Endocarditis is a rare and potentially fatal type of heart infection.

It's specifically an infection of the inner lining of the heart (the endocardium), most commonly caused by bacteria entering the blood and travelling to the heart.

The heart is well protected against infection and bacteria usually pass by without causing any harm. However, if the heart valves are damaged, or if a person has an artificial valve (see below), it's easier for bacteria to take root and bypass your normal immune response to infection.

Read more about the causes of endocarditis.

Symptoms of endocarditis

The initial symptoms of endocarditis are similar to the flu and include:

  • a high temperature (fever) of or above 38C (101.4F)
  • chills
  • headache
  • joint and muscle pain

Left untreated the infection will damage the valves of the heart, disrupting the normal flow of blood through the heart.

This triggers a range of life-threatening complications, such as:

  • heart failure – where the heart is unable to pump enough blood around the body to properly meet the body’s demands
  • stroke – where the supply of blood to the brain becomes disrupted

Read more about the symptoms of endocarditis.

Treating endocarditis

Endocarditis is treated with a course of antibiotics given via a drip. You will need to be admitted to hospital for this.

Around one in five people will also need surgery to repair or replace a damaged heart valve or drain away any abscesses that develop.

Endocarditis is a serious illness, especially if complications develop. Even with the highest standard of medical care the risk of dying is high – at around one in five. Early diagnosis and treatment is vital to improve the outlook for the condition.

Read more about the treatment of endocarditis.

Who is affected

You are more at risk of developing endocarditis if you:

  • have a prosthetic (artificial) heart valvevalve replacement surgery is increasingly being used when people experience narrowing of one of their heart valves
  • have congenital heart disease – congenital heart disease means a person is born with heart defects
  • have damaged heart valves because of infection or heart disease
  • inject drugs such as heroin – heroin users are three times more likely to develop endocarditis than the population at large

Even in these higher-risk groups, endocarditis remains a rare condition. In England, for example, endocarditis is estimated to affect around one in every 3,000 people in any given year.

Endocarditis is more common in older people, with half of all cases developing in people over 50. However, cases of endocarditis have been recorded in children, particularly those born with congenital heart disease. Twice as many men are affected as women.

Although it may sound strange, rates of endocarditis are increasing because of advancements in medical care. This is because an increasing number of people are now being treated with valve replacement surgery or surgery to repair congenital heart disease.

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Page last reviewed: 04/04/2014

Next review due: 04/04/2016