Lisa Salberg remembers being in the sixth grade and excelling at athletics. She loved to run and compete with her classmates, finishing near the top in many gym class activities. But by the time the seventh grade rolled around, Salberg had fallen back. She had trouble catching her breath, struggled to keep up with peers and often finished close to last in group runs, even though there was nothing visibly wrong. But under the surface, trouble was brewing. At age 12, after doctors detected a heart murmur during a routine school physical, Salberg was diagnosed with hypertrophic cardiomyopathy—a disease you’ve probably never heard of unless someone in your family has it. In Salberg’s case, many family members did have it—including her father, sister and daughter. After her own stroke at age 21 and losing her 36-year-old sister to cardiac arrest caused by the condition, Salberg decided to take action, forming the Hypertrophic Cardiomyopathy Association, a nonprofit advocacy and resource organization. In recognition of this week’s National Hypertrophic Cardiomyopathy Awareness Day, Salberg says, “It’s a disease that is misunderstood and misdiagnosed. There is a total lack of awareness—and it’s costing lives. People need to know if they’re at risk.”
What is hypertrophic cardiomyopathy?
In a nutshell, hypertrophic cardiomyopathy is a heart muscle disorder in which the walls of the lower heart chambers become abnormally thick (i.e. “hypertrophied”). These thickened heart walls then become stiff, making it difficult to pump blood through the heart or out from the heart efficiently with each heartbeat. The American Heart Association describes HCM as being caused by “abnormal genes in the heart muscle.” So how do these abnormal genes occur in the first place? A brief science lesson: “Every time a cell divides, the genome or the DNA gets duplicated,” explains Ali J. Marian, M.D., director for the Center for Cardiovascular Genetics at the University of Texas Health Science Center in Houston. “The replication process is not perfect, meaning that the machinery that replicates the DNA makes occasional errors. The rate of this error is exceedingly low. However, if the error, which we call a mutation, affects the part of the genome that codes for an important protein in the heart that is responsible for the contraction of the heart muscle, it might lead to HCM.”
Is hypertrophic cardiomyopathy genetic?
Genetics are the leading known cause of hypertrophic cardiomyopathy, and the disease is considered both a genetic and inherited form of heart disease, says Martin S. Maron, M.D., director of the Hypertrophic Cardiomyopathy Center at Tufts Medical Center in Boston, MA. “With HCM, the patient has no choice—they were born with a mutation that put them in position to develop this disease,” he says. The condition is autosomal dominant, says Dr. Maron, which means that a person will likely develop the disease if the gene is passed on from just one parent. Put another way, a parent who has hypertrophic cardiomyopathy has a 50% chance of passing on the genes that cause the condition to their child.
Causes of hypertrophic cardiomyopathy
There isn’t a single gene that determines whether or not someone develops HCM, but rather, multiple genes in which mutations can lead to errors in the process of encoding proteins of the cardiac muscle (also called cardiac sarcomere), says Michelle Kittleson, M.D., Ph.D., director of heart failure research and professor of medicine at the Smidt Heart Institute at Cedars-Sinai in Los Angeles. According to a recent study in the journal Frontiers in Cardiovascular Medicine, HCM may be caused by more than 1,400 mutations in 11 or more genes encoding the proteins of the cardiac sarcomere. “There are at least eight to 12 genes where we know that if you have variance you can develop hypertrophic cardiomyopathy,” agrees Ferhaan Ahmad, M.D., Ph.D., a member of the American Heart Association HCM Initiative Science Advisory Group and the director of the Cardiovascular Genetics Program at the University of Iowa Carver College of Medicine. There are a dozen or so additional genes that scientists believe may be associated with HCM, Dr. Ahmad adds, but so far, the research is not strong enough to confirm. Curiously, though, about half of the people with this disease do not have an identifiable mutation. “There may be a number of reasons for this,” says Dr. Ahmad. “In some cases, there may be certain genes that are associated with HCM that we don’t know about yet.” In other cases, he says, someone may inherit a genetic variant that puts them at risk for HCM, and then encounters an environmental factor that triggers disease development. “For instance, high blood pressure can cause some thickening of heart muscle—so while it might not be the cause of HCM, if someone is predisposed to the condition, it will exacerbate the problem,” he says. “But there is still a lot we don’t know.”
Types of hypertrophic cardiomyopathy
“The two major forms of HCM are obstructive and nonobstructive,” says Dr. Kittleson, who is also on the American College of Cardiology/American Heart Association writing committee for hypertrophic cardiomyopathy guidelines. “Obstructive HCM occurs in about two-third of patients and nonobstructive HCM in one-third of patients.”
