Nicholas Smedira, MD, MBA, staff cardiothoracic surgeon in the Department of Thoracic and Cardiovascular Surgery, and Juan Umana, MD, chair of Thoracic and Cardiovascular Surgery at Cleveland Clinic Florida, discuss considerations for septal myectomy.
Nicholas Smedira, MD, MBA, staff cardiothoracic surgeon in the Department of Thoracic and Cardiovascular Surgery, and Juan Umana, MD, chair of Thoracic and Cardiovascular Surgery at Cleveland Clinic Florida, discuss considerations for septal myectomy.
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Welcome to Cleveland Clinic Cardiac Consult, brought to you by the Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute at Cleveland Clinic.
Nicholas Smedira, MD, MBA:
Hi, I am Nick Smedira and I'm here with Dr. Juan Umana. We're here to talk about septal myectomy, which, Juan, is a really dynamic, changing practice in cardiac surgery. There's so much going on in the field of hypertrophic cardiomyopathy, so it's a real exciting time for the management of patients that we have so many things now in our armamentarium. So it's really exciting.
Juan Pablo Umana, MD:
It is. It is. I think that it's one of the most exciting fields right now, wouldn't you say? And not only from a medical treatment perspective with all the new options available, but as you've pointed out several times recently, surgery is still the backbone of treatment for these patients. I think there are a lot of questions as to what is hypertrophic cardiomyopathy and when it should be treated. And given that you're the expert in the field, not only at the Cleveland Clinic but worldwide, why don't you tell us a little bit what patients should be operated on and perhaps even being referred to a surgeon?
Nicholas Smedira, MD, MBA:
Oh, yeah. Well, there's a lot to unpack there, but for starters, hypertrophic cardiomyopathy is a genetic disorder. Interestingly, we thought the genetic disorder occurred in about one in 500, but in fact, it may be as common as one in 250. So if you do the math, that's a lot of patients that are potentially affected by this gene. Now, not everybody that has the gene will get that thick part of the heart, of the septum, but many patients will. So what we need is to understand what's going on with the heart in terms of obstruction. The blood has to get out of the heart, and the pathway is bordered by muscle on one side and the mitral valve on the other. And to effectively get out of the heart, there has to be a space for that. And in hypertrophic cardiomyopathy and in some diseases of the mitral valve, that space gets too narrow and the blood can't get out.
So to really understand what's going on, a patient with symptoms such as dizziness, maybe they even passed out, shortness of breath, especially interestingly after a meal. That's one of the hallmark signs of hypertrophic obstructive cardiomyopathy, a shortness of breath after a meal, which is very interesting. The patient then is seen by an imaging specialist who does an echocardiogram. Often you need to run on a treadmill to make sure the obstruction is identified, and then it's critical with either echo or MRI or a combination of those exams to understand how much of the problem is from the muscle which gets thick, or the mitral valve, which could be in the wrong position, it can be too long, any assortment of combinations. And that's where visiting a center of excellence that has the experience to identify what exactly is going on is critical. Then of course, it's important to have the surgical expertise to do what operation is necessary. What I do commonly is just shave the muscle. It's a relatively simple operation, and your expertise is the mitral valve, the mitral valve pathology and what can be going on. And here we've developed a number of unique operations that can help the mitral valve perform better without having to replace it. Our goal is to try to do things so the patient has their own valve, shaved muscle and avoid a mitral valve replacement. So that's sort of from the start through surgery that we've developed here.
Juan Pablo Umana, MD:
Yeah, I think... So if we take it from the top, kind of simplify, I think one of the things that is fascinating about the outflow tract or what it takes for the blood to get out of the left ventricle, it's not only the ventricle contracting, but the mitral valve interacting with the muscle, as you said. And when that muscle gets very thick, that mitral valve may just get almost sucked into that outflow tract. And that's when the expertise of a multidisciplinary team comes in, which is exactly what you've been working on here for a long time with imaging cardiologists, with echocardiographers, with MRI, as well as a clinical cardiologist that's dedicated to hypertrophic cardiomyopathy. The surgery itself sounds very complicated and very complex, but as you get down to it, Nick, it's really a relatively simple operation if you understand the concept, and you've done it several thousand times, right?
Nicholas Smedira, MD, MBA:
Correct.
