Bacterial Endocarditis Prophylaxis

Endocarditis is an infection of the inside lining of the heart (the endocardial lining). Endocarditis is usually caused by a bacterial infection and can involve the endocardial lining of the heart valves and of the heart muscle itself. Giving antibiotics to try to prevent endocarditis is referred to as "endocarditis prophylaxis."

Red and white capsule pushed through the foil back of a package of medicine

The Rationale Behind Endocarditis Prophylaxis

Because endocarditis can destroy the heart muscle and heart valves, it is always a serious problem and is often life-threatening. Furthermore, endocarditis can be quite difficult to treat, since treatment may require several weeks of intravenous antibiotics, and occasionally requires open heart surgery. Obviously, it is better to prevent endocarditis than to treat it.

While major clinical trials proving the effectiveness of endocarditis prophylaxis are lacking, there are strong theoretical grounds for its use.

The Theory of Endocarditis Prophylaxis

In most people, when a small number of bacteria enter the bloodstream, the body's defense mechanism can clear the bacteria from the blood quickly and efficiently.

However, in people who have certain kinds of heart problems, the bacteria can get trapped within turbulent blood flow inside the heart, and subsequently "stick" to the endocardial lining, where they can cause an infection.

The idea behind endocarditis prophylaxis is to use antibiotics to kill any bacteria that enter the bloodstream before they have a chance to set up an infection within the heart.

For this reason, experts recommend that people who have a high risk of developing endocarditis ought to receive prophylactic antibiotics before having medical procedures that are likely to introduce bacteria into the bloodstream.

When Should Prophylaxis Be Used?

Recent evidence suggests that most people with heart conditions are actually at substantially lower risk for endocarditis than previously believed, and therefore do not need endocarditis prophylaxis. The guidelines have been substantially updated by the American Heart Association and American College of Cardiology to reflect this new understanding.

Endocarditis prophylaxis is now recommended only for people who are at the highest risk for endocarditis.

These include:

  • patients with artificial heart valves
  • patients who have had heart repairs using prosthetic material (note: this does not include coronary artery stents)
  • patients with a prior history of endocarditis
  • patients with certain unrepaired or incompletely repaired congenital heart disease
  • patients who have transplanted hearts who subsequently develop heart valve problems

It is worth noting that the current guidelines do not recommend endocarditis prophylaxis for most patients with aortic stenosis, aortic regurgitation, or mitral valve disease (including those with mitral valve prolapse), or for patients with hypertrophic cardiomyopathy.

Which Procedures?​

The new guidelines recommend prophylaxis only for these medical procedures:

  • dental procedures involving manipulation of the gums or the roots of the teeth, including routine dental cleaning.
  • procedures requiring incisions or biopsies of the respiratory tract or mouth, such as tonsillectomy, or bronchoscopy with biopsy.
  • procedures involving incisions of infected tissues.

Notably, antibiotic prophylaxis is no longer recommended for procedures of the gastrointestinal or genitourinary systems.

Which Antibiotics?

In general, amoxicillin is recommended as the antibiotic of choice if prophylaxis is needed. The American Heart Association has a guide to endocarditis prophylaxis that lists alternate antibiotics in case amoxicillin cannot be used.

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