Managing the Most Common Inherited Disease of the Heart Muscle: Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy (HCM) is a genetic disease that causes the heart muscle to become thicker, making it harder for the heart to pump blood. It's a condition that affects one in 200500 people. HCM often goes undiagnosed but is usually discovered during cardiac testing.
With HCM, the patient develops heart failure symptoms, including:
- Chest pain
- Lightheadedness
- Palpitations
- Fatigue
- Shortness of breath
- Fainting
- Peripheral edema
- Abdominal bloating
Up to two-thirds of patients also develop an obstruction of the outlet of the heart.
We call that left ventricular outflow tract obstruction, and it too leads to symptoms of heart failure, explains Alison Brann, MD a cardiologist and HCM specialist at 泫圖弝け of Utah 泫圖弝けs Hypertrophic Cardiomyopathy Program.
DIAGNOSIS AND PREVALENCE
HCM is diagnosed through cardiac imaging. Normal thickness is 10 millimeters or less, but HCM occurs when the heart wall thickening to 13 to 15 millimeters.
When the ventricular wall gets to three centimeters or more, that's very concerning, Brann says. It increases your risk for a dangerous heart rhythm that can lead to sudden death."
This affects 1% of HCM patients.
Clinicians assess several factors to determine risk, such as:
- Family history
- Fainting without explanation
- Heart monitor findings
- Heart muscle measurements
- Amount of cardiac fibrosis
- Heart function status
- Presence of an apical aneurism
Until recently, the only way to screen family members for HCM was through periodic echocardiograms. Today, genetic testing is the standard for families in which a genetic mutation is identified. Hypertrophic cardiomyopathy genetics is also fast evolving. If you had genetic testing more than five years ago and suspect HCM, Brann advises to review the results with your doctor to help determine whether you need to be tested again.
TREATMENT AND MANAGEMENT
There are two types of HCM, which include different treatment and management options:
- Obstructive: The heart wall muscle thickens and blocks or reduces blood flow to the heart. Common symptoms include chest pain and fainting.
- Non-obstructive: The heart wall also thickens, but blood flow is not blocked. Common symptoms include fatigue and fluid retention.
Of the two types of HCM, hypertrophic obstructive cardiomyopathy is easier to manage with:
- Medications (beta blockers, calcium channel blockers, disopyramide or cardiac myosin inhibitors)
- Septal reductive therapies (septal myectomy), which involve surgery
- Catheter-based procedure (alcohol septal ablation)
- Cardiac myosin inhibitors (CMI), FDA-approved in 2022, have shown to be effective in improving obstructive HCM symptoms. They require careful monitoring with frequent clinical visits and echocardiograms to ensure dosing is efficacious and safe.
Treatment for non-obstructive HCM is more challenging.
Non-obstructed HCM requires that we relax the heart, Brann explains. Currently, there are no medications specifically to do that. However, the use of CMIs in non-obstructive HCM is being studied to see if it can help improve symptoms and quality of life for these patients.
In the meantime, diuretics are prescribed to help reduce excessive fluid that comes with non-obstructive HCM, plus medicine to control blood pressure. A heart transplant is also sometimes needed.
Tracking HCM is critical. While an echocardiogram or a cardiac MRI is done initially, an EKG is needed annually. This is repeated every three to five years.
EXERCISE AND SPORTS PARTICIPATION
Early studies suggested that HCM was the most common cause for sudden cardiac death during exercise. As a result, many athletes were disqualified from participating in sports, and patients with HCM were advised against exercising.
We now know that not to be true, and unilaterally disqualifying athletes from play is the wrong approach, says Alan Jacobsen, MBChB a sports cardiologist and HCM specialist at 泫圖弝け of Utah 泫圖弝け.
In fact, over the past two decades have shown that patients with HCM who do not exercise have greater metabolic and cardiovascular disease. Furthermore, has not found a higher risk of sudden cardiac death among individuals who exercise at higher intensities.
Unfortunately, therapies do not prevent all episodes of sudden cardiac death, which can occur when a patient is exercising or resting. But its crucial that athletes and other active individuals are seen by an HCM expert with experience in assessing and minimizing this risk.
Hypertrophic cardiomyopathy is a disease that's managed but not curedat least not yet.
There are ongoing studies looking at gene therapy in HCM, Brann says. If they prove successful, they could potentially lead to a cure.
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