Endocarditis is the growth of blood clots on the valves and inner walls of the heart. They can cause damage to the heart. The growths can also break off and block blood flow in other areas of the body such as the brain or lungs.


Certain health problems let the blood to clot too easily. The clots can form and stick in any blood vessel or in the heart. Areas of damage, like a defective heart valve, are ideal places for clots to stick and grow. The heart valve may be scarred from an illness or a birth defect.

Blood Flow through the Heart
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Risk Factors

Your chances of endocarditis are higher if you have:

  • Cancer
  • Blood clotting disorders such as disseminated intravascular coagulation
  • A bloodstream infection
  • HIV infection
  • Immune system disorders such as systemic lupus erythematosus



Endocarditis itself doesn't cause symptoms. Growths that have broken off can block the flow of blood. This can cause symptoms. Examples are symptoms of a heart attack or stroke.


You will be asked about your symptoms and health history. A physical exam will be done. The doctor may test for endocarditis if there have been problems with blood clots.

You may have:

  • Blood tests—to check for infection or clot issues
  • Echocardiogram—to view heart and heart valves



The goal is to stop the growth of more clots. This will help to prevent complications like a stroke. Medicine can make it harder for blood to clot. This can stop clots, but also increase the risk of bleeding.

Related conditions that increase the risk of blood clots will also need to be treated.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.


American Heart Association https://www.heart.org 

National Heart, Lung, and Blood Institute https://www.nhlbi.nih.gov 


Heart and Stroke Foundation of Canada https://www.heartandstroke.ca 

Public Health Agency of Canada https://www.canada.ca 


Nonbacterial thrombotic endocarditis (NBTE). EBSCO DynaMed Plus website. Available at:  http://www.dynamed.com/topics/dmp~AN~T115203/Nonbacterial-thrombotic-endocarditis-NBTE . Updated June 7, 2017. Accessed January 7, 2019.

Noninfective endocarditis. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/cardiovascular-disorders/endocarditis/noninfective-endocarditis. Updated September 2017. Accessed January 7, 2019.