Juan Pablo Umana, MD:
How often would you think that the mitral has to be repaired or intervened in hypertrophic cardiomyopathy? Because my experience is you can try to put a stitch on the mitral valve through the aortic valve, and that gives people peace of mind. It's called an Alfieri stitch, and some surgeons will do it routinely, but in my experience, it does not really make a difference. I think if your myectomy is extensive enough, the function of the mitral valve goes back to normal unless there's something clearly abnormal in the mitral valve, which is abnormally placed papillary muscles, abnormal cording. Why don't we talk a little bit about that?
Nicholas Smedira, MD, MBA:
Sure.
Juan Pablo Umana, MD:
Because if you include that, then maybe you need to intervene on the mitral valve more often than not, but actually repairing the mitral valve, working on the leaflets in my experience is relatively rare. What's your take on that?
Nicholas Smedira, MD, MBA:
I think if you look at the big picture of obstruction, blood getting out of the heart, I'd say the vast majority of the time it's the muscle and not the valve, to your point. And by cutting the muscle, thinning that septum, you open up enough pathway to let the blood out and the mitral valve behaves normally. Now we have a little bit of a referral bias because we've written a lot about the mitral valve being the primary culprit for obstruction. So cardiologists around the country, around the world send patients to us who have thinner septums. They're not very hypertrophied, but they still have obstruction. And when we started down this pathway, we saw this, and as cardiologists began to more intensely investigate a patient with symptoms, because in our minds as we just started to discuss, it was all about thickness of the septum, hypertrophy. And if you didn't see hypertrophy on the echocardiogram, you didn't think of obstruction because at rest, the obstruction might not be there because it often only happens with exercise or activity or a heavy meal.
Juan Pablo Umana, MD:
Which is why you were saying that it's important to do an exercise-
Nicholas Smedira, MD, MBA:
To provoke.
Juan Pablo Umana, MD:
Yeah, provoke the obstruction.
Nicholas Smedira, MD, MBA:
There's been so many patients, which is so regrettable when you hear the story, that have said, "I have had symptoms since I've been in high school. I couldn't do gym class. I went into the Marines and I barely made it through bootcamp. I was so short of breath." But then when they examine them at rest, they have no murmur, the echocardiogram looks perfectly normal, but if you had them do 50 jumping jacks in your office, or we often have them Valsalva, which can provoke the... You get the obstruction, but calm things down, you don't see anything. And that was very, very difficult. Patients are told they have asthma, people are told that they have anxiety, they have panic attacks, they see neurologists for dizziness, and it's this obstruction that may only be present when the heart's contracting.
So we identified patients that didn't have a lot of hypertrophy and asked just the fundamental research question, well, if you don't have hypertrophy and you're obstructing, what's causing the obstruction? And of course, it was the mitral valve. And then the question was, well, why is the mitral valve doing this? Because that then leads to thinking of surgical techniques that can intervene and putting a stitch may not be the answer once you understand the anatomy and the physiology. So then we started to look at how long is the leaflet? Because some mitral leaflets can be very excessively long, and that's causing them to flip up. I think potentially a couple causes. One is that when you're a fetus in utero, when the heart twists, the papillary muscles end up rotating in a position that puts them in the outflow path. So we've developed a technique to move them out of the outflow path.
Juan Pablo Umana, MD:
Oh, yeah. The mitral valve looks almost like a parachute, right?
Nicholas Smedira, MD, MBA:
It is. Yeah.
Juan Pablo Umana, MD:
It's held down into the ventricle by these cords that are attached to two muscles anteriorly and posteriorly that are the papillary muscles. When normally placed, they're in the anterolateral portion of the ventricle inside and posteromedial. Correct?
Nicholas Smedira, MD, MBA:
Yeah. Yeah.
Juan Pablo Umana, MD:
So you're saying that sometimes those can be slightly rotated and as a consequence be in the way of flow of blood?
Nicholas Smedira, MD, MBA:
That's what we've observed, and so we've focused on them for a bit to pull them back down away from the septum. So we have a couple of techniques to do that. I also think as we age, and maybe as we gain some weight, we lift up the heart a little bit as our diaphragm comes up, and that changes the angles of which the blood can get out of the heart. And so that predisposes patients to some obstruction. I think that's an explanation for why would somebody in their late 60s or 70 all of a sudden develop obstruction and then we do genetic testing and they don't have any of the genes that we know cause obstruction. I think what happens is they may have a little high blood pressure. They may have this change that occurs as we age, and the next thing you know you're predisposed to obstruction.
