Endocarditis (inflammation of the lining of the heart)

If the lining of the heart becomes inflamed, this is known as endocarditis. It can be caused by pathogens or occur as the result of a pre-existing condition. Severe progression of the condition and complications can be avoided with early treatment of the inflammation. 

At a glance

  • Endocarditis is an inflammation of the inner lining of the heart (the endocardium).
  • Pathogens – disease-causing germs – are responsible for infective endocarditis.
  • With non-infective endocarditis, blood clots occur at a previously damaged heart valve and on the lining of the heart.
  • Most of the symptoms are not specific to this condition. However, the infective form almost always causes a high temperature.
  • Early treatment is important to avoid life-threatening complications.
  • Depending on the cause of the inflammation, antibiotics or anticoagulants (anti-clotting medication) are usually used to treat it.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

An older man clutches his chest

What is endocarditis?

Endocarditis is an inflammation of the inner lining of the heart. This lining is known as the endocardium. In most cases, the heart valves are also inflamed, as these are covered by the endocardium.

Endocarditis can be infective, i.e., caused by bacteria or other germs, or non-infective, i.e., caused by other factors. Non-infective endocarditis is also known as non-bacterial thrombotic endocarditis (NBTE). It can occur as a result of other serious conditions, such as cancer.

Severe progression and complications can be avoided with early diagnosis and treatment. 

What are the symptoms of endocarditis?

With acute infective endocarditis, there is almost always a sudden, very high temperature, often accompanied by chills. However, the inflammation can also evolve gradually, causing a slight fever over an extended period.

Other possible symptoms include:

  • weakness
  • headache
  • joint and muscle pain
  • loss of appetite, nausea and vomiting

The person may also experience symptoms that indicate a problem with the heart. These include:

  • chest pain
  • shortness of breath
  • heart sounds
  • an accelerated heartbeat

There may also be neurological symptoms, such as:

  • neck stiffness
  • impaired sensitivity
  • visual impairments

If the inflammation progresses, the following signs may be visible on the skin:

  • Osler nodes: painful, bluish-red nodules about the size of a lentil, which occur on the fingers and/or toes
  • Janeway lesions: painless, very small red lesions on the hands and feet
  • Petechiae (blood spots): red dots the size of a pinhead, which usually occur in one part of the body

Important: Unlike the infective form of endocarditis, non-bacterial thrombotic endocarditis (NBTE) normally produces no symptoms and, as a result, often goes unnoticed for a long time. If blood vessels frequently become blocked with blood clots, this can be an indicator of NBTE. 

What causes endocarditis?

Infective endocarditis is almost always caused by bacteria – usually streptococcal and staphylococcal bacteria. The most common type of bacteria to cause endocarditis is Staphylococcus aureus.

Infective endocarditis is almost always caused by bacteria.

Interesting fact: Almost half of the population carry Staphylococcus aureus without becoming ill. Under certain circumstances, for example, if the immune system is weakened, these bacteria can, however, trigger a wide range of illnesses. As well as endocarditis, they can, for example, cause sepsis (blood poisoning), pneumonia and erysipelas (an infection of the upper layers of the skin).

Non-bacterial thrombotic endocarditis occurs when blood platelets (thrombocytes) and blood proteins become deposited on previously damaged heart valves. This can occur as a result of other serious illnesses, such as cancer, tuberculosis or autoimmune diseases. 

What factors increase the risk of developing endocarditis?

Several factors and pre-existing conditions can increase the risk of developing endocarditis. 

Risk factors for infective endocarditis include:

People with the following conditions are at an elevated risk of developing non-bacterial thrombotic endocarditis:

  • cancer and autoimmune disorders
  • increased blood clotting
  • advanced renal insufficiency (poor kidney function)
  • severe burns

How common is endocarditis?

In developed countries, it is estimated that between 3 and 10 people in every 100,000 develop the infective form of endocarditis each year. Men are twice as likely as women to be affected. 

Infective endocarditis is rare, affecting about 3 to 10 people in every 100,000 each year in developed countries.

What is the outlook for someone with endocarditis?

With acute endocarditis, the patient’s condition deteriorates rapidly. The milder form that begins more gradually (subacute endocarditis) often goes unnoticed for a long time. 

If endocarditis is not detected and treated in good time, serious complications and long-term effects can occur – including death of the patient. Almost 25% of people who are treated in hospital for infective endocarditis will die either during treatment or later due to long-term effects.

Possible complications and long-term effects include:

How is endocarditis diagnosed?

It isn’t always easy to diagnose endocarditis due to the lack of specific symptoms.

During a consultation, a doctor will determine potential risk factors for endocarditis when taking a detailed medical history. These include, for example, an artificial heart valve or a congenital heart disease.

Other possible indicators are recent surgeries or dental treatments, during which pathogens may have entered the body.

If endocarditis is suspected, an echocardiogram and blood tests will usually be performed.

An echocardiogram or “echo” is an ultrasound scan of the heart. It allows doctors to check the structure and movement of the organ. 

Blood tests are performed to check for the presence of pathogens. Blood cultures are created in a lab, in which bacteria and fungi in the blood can grow. 

Further indications of an inflammation can also be found by measuring inflammatory markers and the level of white corpuscles (also known as white blood cells or leukocytes) in the blood.

Certain clotting factors in the blood may also point towards non-bacterial thrombotic endocarditis.

If doctors are still unable to make a definitive diagnosis following these tests, additional imaging techniques may be used, such as X-ray, computed tomography (CT), or magnetic resonance imaging (MRI).

How is endocarditis treated?

Antibiotics are used to treat endocarditis caused by bacteria. 

Antimycotics (anti-fungals) are used if the cause is a fungal infection. These drugs are usually administered over several weeks via an infusion into the bloodstream.

Treatment with medication is sometimes not sufficient to treat endocarditis – for example, if the heart valves are already seriously damaged by the inflammation and are no longer fully functional.

Surgery may be required in this case to prevent heart failure and other complications. The operation involves the surgeon removing the inflamed tissue and replacing the damaged heart valves with artificial valves. 

If the patient has non-bacterial thrombotic endocarditis (NBTE), treatment aims to prevent blood clots from forming. In most cases, the patient will need to take anticoagulants (anti-clotting medication) such as heparin on a long-term basis. Under certain circumstances, such as acute heart failure, surgery may also be required to treat NBTE. 

What aftercare is required for endocarditis?

Following treatment, doctors will check the patient’s heart using an ultrasound scan (echocardiogram). This scan determines the condition and functioning of the heart.

Blood tests are performed again to check certain blood values and levels of white corpuscles in the blood. This indicates whether the inflammation is reducing. Regular check-ups are an important element of aftercare for endocarditis. 

People who have recovered from endocarditis are advised to ensure good dental hygiene and to have regular preventive check-ups with a dentist. In advance of certain surgical procedures and dental treatments, it may be possible – in consultation with a doctor – to take antibiotics on a preventive basis to avoid developing endocarditis again. 

Important: As a general rule, antibiotics should not be taken on a preventive basis, as taking these drugs without good reason can promote the development of antibiotic resistance

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DynaMed (Internet), Ipswich (MA). Nonbacterial Thrombotic Endocarditis (NBTE). EBSCO Information Services. Record No. T115203. 2018 (1995). Aufgerufen am 14.03.2022.

Gupta A, Mendez MD. Endocarditis. [Updated 2021 July 22]. In: StatPearls (Internet). Treasure Island (FL): Statpearls Publishing. 2022 Jan-. Aufgerufen am 14.03.2022.

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In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen – IQWiG).

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