Obstructive hypertrophic cardiomyopathy
In obstructive HCM, the wall (also called the septum) between the heart’s lower chambers (known as the right and left ventricles) thickens and stiffens. In some cases, this abnormally thick septum can impede the flow of blood from the left ventricle to the rest body.
Nonobstructive hypertrophic cardiomyopathy
In other cases, the thickening and stiffening of the left ventricle make it difficult for the chamber to fill with enough blood to pump to the rest of the body. This is known as nonobstructive HCM. While blood flow is not impeded in the way it is with the obstructive type of the disease, the end result is the same: weaker blood flow to the rest of the body.
Hypertrophic cardiomyopathy symptoms
While an estimated 700,000 to one million people in the U.S. have HCM, (or one in 200 to 500 people, according to the Hypertrophic Cardiomyopathy Association), only 150,000 of them are being treated for the condition. That’s due to a lack of awareness about the disease, as well as a large segment of people with hypertrophic cardiomyopathy who don’t have symptoms and remain unaware that they have HCM—until a cardiac event like a heart attack. So what should you be on the lookout for? These are some of the most common symptoms of this form of heart disease, according to the American Heart Association:
Abnormal heart rhythms (also known as arrhythmias)Chest pain, especially with physical exertionDizzinessFaintingFatigueLightheadednessShortness of breath, especially with physical exertionSwelling in the ankles, feet, legs, abdomen and veins in the neck
If you’re experiencing any of these symptoms, especially if there is no obvious cause or clear change in your daily activities or behavior, see your doctor. HCM can be diagnosed using your family medical history, a physical exam, and tests like echocardiograms, which measure the thickness of the heart muscle and the amount of blood flow from the heart. Echocardiograms can also help distinguish between the two types of HCM, which is important since treatment will differ depending on your type.
Nonobstructive hypertrophic cardiomyopathy treatment
The range of treatment options for HCM depends of which type you have, and how severe your symptoms are. “About 30% of people with HCM are asymptomatic and don’t require intervention, says Dr. Maron. “Another 50% to 60% of patients do reasonably well on drug therapy.” For people with nonobstructive HCM who have mild symptoms, medications like beta-blockers are frequently used. “Beta-blockers work by slowing down your heart rate and decreasing how hard heart works,” explains Steve R. Ommen, M.D., the medical director of the Mayo Hypertrophic Cardiomyopathy Clinic in Rochester, MN. “Calcium channel blockers may also be used.” In both cases, adds Dr. Ahmad, these medications relax the force of contraction of the heart and lower your heart rate to ease stress on the muscle. If beta-blockers, also known as beta-adrenergic blocking agents, sound familiar, it’s because they are meds frequently prescribed to reduce blood pressure and manage other forms of heart disease. Calcium channel blockers were also designed to lower blood pressure. “The challenge with treating HCM right now is that every drug used was originally designed to treat something else,” says Dr. Ommen. “We’re taking advantage of side properties of these drugs to treat HCM.” Not for long, though: “We are on cusp of new novel drugs—the first drugs to be specifically created for HCM,” says Dr. Ommen. “They are not on the market yet, but when they are approved, they are expected to change our approach to management of HCM in patients.” One such drug, mavacamten, has been shown to be safe and effective at reducing stress on the walls of the heart in studies. It is awaiting FDA approval for both nonobstructive and symptomatic obstructive HCM. The novel therapy, which Dr. Ahmad helped develop, works by reducing the over-activity of proteins that form the heart walls. “It puts the heart in a more relaxed state,” he says.
Obstructive hypertrophic cardiomyopathy treatment
While medication is the primary treatment approach, for people with the obstructive form of HCM who have more serious symptoms of chest discomfort or shortness of breath, surgery or catheter-based ablation of the septum may be recommended. “About 10% to 20% of patients with obstructive HCM will need what’s known as septal reduction therapy,” says Dr. Maron. Septal reduction therapy is a procedure to reduce the thickness of the heart wall separating the two lower chambers. There are two forms of septal reduction therapy: surgical myectomy (an open-heart procedure to shave down the thickness of the septum) or alcohol septal ablation, a noninvasive catheter-based procedure that causes a controlled myocardial infarction in the blood vessel to the septum of the heart so the heart muscle thins. Research suggests the two procedures are equally effective, so which one your doctor suggests will depend of factors like age, general health and personal preference. In addition to these procedures, a patient with arrhythmias, fainting issues or serious lightheadedness during palpitations may receive a defibrillator. And finally, gene therapy or genetic-based correction is a theoretical possibility, says Dr. Marian. “The technology is out there already, referred to as the CRISPR-Cas9 system, but it is not quite efficient yet,” he says, noting that progress continues to be made.