So these techniques that we've developed, these observations that we've made have led to us being more attuned to diagnosing the disorder and then having a couple of techniques to take some muscle, repair the mitral valve to open up the path. And it's been 25 years of working together in a center where we not only do the surgery, but we study the details of what we do. We combine the imaging aspect of it, and we've come up with, I think a fairly good way to then answer your question, how often does this occur in our referral where we repair the valve maybe 10% of the time?
Juan Pablo Umana, MD:
So really it's a small percentage, and the reason for that is we have a very deep understanding of the whole disease process and the pathophysiology of the obstruction, right?
Nicholas Smedira, MD, MBA:
That's correct.
Juan Pablo Umana, MD:
Now, when should a patient actually have surgery? Because a lot of these patients, many people will say, "Well, I do get short of breath when I go up a couple of flights of stairs." And if we're talking about a young person or not even young, mid-60s, who is getting abnormally short of breath, I advise those people see a cardiologist, have their heart listened to and maybe get an echo. And there are some markers that there might be an issue with the septum, with the heart being too thick. What are those? When should a patient get a stress test? When should you try to provoke that obstruction?
Nicholas Smedira, MD, MBA:
I think there's two times that we think about getting a stress test.
Juan Pablo Umana, MD:
It's an important thing to have done, particularly after, I don't know, 40 or 50 depending on your risk factors for sure.
Nicholas Smedira, MD, MBA:
For sure. If we have a family history of somebody with really gene-positive hypertrophic cardiomyopathy, we would recommend that the immediate family be screened with an echocardiogram. And if we see that there's thick muscle there, we would then recommend an exercise treadmill study, especially for the teenager who's thinking of going into playing soccer, running in track or lacrosse. It'd be a great thing to just make sure there's no obstruction.
Anybody that comes in with symptoms and say they get short of breath, dizzy, whatever it may be, we’ll do the baseline echo, will do some provocative maneuvers or we have them Valsalva. We give them this drug called amyl nitrite, which can provoke obstruction, and we see anything in that that's not quite reaching a high level of obstruction, then we do the treadmill. If we see obstruction with any of those tests, we know it's there and we don't necessarily need an obstruction exercise echocardiogram. But let's say we see obstruction, so the patient has some degree of obstruction, has some symptoms, the first line therapy in almost all patients is to start them on a drug that reduces the strength, the contraction of the heart, and that would typically be a beta blocker.
Juan Pablo Umana, MD:
It's important to point out that a good percentage of patients will get better-
Nicholas Smedira, MD, MBA:
With those, right?
Juan Pablo Umana, MD:
Because the obstruction is a function of how many times the heart contracts per minute, the speed of the contraction as well as the force of the contraction.
Nicholas Smedira, MD, MBA:
How strong it is. And the beta blockers reduce both of those things. Now, the problem with that is it's indirect. The drugs work indirectly in terms of the muscle itself, and they're not super well tolerated. Some patients have a lot of side effects. They can make you fatigued. Some people say it really knocks them down. It can produce sexual dysfunction in men. They're not liked. So the researchers for a number of years have tried to identify a drug that'll work directly on the muscle fibers themselves to reduce their ability, each fiber individually. And so they've come up with a class of drugs which are called myosin inhibitors, so that myosin is the protein within the muscle fibers that contracts, and one is available called mavacamten, and it is quite an effective drug.
So far in our experience, we've seen that it does reduce the obstruction, seems to be very well tolerated, but it's a lifelong therapy, the best we could tell, because once you stop the drug, within a matter of weeks the obstruction and generally the symptoms comes right back. But it is one of the new drugs in our armamentarium. The FDA has mandated that if you're going to take the drug, you have to be followed up very closely with echocardiograms on a monthly basis. And so there's a few centers that are doing it, and that's part of what we offer.
Now, which patients should be on this drug. Our recommendation, if you're a young patient with a significant degree of hypertrophy and obstruction, you want a cure that is lifelong and that's a septal myectomy. As you get older, you have other medical problems, surgery may be more challenging, may be difficult for you at this time, then a period of this mavacamten probably is a reasonable alternative. We reserve it for patients who we don't think are ideal candidates for surgery or at this time they don't want to undergo surgery.
