non-electrophysiologists Jamil and Ralph, I want to backpedal to what you said about valvular heart disease. One of the things that I struggle with a lot in the clinic is when you have somebody coming in with AFib and their echo shows moderate to severe MR. We struggle with if the valve is prolapsed, and wonder how much of this is secondary remodeling and how much is truly MR. I wish we had a cardiac imager here to weigh in on that. How much is the surgeon’s role in looking at the echo and the valves? Can you make a point in terms of doing the AFib ablation and seeing what happens? Or, can you clearly go ahead and fix the valve and do a MAZE and clip the appendage at the same time?

Jamil Borgi, MD: The way I approach this is to identify how long they've been in AFib. You're describing MR that is secondary to annular dilation, not necessarily to prolapse. If there is prolapse or actual leaflet pathology, then we know this is mitral in origin and I would proceed with mitral repair and MAZE concomitantly. However, if it's AFib that is longstanding and even causing the annular dilation, I would still proceed with ring annuloplasty (valvuloplasty) and a MAZE procedure. But I'm not sure there is enough evidence that this is actually the solution.

Walid Saliba, MD: To add to this question, there is also evidence that early repair is beneficial in terms of delaying progression of AFib. So, we are back to not only early AFib ablation but early mitral valve repair. So, we're stuck. The surgeon sometimes tells us it is not bad enough to warrant doing something like this. Is the presence of AFib an accelerator for the patient to get surgery?

Ralph Damiano, MD: That is a fantastic question and something we deal with a lot. First of all, I'd say it's not uncommon. In a case we did last week, the patient had failed a couple of ablations, and the whole time they kept saying it was mild to moderate MR, but when we got the transesophageal echocardiogram (TEE), it was severe. So, the first thing is for the patient to get a TEE—that is critical. Transthoracic imaging is not accurate enough and you can really underestimate MR, especially with the eccentric jets in some patients. For those patients, we always evaluate with a TEE and try to rule out degenerative or MR due to mitral annular calcification, which isn't going to get better and needs to be addressed. A hot topic in the surgical field is called atrial functional MR, which is due to AFib, and it absolutely can get better. Ten years ago, I had a patient sent to me for mitral and tricuspid repair and a MAZE, but she never had AFib. They had done an echo that showed moderate MR / moderate TR, but no one had ever cardioverted her. So, we tried cardioversion, and she went back to sinus rhythm and didn't even need an ablation. I followed her for the next 3 years, and both her MR and TR went away, and she stayed in sinus rhythm. So, in some of those patients, if they haven't been cardioverted, see what happens with MR/TR with a cardioversion first. It might depend on how much you think the remodeling has, and it takes some judgment there. For someone with new-onset AFib, it's worth trying to get rhythm control first in a nonsurgical way and see what happens. But in a patient with either longstanding AFib or a really large atrium, it's unlikely that will change much, and they probably need both. Regarding repair in those patients, once they have severe MR, it's pretty obvious they are going to need the repair. As Jamil was saying, it is a pretty easy ring annuloplasty (valvuloplasty) and it works very well in that population. However, in the surgical literature now, we don't have a lot of good data on atrial functional MR. We're developing it now. It seems to respond quite a bit better to a reduction ring annuloplasty, for instance, than ventricular functional MR has, but it also can get better with restoration of sinus. That is a really great question and one that I think is going to be an area of a lot of investigation in the next 5 years.

Luigi Di Biase, MD, PhD: Ralph, when you said biatrial ablation, which in some patients with persistent AFib and a large right atrium, I agree it would work, but if you're operating on a patient with paroxysmal AFib that is nonvalvular, would you do the MAZE with biatrial or just one atria?

Ralph Damiano, MD: That is a good question and it's a lot different for a surgeon than for an EP, because you can quite easily go back in, even it's an outpatient procedure. However, surgeons have one shot at surgery, and ablation is an ideal environment. First of all, we have a bloodless field, we don't have to worry about that. Both the bipolar clamps and cryo have virtually no collateral damage, and we can see everything we're doing. So, it depends. According to our data, about 93% of the time, I do a biatrial procedure because I'm there only once. They have one shot. In our follow-up of patients, we can see recurrences of AFib after a MAZE procedure as far as 8 or 9 years later. So, I always tell the people I'm training that they are going to want to treat not only the AFib the patient has now, but they also want to treat the AFib the patient may have 5 or 9 years from now. There is very little morbidity and maybe a slightly higher pacemaker risk—that is the only thing that has been shown. But otherwise, there is very little morbidity to a right atrial procedure. It takes care of typical flutter. It's very effective for that. So, most of the time I'll do it. We've shown that the paroxysmal patients will have a higher recurrence rate if you do only the LA depending on the duration. So, if it's a very short duration, they've had 1 or 2 episodes and a patient without a huge atrium and no right atrial enlargement, I think a left atrial MAZE works well. It's interesting, isolated PVI with our clamps has been abandoned surgically. Our recurrence rate has been extraordinary in every group, even in paroxysmal, once you get out to 5 to 8 years, they've all recurred. So, we find PVI with these bipolar clamps, which is much less than you do with a wide area ablation PVI, has an extremely high recurrence.

Andrea Natale, MD: It sounds like they're telling us to end. Thank you to all the people on the panel and my cochair.

The transcripts have been edited for clarity and length.