Dr. Mike Smith (Host): Welcome to Pediatrics in Practice, a CME podcast. I'm Dr. Mike. And joining me today is Dr. Brian Birnbaum from Children's Mercy. And today, we'll dive into an important topic, cardiomyopathy in children, what pediatricians need to know. Dr. Birnbaum, welcome to the show. To start off, how do cardiomyopathies differ in adults versus kids and why is it important for general pediatricians to kind of think about these differences?

Dr. Brian Birnbaum: Yeah. Thanks for having me, Mike. So, cardiomyopathies in kids, I think, the biggest difference is the presentation as well as the underlying cause. In adults, a lot of cardiomyopathies are caused by ischemic heart disease and develop over time. In kids, the issue really is that it can develop a little bit more rapidly, or at least the symptoms can come about more rapidly than what we see in adults.

One of the really important things to realize when we talk about cardiomyopathies is that there are a lot of different cardiomyopathies, or I really think of it as three different cardiomyopathies. And because of that, the symptoms differ between the three cardiomyopathies, and the presentation differs between kids and adults for each of those three cardiomyopathies as well.

Host: I want to get into some of the early signs of cardiomyopathy in kids. But before we do that, you know, since you mentioned there's different types of myopathies here, cardiomyopathies, how do you explain each one of those three to patients and parents?

Dr. Brian Birnbaum: Yeah. So really, it's based upon which one of those cardiomyopathies the child has or which one of those cardiomyopathies is present in the family that we're screening for. And so, when we think about it, really, there's dilated cardiomyopathy, which means the heart is enlarged and not squeezing well. There's hypertrophic cardiomyopathy, which means that the heart is really thick, and sometimes squeezing too well and blocking that blood flow coming out of the left ventricle. And then, there's restrictive cardiomyopathy, which I usually think of as more of an issue of getting the blood in to the pump. So, you have a pump and the pump isn't working, not because it can't effectively pump blood out, but because it can't get blood in the way that it's supposed to. And so, I tried to explain based upon which of those cardiomyopathies the patient or the family has, what symptoms, and what signs the patient needs to look for.

Host: Do you use a lot of pictures and images to help you explain this to parents?

Dr. Brian Birnbaum: Yeah. We do typically try to show them a diagram of a normal heart or a model of a normal heart, and then a model of their child's heart so they have some idea of kind of what's different about their child's heart and what we're trying to help prevent from progressing or worsening, or what we're trying to treat sometimes with surgery, for example.

Host: What are some of the early signs or red flags of cardiomyopathy that pediatricians might notice in primary care settings?

Dr. Brian Birnbaum: Yeah. So, I think the most important sign to look for, which is possibly present in all three of those cardiomyopathies, would be syncope or near-syncope. And it presents for different reasons in each of those cardiomyopathies, but it's often related to an arrhythmia that can be present in those cardiomyopathies. So, patients who have syncope, especially with exertion, it's going to be something that we're going to want to hear about or have referred to cardiology, because that's a definite red flag for us.

For our dilated cardiomyopathy patients, a lot of times if they're not presenting with syncope, in fact more frequently, they're not presenting with syncope, but rather they're presenting with fatigue and tiredness and really not keeping up with their peers. And I usually try to explain that to parents that your child is sort of falling off from where they were at. A lot of children, you know, they'll have good days or bad days, and there's always kids that are faster and there's kids that are slower. But if you see where your child typically falls in a group of children, and all of a sudden they're starting to fall behind, that's when we start getting more worried about something like dilated cardiomyopathy where maybe their heart's not efficient enough at pumping blood.

For the hypertrophic cardiomyopathy patients, again, arrhythmias and syncope are one of the bigger presenting signs. But a lot of those patients are generally healthy. And if they're not having syncope—or chest pain is another not uncommon presentation—they're often presenting with a heart murmur that's appreciated by the pediatrician, and it's usually a very harsh systolic ejection murmur. And so, you know, if there's a change in that murmur, especially, we'd want to have that patient seen by cardiology and evaluated by cardiology.

And then, our restrictive patients are actually one of the tougher groups. They tend to be a little bit slower in terms of their presentation and much more gradual in terms of developing symptoms. Often they'll be a little bit more fatigued or a little bit more tired with activity than what they had been. But again, it's very, very gradual. Many of those patients do develop a wet cough that comes from basically those pressures that are elevating in their left ventricle and their left atrium transmitting back to the lungs and causing some component of pulmonary edema.

Host: Are there specific symptoms of pediatric cardiomyopathy that are often subtle? Like you've mentioned, the murmur getting worse, syncope—those aren't that subtle. But are there some things that maybe the primary care doctor's not going to recognize right away as a potential cardiomyopathy?

