Myocarditis: inflammation of the heart muscle

What it is, in plain words

Myocarditis is inflammation of the heart muscle itself, most often triggered by a virus or by the immune reaction that follows it. The inflamed muscle contracts less well and can generate abnormal rhythms. Most people recover fully, but the recovery phase needs respecting.

Signs to look out for

• Chest pain, often days to weeks after a viral illness
• Unusual breathlessness or fatigue on mild effort
• Palpitations or irregular heartbeat
• Fever, aching muscles, and sometimes fainting
• Signs of heart failure such as ankle swelling in severe cases

Why it happens

Viruses are the leading cause. Others include bacterial infections, autoimmune diseases, certain medicines and immunotherapies, and toxins including cocaine and heavy alcohol use.

How doctors confirm it

Doctors combine an ECG, troponin blood test, echocardiogram and, most usefully, cardiac MRI, which shows inflammation and scarring. Biopsy is reserved for severe or unexplained cases.

Treatments and solutions

• Rest, with complete avoidance of competitive or intense exercise for three to six months, because exertion during active inflammation is dangerous
• Standard heart failure medicines when pumping function is reduced, such as beta-blockers and ACE inhibitors
• Treatment of rhythm problems, with monitoring in hospital when the case is severe
• Immunosuppressive treatment for specific autoimmune forms
• Mechanical support or transplantation in the rare fulminant cases

Living with it day to day

Return to sport only after repeat testing shows normal function, normal troponin and no arrhythmia. Alcohol and stimulants should be avoided during recovery.

When to seek medical help

Seek emergency care for severe chest pain, fainting, very fast or irregular heartbeat, or breathlessness at rest.

This article explains general health information in simple language. It does not replace advice from your own doctor.