Hypertrophic Cardiomyopathy (HCM) is a heart condition where the heart muscle becomes abnormally thick, making it harder for the heart to pump blood. For many, it goes unnoticed—until symptoms suddenly appear or complications arise.
Your heart’s job is simple: it pumps blood without oxygen (deoxygenated) to your lungs to collect oxygen, and then pumps oxygen-rich blood out to the rest of your body.
Hypertrophic Cardiomyopathy (HCM) is a condition where the heart muscle becomes thicker than normal. The heart’s job is to pump oxygen-rich blood to the body, but when the muscle wall is thick and stiff, it’s harder for blood to fill the heart and flow out properly.
The 1995 CARDIA study, a multicenter, US-population-based echocardiography study of 4111 subjects (aged 23-35), identified the prevalence of HCM as 1:500 people in the general population. The 2015 Semsarian publication identified that the prevalence of HCM gene carriers could be as high as 1:200.
Estimated undiagnosed range calculated using prevalence of 1:500, estimated US population (332,330,571 in May 2021), and estimated diagnosed population (~100,000).
• The muscle cells in the heart are not lined up normally (this is called myocardial disarray).
• Even mild thickening can cause symptoms because the heart becomes stiff.
• The heart has to work harder to pump blood, which may lead to fatigue, chest pain, or a fast heartbeat.
People with HCM may not always notice sudden changes. Instead, symptoms build slowly over time, so they may feel “normal.” Common experiences include:
• Unexplained tiredness or short of breath
• Chest pain or palpitations (fast or irregular heartbeat)
• Dizziness or fainting
• Always feeling slower or less energetic than friends
• Not being able to keep up in sports or activities
These symptoms are important—don’t ignore them.
The goal is simple: help you feel better, live fully, and reduce risks.
Depending on your condition, doctors may suggest:
Your doctor may look for HCM if:
• Someone in your family has HCM
• You have symptoms such as a heart murmur
• Tests like an ECG or Echo show your heart isn’t working normally
The doctor will ask about:
• Your family’s heart health
• Your own heart health
To make a diagnosis, doctors need to see how your heart looks and works. They may do:
• Echocardiogram (Echo): An ultrasound that shows the heart’s walls and blood flow
• MRI: Gives a detailed picture if the echo is not clear enough
• Genetic testing or family history check: Helps when images are unclear but HCM is suspected
• HCM is genetic (runs in families).
• It can affect anyone—men or women, young or old, any ethnicity.
HCM causes the heart muscle to become thick in some parts, develop scarring, and stiffen up. These changes can cause issues with blood flow and conduction of the electrical signals that make the heart beat in a regular rhythm. Not every HCM heart is impacted the same way; in fact, there is a great degree of variability in the HCM heart.
Think of your heart like a house.
What are two types of HCM?
What Happens in HCM Obstruction
In hypertrophic cardiomyopathy (HCM), the wall of the heart (especially the septum, the wall between the left and right lower chambers) becomes thicker than normal. Because of this:
This blockage (called obstruction) means blood has a harder time leaving the heart. Pressure builds up inside the heart, and the heart has to work extra hard to pump.
Imagine squeezing the end of a garden hose with your thumb. Less water comes out, but it comes out faster, and the pressure builds up inside. In HCM, the thickened wall makes the “exit” narrow, so less blood leaves the heart with each beat, and pressure builds inside.
In some people, the mitral valve doesn’t close properly and instead moves into the pathway, blocking blood flow. This can also cause blood to leak backward into the left atrium (mitral regurgitation), which may lead to irregular heart rhythms like atrial fibrillation.
Doctors measure the “pressure difference” (gradient) between the inside of your left ventricle and the aorta (the main artery).
• A gradient under 30 mmHg is usually not considered obstruction.
• Gradients can be fixed (always there) or provocable (showing up with exercise).
• Echocardiograms and stress echocardiograms help measure this.
Hypertrophic cardiomyopathy (HCM) can be hard to detect. Its symptoms are different for each person, and many of them overlap with other, more common conditions. Sometimes the signs feel mild or temporary, so doctors may not suspect HCM right away unless detailed heart tests are done.
If someone in your family is diagnosed with hypertrophic cardiomyopathy (HCM), or passes away because of it, close blood relatives need to be checked. Screening should include:
Start with your first-degree relatives:
Relatives like aunts, uncles, and cousins (second-degree) should also be told, so they can discuss screening with their doctor. HCM sometimes “skips a generation” because not everyone who carries the gene shows symptoms.
If no genetic test is available (or if no mutation is found):
If a genetic test finds a mutation in the family:
Not everyone with hypertrophic cardiomyopathy (HCM) has the same problems. Some people have no symptoms, while others may need treatment. Your treatment depends on factors like your heart’s structure, scarring, family history, and whether you have rhythm problems (arrhythmias). Many people live normal lives with little or no treatment, but others may need medicines or procedures.
For most patients, medicines are the first step.
• Beta-blockers and calcium channel blockers: slow the heart, let it relax, and pump more oxygen-rich blood with each beat.
• Other medicines: sodium channel blockers, diuretics, blood thinners, or myosin inhibitors may be used depending on symptoms.
If symptoms continue despite medicines, or if obstruction is severe:
• Septal myectomy: an open-heart surgery that removes extra thickened muscle from the septum.
• Often called the “gold standard” treatment, it provides fast and lasting relief.
• If the mitral valve is part of the problem, it can also be repaired or replaced during the same surgery.
For some patients, a less invasive option is available:
• A catheter is inserted through the groin into a small artery of the heart.
• A tiny amount of alcohol is delivered to shrink part of the thickened septum.
• Symptoms improve gradually as the tissue shrinks.
• Recovery is usually quicker than open-heart surgery, though the risk of complications is slightly higher and success rates can be lower.
• ASA is often chosen when patients are too frail for surgery.
HCM can cause irregular heartbeats (arrhythmias). These may be harmless or serious.
• Tests: ECG, Holter monitor, event recorder, or an implantable loop recorder help diagnose arrhythmias.
• Treatment options depend on the type:
Hypertrophic cardiomyopathy (HCM) is often linked to changes (mutations) in certain genes. That’s why doctors recommend genetic testing if you are diagnosed.
In short: genetic testing may not always give answers, but it is an important step for your family’s health now, and for future treatment options.
References:
Living with HCM can feel overwhelming at first. But with the right knowledge, support, and treatment, life can still be rich, active, and meaningful.
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This disease awareness initiative is brought to you by Heart Health India Foundation (HHIF)
Supported by Bristol Myers Squibb (BMS)
Disclaimer: This information is for awareness purposes only. It is not a substitute for medical advice, diagnosis, or treatment. If you have symptoms, concerns, or questions about hypertrophic cardiomyopathy (HCM), please consult a qualified cardiologist or healthcare professional for personalized medical guidance.
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