Myocarditis

Some symptoms of myocarditis present like heart attack symptoms and may indicate that you need emergency treatment. Call 999 immediately if you experience the following symptoms, especially in combination:

• Chest pain that lasts more than 15 minutes
• Chest pain that spreads to the arms, back, neck and jaw
• Severe difficulty breathing or nausea

What is myocarditis?

Myocarditis is a condition that inflames the heart muscle (myocardium). It can develop suddenly (acute myocarditis) or it can be recurring or long-lasting (chronic myocarditis). The condition isn't affected by lifestyle, and it can't be prevented. 

Many people recover from myocarditis without any lasting effects. Yet in rare cases, severe inflammation scars the heart muscle. This can cause the heart muscle to become larger, weaker and less capable of effectively pumping blood around the body (known as heart failure).

Myocarditis can also affect your heart's electrical system, leading to an irregular heart rhythm (cardiac arrythmia). Both heart failure and heart arrythmias make you more susceptible to blood clots forming in your heart, which could lead to a stroke or heart attack. 

What causes myocarditis?

Viral infections are the most common cause of myocarditis. The immune system can overreact to viral infections causing excessive inflammation. When viruses cause myocarditis, symptoms can present one or two weeks after the infection, as the inflammation is present even when the virus has already gone. Many viruses have been linked to myocarditis, among them the virus that causes the common cold (adenovirus), hepatitis B and C and COVID-19. 

Other causes of myocarditis include:

• Bacterial infections, such as sore throats and chest infections
• Fungal infections, such as athlete's foot or yeast infections
• Parasitic infections, such as toxoplasma (found in cat faeces)
• Auto-immune diseases, (when your immune system attacks your organs) such as lupus and sarcoidosis
• Medications, including medications for seizures, antibiotics such as penicillin, and antidepressants and other psychiatric drugs
• Cancer treatments, including some chemotherapy agents and radiotherapy
• Harmful substances (toxins), such as carbon monoxide
• Illegal drugs, like cocaine

However, it isn't always possible to confirm the exact cause of myocarditis. In this case, it's referred to as 'idiopathic' myocarditis. 

How is myocarditis diagnosed?

At your initial consultant appointment, we'll discuss your symptoms with you, take your medical history and conduct a physical examination. You may be asked to take some of the following tests to help make a diagnosis:

• Blood tests, which might show the presence of inflammation, infection or damage to the heart muscle
• An electrocardiogram (ECG), which can show abnormal heart rhythms
• An echocardiogram, a type of ultrasound scan that can show muscle damage
• A cardiac MRI (magnetic resonance imaging), which can detect inflammation and scar tissue in the heart muscle
• A FDG PET scan, which uses radioactive dyes to show evidence of inflammation

Your consultant will recommend a treatment plan based on the results of any tests you receive.

The symptoms of myocarditis often resolve on their own, so treatment isn't always needed. Possible treatments could include:

• Painkillers and anti-inflammatory medications
• Over-the-counter medications to help manage non-heart related symptoms such as a high temperature 
• General remedies, such as rest and plenty of fluids

If the cause of your myocarditis is known, your consultant might prescribe a more specific treatment to address it. For example, they could prescribe antibiotics if your myocarditis is caused by a bacterial infection.

Myocarditis medication

If your myocarditis has caused extensive heart muscle and tissue damage, your treatment may involve medication to prevent or manage heart failure. Depending on the severity of symptoms, your consultant might suggest the following:

• ACE (angiotensin-converting enzyme) inhibitors help lower blood pressure, so your heart doesn't have to work as hard.
• ARBs (angiotensin receptor blockers) are used when ACE inhibitors aren't suitable due to side effects.
• ARNIs (angiotensin receptor-neprilysin inhibitors) are like ACE inhibitors and ARBs but stronger.
• Anticoagulants help prevent blood clots from forming.
• Beta blockers slow down your heart rate, improve arrhythmias and help remodel the heart muscle.
• Corticosteroids can help reduce inflammation in the heart muscle.
• Diuretics (water tablets) help decrease water retention, which can occur when the heart muscle weakens.
• Mineralocorticoid inhibitors help improve pumping function and reduce water retention. 
• SGLT2 inhibitors are diabetes medication that has been shown to improve outcomes for patients with heart failure. 

Cardiac devices

When myocarditis has caused severe heart failure, it might be necessary to use medical devices to help your heart function. Devices your consultant might recommend include:

• Pacemakers – Surgically implanted devices that monitor your heart rate for abnormal rhythms. They deliver low-energy electrical pulses that ensure your heart beats at a steady pace, improving the pumping function of the heart.
• Implantable cardioverter defibrillators (ICDs) – Surgically implanted devices that function similarly to a pacemaker but can deliver a shock if they detect your heart beating with a dangerous rhythm.
• Ventricular assist devices (VADs) – Artificial pumps that help the heart pump blood around the body from the lower chambers (ventricles) of the heart.

Myocarditis surgery

In rare cases, the heart failure caused by myocarditis may be so severe that it can't be treated with medication or devices. A heart transplant could be the most effective treatment in this case. This procedure involves removing the failing heart and replacing it with a heart from a donor. 

Our survival rate for all cardiac surgery between 2021 and 2023 was 99.6%.