Cardiomyopathy (Heart Muscle Disease)

Types of cardiomyopathy

Strictly speaking, ischemic cardiomyopathy results from another disease, but the term is widely used.

Symptoms

Some people have no symptoms for years. When they appear:

• breathlessness on exertion, then at rest or lying flat
• fatigue and reduced exercise capacity
• swelling of the ankles, legs and belly
• palpitations or a racing, irregular heartbeat
• chest pain, especially in hypertrophic cardiomyopathy
• dizziness or fainting, particularly during exercise
• sudden cardiac arrest, sometimes the first sign in young people

Causes and risk factors

• Family history: many cardiomyopathies are inherited, usually in an autosomal dominant pattern, giving each child a 1 in 2 chance of carrying the variant.
• Coronary artery disease and heart attacks.
• Long-term high blood pressure and heart valve disease.
• Alcohol and stimulant drugs such as cocaine and amphetamines.
• Viral infections causing myocarditis.
• Cancer treatments such as anthracyclines and trastuzumab, and chest radiation.
• Infiltrative diseases: amyloidosis, sarcoidosis, hemochromatosis.
• Endocrine and nutritional problems: thyroid disease, diabetes, thiamine deficiency.
• Prolonged fast heart rhythms (tachycardia-induced cardiomyopathy), which is reversible.

Diagnosis

• Echocardiogram: shows heart size, wall thickness and pumping (ejection fraction).
• ECG: rhythm problems, thick walls, conduction blocks.
• Cardiac MRI: detailed muscle characterization, scar and infiltration.
• Blood tests: BNP or NT-proBNP for heart strain, troponin, thyroid, iron, kidney function.
• Holter monitoring for arrhythmias.
• Coronary angiography or CT to look for coronary disease.
• Genetic testing and family screening: first-degree relatives are offered ECGs and echocardiograms, and gene testing if a variant is found.
• Biopsy or specialized scans for amyloidosis or sarcoidosis.

Treatment

Medicines

• For a weak pumping heart (heart failure with reduced ejection fraction): four core drug groups improve survival: ARNI or ACE inhibitor/ARB, beta-blockers, mineralocorticoid receptor antagonists, and SGLT2 inhibitors. Diuretics relieve fluid buildup.
• For hypertrophic cardiomyopathy: beta-blockers or calcium channel blockers, and cardiac myosin inhibitors (such as mavacamten) for obstructive forms.
• Anticoagulants for atrial fibrillation or clots in the heart.
• Disease-specific drugs: for example tafamidis for transthyretin amyloidosis.

Devices and procedures

• Implantable cardioverter-defibrillator (ICD): shocks the heart out of life-threatening rhythms in people at high risk of sudden death.
• Cardiac resynchronization therapy for weak hearts with a wide QRS.
• Septal myectomy or alcohol septal ablation to relieve obstruction in hypertrophic cardiomyopathy.
• Catheter ablation for some arrhythmias.
• Left ventricular assist devices and heart transplant for advanced disease.

Living with cardiomyopathy

• Limit salt, and follow fluid advice if given.
• Avoid alcohol in alcohol-related or dilated cardiomyopathy, and avoid stimulant drugs.
• Weigh yourself daily to catch fluid buildup early.
• Stay active with a plan agreed with your cardiologist. Many people can exercise safely; guidance on competitive sport has become less restrictive for some conditions after individual assessment.
• Get flu, COVID-19 and pneumococcal vaccines.
• Plan pregnancy with a cardiologist.

Complications

• heart failure
• atrial fibrillation and stroke
• ventricular arrhythmias and sudden cardiac death
• heart valve leaks from an enlarged heart
• blood clots in the heart

Outlook

The outlook varies widely by type and cause. Many people with hypertrophic cardiomyopathy have a normal life expectancy with modern care. Dilated cardiomyopathy often improves substantially with medicines, and some causes, such as alcohol, tachycardia and peripartum cardiomyopathy, can partly or fully reverse. Advanced disease can be life-limiting, but devices and transplant offer options.

Frequently asked questions

What are the first signs of cardiomyopathy?

Early signs include breathlessness with activity, unusual tiredness, swollen ankles, palpitations, dizziness, and chest discomfort. Some people have no symptoms and are diagnosed after an abnormal ECG, family screening, or, rarely, after fainting or cardiac arrest.

What causes cardiomyopathy?

Causes include inherited gene variants, coronary artery disease, long-term high blood pressure, heavy alcohol use, viral infections, some chemotherapy drugs, amyloidosis, pregnancy and thyroid disease. In some people no cause is found.

Can cardiomyopathy be reversed?

Some types can improve or reverse, such as cardiomyopathy caused by alcohol, fast heart rhythms, pregnancy, stress (takotsubo) or thyroid disease. Genetic forms are lifelong but often well controlled with medicines and devices.

What is the life expectancy with cardiomyopathy?

It depends on the type, severity and response to treatment. Many people live normal or near-normal lifespans with modern medicines, devices and monitoring. Advanced heart failure carries a poorer outlook, but transplant and assist devices are options.

Is cardiomyopathy hereditary?

Many forms are, especially hypertrophic, arrhythmogenic and some dilated cardiomyopathies. If you are diagnosed, your parents, siblings and children are usually advised to have heart screening and possibly genetic testing.