Hypertrophic cardiomyopathy diet
There is no single diet plan that can reduce your odds of getting HCM or directly improve symptoms of the disease. However, the basic tenets of heart health apply, experts agree, including following a heart-healthy diet. This means avoiding high-fat, highly processed foods and sticking to lean protein, fresh fruits and vegetables and complex carbohydrates at most meals. A healthy diet can help you carry a few less pounds—and less strain on your frame can take some pressure off your heart with HCM (and other forms of heart disease).
Hypertrophic cardiomyopathy exercise restrictions
If you’ve heard anything about HCM prior to reading this story, it’s likely in conjunction with rare but highly publicized deaths of young athletes with this disease. (These athletes are unaware they have hypertrophic cardiomyopathy until pushing their bodies to the limit causes sudden cardiac death.) Because of this, in the past, patients with HCM were told to avoid exercise because of this risk, says Dr. Kittleson: “However, it is now known that sudden cardiac death is rare and that regular exercise is safe and important for mental and physical health.” Still, while recreational exercise is recommended to improve cardiovascular health (as with most forms of heart disease, some exercise is better than none) doctors still caution against strenuous exercises such as weightlifting with HCM, says Dr. Marian. “Heavy isometric exercises put an extra burden on the heart muscle and make the muscle thicken,” he explains. The decision to participate in competitive athletics is trickier still, says Dr. Kittleson, and requires a careful discussion with your doctor about the risks and benefits.
Hypertrophic cardiomyopathy life expectancy
Today, with advancements in awareness and treatments for hypertrophic cardiomyopathy, “overall the survival of patients with HCM is comparable to that of the general population and the majority of patients have few symptoms over the course of their lifetime,” says Dr. Kittleson. A meta-analysis of 19 studies on HCM shows that the average five-year survival rate is around 82%, while the 10-year survival rate is closer to 75%. “For those who do progress to have more symptoms with HCM, medications and surgery can improve quality of life,” she adds. The main risk for people with undiagnosed hypertrophic cardiomyopathy is cardiac arrest—the cause of death for Salberg’s sister and countless others. But HCM doesn’t have to be fatal, stresses Salberg, whose organization recognizes 43 Centers of Excellence around the country where doctors specialize in diagnosing and treating the disease. “If you’re having symptoms, get yourself to a cardiologist. If you don’t know your family history, find out,” she says. “We need to raise awareness about this disease, and we need legislative change to improve the path to diagnosis, so families who don’t know HCM is a risk for them can find out.” Up next: How Does the DASH Diet Impact Your Blood Pressure and Weight Loss Goals?
Sources:
Ali J. Marian, M.D., director for the Center for Cardiovascular Genetics at the University of Texas Health Science CenterMartin S. Maron, M.D., director of the Hypertrophic Cardiomyopathy Center at Tufts Medical CenterMichelle Kittleson, M.D., Ph.D., director of heart failure research and professor of medicine at the Smidt Heart Institute at Cedars-SinaiFerhaan Ahmad, M.D., Ph.D., member of the American Heart Association HCM Initiative Science Advisory Group, director of the Cardiovascular Genetics Program at the University of Iowa Carver College of MedicineSteve R. Ommen, M.D., the medical director of the Mayo Hypertrophic Cardiomyopathy Clinic in RochesterAmerican Heart Association: “Hypertrophic Cardiomyopathy.”Genetic and Rare Diseases Information Center/National Institutes of Health: “Familial Hypertrophic Cardiomyopathy.”Mayo Clinic: “Calcium-Channel Blockers.”Mayo Clinic: “Beta Blockers.”Biomolecules: “Hypertrophic Cardiomyopathy: An Overview of Genetics and Management.”Circulation Research: “Hypertrophic Cardiomyopathy: Genetics, Pathogenesis, Clinical Manifestations, Diagnosis, and Therapy.”MedlinePlus: “Autosomal Dominant.”Journal of the American College of Cardiology: “Evaluation of Mavacamten in Symptomatic Patients With Nonobstructive Hypertrophic Cardiomyopathy.”Interactive Cardiovascular and Thoracic Surgery: “Surgical septal myectomy or alcohol septal ablation: which approach offers better outcomes for patients with hypertrophic obstructive cardiomyopathy?”European Cardiology: Hypertrophic Cardiomyopathy in Athletes.”Hypertrophic Cardiomyopathy Association: “Updated Thinking on HCM Genetics.”Frontiers in Cardiovascular Medicine: “Hypertrophic Cardiomyopathy: From Phenotype to Pathogenesis to Treatment.”Nature: “Survival and prognostic factors in hypertrophic cardiomyopathy: a meta-analysis.”