Dr. Brian Birnbaum: Absolutely, and especially when we talk about fatigue and that tiredness component, that's something that a lot of families don't recognize when it initially starts. And it happens over time, or the pediatrician may not recognize it over time. The other real subtle signs I would say would be the heart sounds during the physical examination, which I think it's really hard for a pediatrician in the office to have a real clean examination sometimes, or a real clear examination when you're listening for very subtle changes such as a sharp S2 that occurs with restrictive cardiomyopathy, for example, or occasionally a gallop that'll occur with the dilated cardiomyopathy patients.

So, a lot of times there are things that are much more subtle. And it comes down to sort of putting the whole picture together, and realizing when you have a patient that maybe is a little bit more tired, that their parents are noticing things, maybe has that new murmur, and just having a high index of suspicion that cardiomyopathy could be one of the causes.

Host: You mentioned before that in children, you know, symptoms tend to develop or they'll present with symptoms a lot sooner than, say, adults with cardiomyopathy. What kind of timeframe are we talking about here between the development of a cardiomyopathy and symptom presentation?

Dr. Brian Birnbaum: So, that can really be anywhere from days to years. What's really, I think, difficult with kids is, in terms of diagnosing cardiomyopathies, is that they're so resilient and they work so hard and they will do everything they can to keep up with their friends. And so, a lot of times they are able to minimize their symptoms or they're able to kind of push beyond what they were normally doing before to keep up with their friends. It's not uncommon that our patients are first diagnosed with a cardiomyopathy when something—what we call—tips them over. And so, in our babies, a lot of times that's, for example, a viral infection. So, they'll have a dilated cardiomyopathy and they do great for months or years, and then they get a viral infection and they just can't keep up after getting that viral infection. So, a lot of times it is a matter of when you're asking your body to do more than it's previously capable of doing.

Host: Now, when should a pediatrician consider further workup versus, say, referral to a specialist like you? And when you do see the patient, what are going to be some of those initial tests you might perform?

Dr. Brian Birnbaum: Yeah. So, I think it's is very nuanced in terms of whether to a workup or refer to cardiology, and it's really never wrong to refer to cardiology. We, on the cardiology side, certainly any patient where there's a strong family history or any of those more concerning symptoms such as syncope or chest pain, would want to see those patients and rule out cardiomyopathies in them.

But for patients that maybe the symptoms are a little bit more subtle and they have a little bit more fatigue that, say, it could be related to a cardiomyopathy or it could be related to some other cause, I think that those are times that continuing the workup as a pediatrician with basic lab work. And we usually think of as looking at end-organ function, a BMP, LFTs, you know, CBC to make sure that they're not anemic as a cause. And then, adding on an NT‑proBNP or a BNP, that's B-type natriuretic peptide, can be helpful in kind of delineating could there be a cardiomyopathy or a cardiac cause to their symptomatology.

Host: What about genetic testing? How has that changed things for you?

Dr. Brian Birnbaum: I'll tell you, genetic testing's been an absolute game-changer, and we're still a lot about how best to utilize it, and it's definitely a moving target. The tough thing with genetic testing is that it's not perfect if you don't have a gene identified in the family.

So in our patients who don't have any family history of a cardiomyopathy, who have a definitive cardiomyopathy themselves, only around 50-60% of them will have a gene that we're able to identify. And what that means is that if we don't have that gene identified in somebody beforehand, and a patient comes in or you're screening a family member and they test negative, you may not know whether or not they have the disease or have that gene or whether you just have a false negative because we don't have all the answers when it comes to genetic testing.

The genetic testing, the other thing that's really interesting about it is that I mentioned that there's really three types of cardiomyopathies that we look at. And sometimes the genes that cause one cardiomyopathy in one person in the family can cause a different cardiomyopathy in a different person in the family.

So, we're still learning a lot more about how these genes function. And so, we have some patients that will have a parent that was a hypertrophic cardiomyopathy patient. And the patient themselves is a dilated cardiomyopathy patient. And that doesn't even get into kind of some of the other genetic syndromes that go with cardiomyopathy, such as Noonan syndrome or genes such as that.

Host: It is fascinating, isn't it? And I think we're learning more and more just about how personalized disease is you could take the same gene in two patients, you have a cardiomyopathy, but that cardiomyopathy can act very differently in those two individuals. So, learning not just the genetics or the genes involved, but those subtle changes in those genes, how they can actually impact, diagnosis, prognosis, treatment, all that. It's absolutely fascinating. And I'm sure, like me, you're excited to see where all this is going to go.

