Myocarditis: symptoms, causes, diagnosis, treatment and recovery

The BHF says people with myocarditis can get chest pain and feel breathless, and it is not unusual for symptoms to start up to two weeks after being unwell with an infection. Common symptoms include:

• Chest pain or discomfort, or a feeling of tightness in the chest.

• Shortness of breath, at rest or when active, or in certain positions such as lying down.

• Unusual tiredness.

• Palpitations (like your heart is fluttering, racing or pounding) or an irregular heartbeat.

• Feeling light-headed or fainting.

• Flu-like symptoms such as a high temperature, headaches, body aches, joint pain or sore throat.

• Rarely, swelling in the hands, legs, ankles or feet.

The BHF says it is common to feel tightness or squeezing in the chest, at rest or when active, or lying down. The pain may be sharp or stabbing and can spread to other parts of the body. If the lining of the heart is also inflamed, the pain may feel better when you lean forward and worse when you lie back.

The BHF says some symptoms of myocarditis are like heart attack symptoms. If you have unexplained chest pain and/or shortness of breath, seek emergency medical help. Call 999 immediately if:

• Your chest pain makes your chest feel tight or heavy.

• Your chest pain lasts more than 15 minutes.

• Your pain spreads to the arms, back, neck and jaw.

• You also feel short of breath and/or feel sick.

The BHF says myocarditis is a disease that causes inflammation of the heart muscle. It can develop suddenly (acutely), recur or be long-lasting (chronic). Cardiomyopathy UK says it can affect the function of the heart and the normal electrical signalling of the heart, and can cause dilated cardiomyopathy in some people.

The BHF says it can happen together with pericarditis (inflammation of the lining around the heart), which has similar symptoms, sometimes called myopericarditis. The NHS describes pericarditis as inflammation of the lining around the heart that causes sharp, stabbing chest pain which often follows a viral infection.

The BHF says myocarditis can affect anyone of any age but tends to affect more males than females, and people under 50.

The BHF says myocarditis is most commonly caused by a virus, such as flu or Covid-19, or another viral infection. When caused by a virus, symptoms can start one or two weeks later because the immune system overreacts to the infection and causes inflammation that can stay in the heart even after the virus has gone.

Other causes listed by the BHF include:

• Bacterial infections, such as a sore throat or chest infection, or fungal infections.

• Autoimmune diseases, such as lupus.

• Harmful substances such as carbon monoxide, or drugs such as cocaine.

• A reaction to certain medicines or vaccines. The BHF says there have been rare cases of myocarditis following the Moderna Covid vaccine, or even more rarely the Pfizer vaccine.

The BHF says your doctor will examine you and ask about recent illnesses, autoimmune problems, exposure to toxins or drugs and other risk factors, for example if you have recently had a baby.

Tests may include an ECG, an echocardiogram, a chest X-ray and blood tests. Other tests such as cardiac MRI and coronary angiogram may be done to help rule out other common cardiac causes. In very rare cases a heart biopsy may be considered.

Cardiomyopathy UK lists blood tests to look for inflammation, infection and heart muscle damage, an ECG to check for abnormal rhythms, and a physical exam and medical history.

The BHF says treatment depends on your symptoms and the cause. It can include painkillers for the chest pain, medicines to calm the inflammation, antibiotics if a bacterial infection is the cause, rest, plenty of fluids and general remedies.

Cardiomyopathy UK says as myocarditis can get better in some cases, not everyone will need treatment. Treatment may be given for the cause (for example, drugs that affect the immune system), for non-heart symptoms such as a high temperature (over-the-counter painkillers), and for symptoms affecting the heart, which usually involves treatment for heart failure with medication.

The BHF says most people will recover without any lasting effects. In rare cases, if inflammation is severe, myocarditis can scar the heart muscle, which makes the heart work harder; the heart muscle can become bigger and, over time, weaker. Sometimes it affects the heart's electrical system and leads to an irregular heartbeat.

It says most people will have one episode of myocarditis and will get better with rest, medicine and avoiding high-intensity exercise while the heart recovers. Doctors will follow your progress closely at first and you may then be offered a yearly follow-up. If the heart is damaged, follow-up is at least every few months.

If your symptoms return, the BHF says to see a doctor straightaway or phone 111.

The BHF says you will need time to rest and recover, and to talk to your doctor about how long to rest before restarting exercise and which types are safe. It says generally it is recommended to avoid vigorous exercise for 3 to 6 months after you are diagnosed with myocarditis.

For work, you may need time off depending on symptoms and your job, and you can get a fit note from your GP. The BHF suggests pillows to get comfortable, light loose clothes, staying hydrated and a healthy diet.

The BHF says if you think you have symptoms of myocarditis, contact your doctor straight away or call NHS 111. Getting diagnosed and treated early can help you feel better and lower your risk of long-term complications.

Call 999 for the emergency signs listed above, and do not drive yourself to hospital.

On the NHS, suspected myocarditis is assessed urgently through your GP, NHS 111 or emergency services, with cardiology follow-up for scans and monitoring. Private cardiology and cardiac MRI are available, and any results should be shared with your NHS team so exercise advice and follow-up stay consistent.