Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a condition in which the muscular wall of the heart (myocardium) becomes thicker than normal. This caused by mutation of genes coding for the component proteins of the heart muscle. This thickening can make the heart muscle stiff, meaning the heart may not relax or pump blood as efficiently as it should.

The degree of thickening and the areas of the heart affected vary from person to person. The left ventricle (the heart’s main pumping chamber) is almost always involved. The septum (the wall separating the left and right sides of the heart) may also become thickened.

HCM is usually an inherited (genetic) condition caused by a change (mutation) in one or more genes. If a parent has HCM, each child has a 50% chance of inheriting the condition.
It is estimated that HCM affects between 1 in 250 and 1 in 500 people.

Types of HCM

• Obstructive HCM means that the thickened heart muscle partly blocks the flow of blood leaving the heart. This can place extra strain on the heart and may lead to additional issues such as abnormal heart rhythms (arrhythmias) or leakage of the heart valve (mitral regurgitation).
• Non‑obstructive HCM means that although the heart muscle is thickened, it does not significantly block blood flow out of the heart.

Many people with HCM have no symptoms or remain stable throughout their lives. When symptoms do occur, they commonly include:

• Shortness of breath
• Chest pain
• Palpitations (feeling your heart racing, fluttering, or pounding)
• Lightheaded-ness or unexplained fainting spells
• Fatigue (gets tired easily)
• Swelling of the legs, feet, ankles, or abdomen
• Sudden cardiac arrest

Some people may develop symptoms, or notice their symptoms worsening, later in life. This can occur if the heart muscle gradually becomes stiffer over time. The type and severity of symptoms vary depending on how much the heart muscle has thickened and which areas of the heart are affected.

If you have HCM, you may be at higher risk of developing other heart‑related complications. These may include:

• Abnormal heart rhythms (arrhythmias) such as atrial fibrillation or heart block.
• A rare risk of dangerous, life‑threatening arrhythmias that can lead to cardiac arrest and sudden death. This is why identifying people with HCM is so important - early diagnosis allows treatment to reduce this risk.
• A “leaky” heart valve (mitral regurgitation), where the mitral valve does not close properly, allowing some blood to flow backward instead of forward.

Several tests may be used to evaluate your heart:

• Physical assessment – listening to your heart and lungs, checking blood pressure and pulse, and reviewing your medical history
• ECG (electrocardiogram) – records the heart’s rhythm and electrical activity
• Echocardiogram – an ultrasound scan that shows heart structure and function

Panel A: Echocardiogram of a normal heart, showing normal thickness of the left ventricular (LV) walls

Panel B: Echocardiogram of a patient with hypertrophic cardiomyopathy, showing markedly thickened LV walls (red arrows)

• Exercise test – ECG monitoring during physical activity
• MRI scan – provides detailed images of the heart

Genetic Testing

HCM is most often an inherited heart condition, which means it can run in families. If your healthcare professional thinks you might have HCM, you may be offered genetic testing to look for a specific gene change.

If a gene variant is found, your doctor may encourage you to share this information with close family members -such as parents, brothers, sisters, or children - because they may also carry the same gene change.

For anyone who has a parent, sibling, or child with HCM, it is recommended to visit a specialist inherited cardiac conditions clinic. There, they can receive a thorough assessment and discuss options for genetic testing and heart screening. Early identification allows families to get the right support, monitoring, and treatment if needed.

The Cardiomyopathy Clinic at the National University Heart Centre, Singapore (NUHCS) provides a comprehensive evaluation and treatment service for patients with HCM.

While there is currently no cure for HCM, the good news is that many effective treatments are available to help manage symptoms, protect your heart, and support a full, active life. Your care team will tailor a treatment plan specifically for you, based on how your heart is affected and the symptoms you experience.

• Medications such as beta blockers, diuretics, or cardiac myosin inhibitors. These can help your heart work more efficiently, control blood pressure, regulate heart rhythm, and ease symptoms so you feel better day‑to‑day.
• An Implantable Cardioverter Defibrillator (ICD) if you are at higher risk of dangerous heart rhythms. An ICD provides strong protection by detecting and treating these rhythms automatically.
• Permanent pacemaker implantation to help maintain a steady, reliable heart rate if needed.
• Catheter ablation to treat certain abnormal heart rhythms and improve symptoms.
• Septal myectomy, a surgical procedure that removes part of the thickened heart muscle and can significantly improve symptoms and quality of life.