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 almost always requires several weeks of intravenous antibiotics, and occasionally requires open heart surgery.
Obviously, it is better to prevent endocarditis than to treat it.
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 attempt 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, 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. Accordingly, the American Heart Association made a major revision in their guidelines on endocarditis prophylaxis in 2007, so that prophylaxis is now recommended for many fewer patients, and for fewer procedures, than previously.
Which Patients Need Endocarditis Prophylaxis?
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 now have developed heart valve problems
It is worth noting that the current guidelines do not recommend endocarditis prophylaxis for most patients with aortic 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:
- dental procedures involving manipulation of the gums or the roots of the teeth
- procedures of the respiratory tract
- procedures involving infected tissues
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.
Wilson W, Taubert KA, Gewitz M, et al. "Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group." Circulation. 2007 Oct 9;116(15):1736-54. http://www.americanheart.org/presenter.jhtml?identifier=11086 (accessed January 13, 2010).