The treatment of hypertrophic cardiomyopathy is evolving. Last week, Dr. Nicholas Smedira and Dr. Juan Pablo Umaña provided an overview of surgical myectomy. This week, they talk about testing, medical management vs. surgery, and possible complications after surgery.
The treatment of hypertrophic cardiomyopathy is evolving. Last week, Dr. Nicholas Smedira and Dr. Juan Pablo Umaña provided an overview of surgical myectomy. This week, they talk about testing, medical management vs. surgery, and possible complications after surgery.
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Nicholas Smedira, MD, MBA:
Hi, I'm Nick Smedira and I'm here with Dr. Juan Umaña. We're here to talk about septal myectomy.
Juan Pablo Umaña, MD:
Now, when should a patient actually have surgery? Because 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, I mean mid-60s, who is getting abnormally short of breath, I advise those people to 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:
Right, so I think there's two times that we think about getting a stress test. And a stress test is generally where you put your sneakers on and you get on-
Juan Pablo Umaña, MD:
On a treadmill. 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. But what we do is we put you on the treadmill, a pair of sneakers, we slowly elevate the treadmill. You feel like you're going to go like you know on the Roadrunner things, you go flying into the wall. And then, as soon as you say, "Uncle, I can't do it anymore," we put you on the echo table, turn your sideways and start getting images. And so, 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 on track or lacrosse. It'd be a great thing to just make sure there's no obstruction.
Anybody that comes in with symptoms, say they get short of breath, dizzy, whatever it may be, we'll do the baseline echo. We'll do some, what we call, provocative maneuvers where we have them bear down, that's called a Valsalva. We give them this drug called amyl nitrate, which is a stinky stuff 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 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 of contraction of the heart, and that would typically be a beta blocker.
Juan Pablo Umaña, MD:
And it's important to point out that a good percentage of patients will get better-
Nicholas Smedira, MD, MBA:
With those. Right.
Juan Pablo Umaña, 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 man, so 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, 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, it seems to be very well-tolerated, but it's a lifelong therapy the best we can 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 patient 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's 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 Umaña, MD:
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. And 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 breathe 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 Umaña, MD:
What are the downsides to the operation, aside from the immediate post-operative discomfort and pain? There is a risk of heart block, correct?
Nicholas Smedira, MD, MBA:
Mm-hmm.
Juan Pablo Umaña, MD:
Which is very low, but a real one. What would you say that risk is, Nick?
Nicholas Smedira, MD, MBA:
So, heart block, that is when you need a pacemaker after surgery. 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 we call them conduction abnormalities that are pre-existing, that increases. And we have good data on what the risks would be. The other concern would be that you take too much septum and you create a hole or defect in the septum-
Juan Pablo Umaña, MD:
Oh, the 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 Umaña, 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 Umaña, 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 a preventive treatment for sudden death, meaning an implantable defibrillator? Because that's something that will come up when you look up this disease and something that scares a lot of patients. 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, patient is feeling fine and they go see their cardiologist and sometimes will recommend that they have an implantable defibrillator.
Nicholas Smedira, MD, MBA:
Right. Yes, a defibrillator, it's a tricky question. 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, and 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.
And 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 electrophysiologists, experts in both, not only the implantable, the traditional ones that go in through the vein, but a whole new generation of [subcutaneous] 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. It's an exciting time for hypertrophic cardiomyopathy.
Juan Pablo Umaña, MD:
I look forward to us working together. Thanks very much.
Nicholas Smedira, MD, MBA:
Fantastic.
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