Infective Endocarditis

Infective endocarditis is a serious infection of the interior lining of the heart (the endocardium) or heart valves. Left untreated, endocarditis can cause heart valve damage or destruction, blood clots, arrhythmias, and congestive heart failure. Although many heart patients are at an increased risk for developing infective endocarditis, most do not. Approximately 29,000 cases are diagnosed each year.

What Causes Infective Endocarditis?

The infection that leads to endocarditis can be caused by bacteria, fungi, or other microorganisms that enter the bloodstream. If normal microorganisms that live on skin, in the mouth, in the intestines, and in the urinary tract gain access to the bloodstream of certain heart patients, a serious infection can result.

For most people, the entry of these types of microorganisms into the bloodstream does not pose a problem. However, a patient with an abnormal heart valve or damaged endocardium can develop endocarditis when these microorganisms gain access to the bloodstream and become trapped within the layers of cells that are in the process of healing the damage. “Clumps” called vegetations develop at the healing sites within the heart and on the heart valves. Vegetations are dangerous because they can break off, enter the bloodstream, and block a blood vessel.

Who is at Risk for Developing Infective Endocarditis?

Infective endocarditis rarely occurs in people with normal hearts; the risk is in patients with existing heart problems. It is more common in individuals who are older than 50, and men are affected more often than women. The patients who are most commonly affected by infective endocarditis have also had:

Heart valve disease
• Heart valve replacement
• An artificial (prosthetic) heart valve
• A heart transplant
• A non-repaired congenital heart defect
• A prior history of infective endocarditis
• A history of rheumatic fever that scarred the heart valves
• A history of intravenous drug use
• Hypertrophic cardiomyopathy

Patients who have had successful repair of a congenital heart defect (including a ventricular septal defect, an atrial septal defect, or a patent ductus arteriosus) are usually no longer at increased risk for infective endocarditis.


Patients with acute (recent onset) endocarditis experience the flu-like symptoms of fever, night sweats, muscle ache, muscle pain, and decreased energy. Patients with long-term (chronic) endocarditis suffer from fever, chills, tiredness, weight loss, joint pain, night sweats, and the symptoms of heart failure. Chronic endocarditis and its symptoms may last for months.

Other notable symptoms often found include red spots on the palms of the hands and soles of the feet (Janeway lesions); red, painful sores on the tips of the fingers and toes (Osler’s nodes); small, dark lines under the fingernails that look like wood splinters (splinter hemorrhages); and retinal blood vessels that have burst (Roth’s spots).


Infective endocarditis is diagnosed by its symptoms and the patient’s heart-related medical history. A new heart murmur or a change in the sound of an old heart murmur might be heard. Blood samples are collected from different areas of the body and cultured for the offending microorganisms.

Echocardiography, the most reliable tool for diagnosing infective endocarditis, is used to visualize heart valve structure and function, heart wall motion, and overall heart size. Other imaging techniques, such as transesophageal echocardiography (TEE), computed tomography (CT) scanning, and magnetic resonance imaging (MRI), may also be used when necessary.


In past years, the American Heart Association (AHA) recommended that patients at increased risk for endocarditis take prophylactic (preventative) antibiotic medication before certain dental and surgical procedures. However, in 2008, the AHA Endocarditis Committee, along with national and international experts, extensively reviewed published studies and found no conclusive evidence linking these procedures with the development of endocarditis. They also concluded that endocarditis is much more likely to be caused by frequent exposure to the random microorganisms associated with daily activities.

Therefore, the past practice of prescribing antibiotics prior to a dental procedure is no longer recommended EXCEPT for patients with the highest risk of adverse outcome. The AHA further recognizes and emphasizes the importance of good oral and dental health, including regular brushing and flossing and regular visits to the dentist for patients at risk for endocarditis.


Antibiotics with proven results against the particular microorganism found in the patient’s blood cultures are considered the first line of treatment for infective endocarditis. Most of these powerful antibiotics are administered intravenously in the hospital. Subsequent blood tests are performed to determine if the treatment is working. If the vegetations progress to the point that the heart valves are damaged or destroyed, surgery may be necessary.

American Heart Association
Texas Heart Institute