Dr. Brian Birnbaum: It is very exciting. And, you know, the other component to the genetic testing, which really hasn't made its way quite down yet to more the typical genes that cause those cardiomyopathies in kids, would be genetic therapies and gene therapies themselves specifically; looking at, for example, the Duchenne muscular dystrophy population where there's gene therapy that's available. We very well could have gene therapies coming down the line to treat some of these cardiomyopathies in the future.

Host: Absolutely fascinating. I'm going to ask you again about kind of what advances you're interested in. But before we do that, I do want to ask about lifestyle, environmental factors. How do they influence cardiomyopathies in kids?

Dr. Brian Birnbaum: I think the biggest challenge with lifestyle factors in kids with cardiomyopathy actually has been something that we, as medical professionals, maybe didn't do a great job of previously. And that is that we're very risk-averse. And some people still are very risk-averse and have promoted sort of a sedentary lifestyle because of the risk of sudden cardiac death in many of these cardiomyopathies. And I think we've hopefully swung the pendulum a little bit to where we want to encourage at least moderate physical activity in most cardiomyopathies.

There are certainly a subgroup of patients that are at high-risk of sudden cardiac arrest with physical exertion, but that's not the majority of patients. And we've had a lot of patients, I think, unfortunately, that we've restricted from physical activity over the years, that now we're seeing those health problems as adults that come with restricted physical activity and have obesity and have coronary artery disease, when they probably didn't need to be restricted.

Host: Yeah. It's a tough one, right? There's that blanket statement of, you know, limit your activity in these cardiomyopathies. But at the same time, it just doesn't sound right to tell somebody not to get some exercise here and there, you know. But I understand there's some cases definitely, right? And you mentioned that. But I'm glad to hear that you're realizing many cases, they can have some moderate exercise, because that just makes sense to me.

Dr. Brian Birnbaum: Yeah. And, you know, there's so many benefits to exercise beyond the cardiovascular system. Our patients are much happier when they're able to do more activities. Their mental health is much better. Their pulmonary health is much better. They tend to eat healthier when they're more physically active. So, it really is something that we need to focus on, promoting reasonable physical activity for these patients, even if they do have a risk of adverse events with their cardiomyopathy.

Host: Looking ahead, and we kind of touched a little bit on advances, what other advances in treatment or long-term management are you most excited about?

Dr. Brian Birnbaum: We mentioned the gene therapies that are hopefully coming down the line and some of them have reached patients with certain, you know, very specific cardiomyopathies or very specific genetic disorders. One of the things that we find really exciting in the pediatric world and the adult world is about 25 to 30 years ahead of us on is devices, and specifically ventricular assistive devices. These are devices that basically help the heart pump blood out. Sometimes they take over almost entirely for the heart in terms of pumping blood out to the body. But the durable devices that are available, which again are mostly for adults, but we've had children as small as about 25 kilograms at our institution with one of these devices able to be outpatient and able to go to school and do things at home.

And so, having these technological advances to help support patients if they're awaiting a heart transplant, for example, is really exciting, and it has been a game-changer. It's great to be able to have some of these devices available where kids can get out of the hospital as opposed to being in the hospital for months at a time.

Host: Yeah. And you have to assume that the research is probably showing these devices are going to get smaller, better, more efficient, longer lasting, all that kind of stuff, right?

Dr. Brian Birnbaum: I think what's been really great is the devices. Even the devices that are available as we've gone through the years, we're finding out ways to minimize the complications with them. And that's been a game-changer as well, that we're able to prevent bleeding, prevent strokes, and still have patients supported well with these devices.

Host: Last question for you, when you look at all the advances that you've probably seen in your career, from diagnosis to treatment to long-term management, what kind of impact has innovation made on outcome?

Dr. Brian Birnbaum: I think it's been amazing what we've been able to accomplish the last several decades in the world of cardiomyopathy. And being able to identify patients that are higher risk through the testing that we have, the genetic testing that we have, being able to screen families, even if the genetic testing is negative, be able to screen families with ultrasound and echocardiograms and be able to guide families in terms of what patients can do, what their children can do. That sort of day-to-day stuff, I think, has been phenomenal, in addition to those bigger advances such as the devices that we talked about and being able to support children and young adults for a longer period of time while awaiting heart transplant.

Host: Yeah. Dr. Brian Birnbaum, this has been fantastic information. Thank you so much for coming on today and the work that you are doing. For more information, you can visit ckc.link/cmepodcast. If you enjoyed this podcast, please share it and explore the entire library for more topics. This is Pediatrics in Practice, a CME podcast. I'm Dr. Mike. Thanks for listening.