Juan Pablo Umana, MD:
But you just pointed out something that I think we need to focus on, and it's the fact that myectomy is one of the few operations we do as cardiac surgeons that is actually curative. In my experience with myectomy patients, you find that the improvement in the quality of life is truly dramatic. Patients will come back to us even six weeks after the operation saying, "I've breathed better. I can golf again. I'm starting to go back to running." All of those activities that they had to give up on, all of a sudden it opens up. I find it very rewarding personally, particularly because the other thing is when you talk about open heart surgery, people go, "Oh, no, give me a drug anytime if I can avoid a big operation." The reality is this is curative and the risk of the operation is well within 0.5%, wouldn't you say?
Nicholas Smedira, MD, MBA:
Correct.
Juan Pablo Umana, MD:
What are the downsides to the operation? Aside from the immediate post-operative discomfort and pain, there is a risk of heart block.
Nicholas Smedira, MD, MBA:
Mm-hmm.
Juan Pablo Umana, MD:
Correct? Which, again, is very low, but a real one. What would you say that risk is?
Nicholas Smedira, MD, MBA:
So in our experience, my personal experience, if you have a normal EKG coming into the operation, no pre-existing abnormalities on your EKG, the chance of needing a pacemaker, it's very rare. There are some conduction abnormalities that are preexisting that increases, and we have good data on what the risk would be in some patients, if you've had a right bundle branch block, and maybe some percent will need a pacemaker, but it's very low. The other concern would be that you take too much septum and you create a hole or defect in the septum.
Juan Pablo Umana, MD:
Called a ventricular septal defect, right?
Nicholas Smedira, MD, MBA:
Ventricular septal defect caused by shaving too much muscle. And in our experience where we just reviewed about 1,500 of them, we had two. To avoid that, it's understanding the three-dimensional anatomy, having good imaging specialists, and besides that, as you pointed out, it's a very safe and relatively quick operation. We have a number of patients that go home within three days of the surgery.
Juan Pablo Umana, MD:
Yeah, I agree. I think that it's an operation that has way more benefits than risks. Wouldn't you agree?
Nicholas Smedira, MD, MBA:
Without a doubt.
Juan Pablo Umana, MD:
Because it's not only the shortness of breath, but there is a clear risk of sudden death. And that takes us to the other aspects of it is how many of these patients will actually require an implantable defibrillator? That's something that will come up and something that scares a lot of patients. Do drugs, or is it the medical treatment, the pharmacological treatment of the disease, get rid of that risk of sudden death? How do you approach that? Because that's one of the things that I find challenging afterwards when you actually get rid of the obstruction, the patient is feeling fine and they go see their cardiologist and sometimes will recommend that they have an implantable defibrillator.
Nicholas Smedira, MD, MBA:
Yes, a defibrillator, it's a tricky question because the event rate of dropping dead with hypertrophic cardiomyopathy is really, really, really low for all comers, but it's not zero. So we look and have developed a risk calculator to try and identify those patients at highest risk. We have some data that suggests doing the myectomy does seem to reduce the risk of sudden death, probably from getting rid of the obstruction, but it's not strong enough to suggest that if you get a myectomy, you don't necessarily need a defibrillator if the other indications are there.
The predictors, the variables that we use to guide our decision making for a defibrillator are, one, if you ever had an episode yourself of sudden death, then obviously you need a defibrillator. If you have a close relative that's had it, that puts you at risk. So we would recommend if the septum is super-duper thick, over three centimeters, that's a criteria, and we're starting to use the MRI to look for scar, and part of the hypertrophic cardiomyopathy pathology is to get scar tissue in the muscle. And we've identified a scar burden of more than 15% as a predictor, and we put that in, there are actually calculators that are available that you add those variables, and then you come up with a risk score.
It's important, as we mentioned, to have that multimodality team because when there is that concern, I have the patient see our electrophysiologist experts in both, not only the implantable, the traditional ones that go in through the vein, but a whole new generation of subcu defibrillators that don't go through the veins, which may have advantages for somebody that's young is going to have a defibrillator. So that team approach with expertise in these individual areas, the rhythm management, the obstruction management, the surgical management, the drug management, the follow-up, the genetics, all is really critical to get that comprehensive care that one needs when you have this disorder.
Juan Pablo Umana, MD:
I think we can all agree that we have a pretty wonderful team that will be able to help patients and their families with this condition and help guide them in terms of deciding when surgery is needed so that you and I can take care of them and offer them the best possible treatment and cure of the disease.
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