The Facts

Endocarditis is an inflammation of the lining of the heart valves that is most often caused by infection. Most people who develop this condition already have heart problems and are over 60 years old, but it can occur at any age, including in children. While not very common, this can be a very serious disease. Men are more likely to be affected than women.

There are two types of endocarditis: infective and non-infective. With prompt treatment, the majority of people with infective endocarditis will survive. Non-infective endocarditis is more difficult to treat.


Some people are more likely than others to develop endocarditis. The following conditions increase the risk:

  • a history of rheumatic fever or rheumatic heart disease
  • a history of endocarditis
  • a congenital (present at birth) heart defect
  • prosthetic (artificial) heart valves
  • a history of intravenous drug use
  • mitral valve prolapse (MVP)
  • diabetes
  • poor dental hygiene or dental infection
  • chronic hemodialysis
  • coagulation disorders (e.g., antiphospholipid antibody syndrome)

Endocarditis develops in the endocardium, the inner tissue of the heart. It starts if this tissue has been damaged, injured, or infected. Much as a cut on the skin causes a scab to form, damage to the endocardium can lead to the formation of a blood and tissue clot (thrombus).

In acute infective endocarditis, the clots are caused by bacterial or fungal infection, inflaming and damaging the heart cells. The infection reaches the heart through blood that's carrying a concentration of bacteria, a condition called bacteremia. Once the infectious agent reaches the heart via the blood, it tends to concentrate around the valves – the blood’s point of entry and exit.  Despite the name, infective endocarditis isn't contagious.

The infecting agent can get into the blood through:

  • dental work and surgery
  • an infected cut on the skin
  • injecting drugs into veins
  • being fitted with artificial heart valves
  • a surgically implanted vascular access device (e.g., a PICC line, Hickman line, or Port-a-Cath)

In non-infective endocarditis, the clot may not be infected but interferes with heart valve function anyway. Some conditions make the formation of scar tissue on the heart valves more likely: