What is infective endocarditis?

Infective endocarditis (IE) is an infection of the heart’s inner surface which includes heart valves and the wall separating the chambers of the heart.  This condition results in valvular insufficiency leading to congestive heart failure and abscesses within the heart muscles.  Valvular insufficiency is when the heart valves cannot close perfectly leading to leakage of blood which causes your heart to work harder to pump blood.

In the United States, the 2009 incidence of IE was around 13 cases per 100,000 people and it is increasing annually at a rate of 2.4%.  In addition, more than 50% of people affected by IE is aged above 50 years.  Furthermore, it is 3 times more common in males than in females.

Seeking medical advice the earlier possible, decreases the risk of complications.  This condition may be fatal if left untreated.

What causes infective endocarditis?

Infective endocarditis is mainly caused by bacteria (Staphylococcus aureus), travelling through your bloodstream, that attach to your heart valves.  However, it can also be caused by fungi and other organisms.

Having a poor dental hygiene increases your risk of developing IE.  This is because the bacteria found in your mouth can reach your bloodstream to affect your heart, leading to IE.  In addition, having intravenous catheters for long periods of time can facilitate the entry of bacteria in your bloodstream.  Furthermore, intravenous drug abuse also facilitates the entry of bacteria in your bloodstream as usually these people do not use sterile syringes.

What are the risk factors for infective endocarditis?

Several factors may increase your risk of developing infective endocarditis and these include:

• Age: Being above the age of 50 years increases your risk of developing IE.
• Sex: Males are 3 times more at risk of developing IE than females.
• Prosthetic heart valves: These are also known as artificial heart valves.  Bacteria or other germs are more likely to attach to artificial valves than normal heart valves.
• Congenital heart defects: Having a heart defect such as abnormal heart valves or heart conditions since birth, increases your risk of developing IE.
• Damaged heart valves: Rheumatic fever or infection can damage your heart valves which increases your risk of developing IE.
• History of endocarditis: Having been affected by endocarditis in the past increases your risk of developing IE again as the latter may have already damaged your heart valves.
• Implanted heart devices: Bacteria can stick on implantable devices such as pacemakers, which may increase your risk of developing IE.

What are the signs and symptoms of infective endocarditis?

The signs and symptoms of infective endocarditis include:

• Fever
• Chills
• Loss of appetite
• Weight loss
• Malaise

• Headache
• Night sweats
• Muscle pain
• Shortness of breath
• Cough
• Joint pains
• Swelling of the abdomen, legs or feet
• Janeway lesions: red spots on the palms of your and soles of your feet
• Osler nodes: red painful spots on your toes or fingers

Making a diagnosis

To make a diagnosis, your doctor will first take a detailed history from you to know more about your symptoms.  After the history taking, your doctor will perform a thorough physical examination to look for signs of infective endocarditis.to confirm the diagnosis, your doctor may order some tests and these include:

• Blood and urine studies: These tests include complete blood count (CBC), electrolytes, blood urea nitrogen (BUN), creatinine, glucose, coagulation profile and urine microscopy.  Anaemia and presence of blood and protein in urine is common in people with infective endocarditis.
• Blood culture: This is one of the most important tests to be done as it determines the type of organism and degree of severity of the disease.  Usually, 2 sets of blood sample are taken initially before any antimicrobial therapy is started.  Furthermore, determining which organism is causing the disease will help to use the most appropriate antimicrobial therapy.
• Echocardiogram: This test uses sound waves to produce images about your heart.  It may even show a mass within the heart composed of an aggregation of microorganisms, platelets and inflammatory cells which is known as vegetation.  Vegetation is characteristic of infective endocarditis.

• Chest x-ray: Chest x-ray is done to assess whether there is any abnormality within your lungs.
• Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scan: These scans are useful to assess whether the infection has spread to the brain or other parts of the body. 

What are the treatments of infective endocarditis?

The management of infective endocarditis involves mainly medications and surgery.

Intravenous (IV) antibiotics are used for the treatment of bacterial infective endocarditis and are used for at least 4 weeks.  Antifungal pills are used to treat infective endocarditis caused by fungi.  Unfortunately, these pills need to be taken lifelong to prevent recurrence of the disease.

Persistent infective endocarditis or severely damaged heart valves are treated by heart valve surgery.  The valve may be repaired or replaced by an artificial valve.  Eventually, 15-25% of people with IE will require surgery.  In addition, people with IE along with congestive heart disease will require replacement of the heart valve.  Surgery may also be required if the infection has spread to the brain or other parts of the body.

What are the complications of infective endocarditis?

If infective endocarditis is left untreated, the following complications may ensue:

• Heart valve damage
• Heart failure
• Stroke
• Abscesses developing in the heart, lungs, brain and other parts of the body

• Pulmonary embolism (PE) due to blood clots or vegetations.  Pulmonary embolism occurs when a blood clot developed from elsewhere, gets lodged in one of the main arteries of the lungs, resulting in diminished or absence of blood supply which may even lead to death.  In people with IE, vegetations located on the heart valves may get dislodged to reach the lungs, causing PE.
• Kidney damage

Prognosis

The prognosis depends on whether complications develop or not.  Untreated IE, generally results in death.  However, seeking medical advice early can be lifesaving.  The mortality rate of IE is 14.5%.

J. Alastair, I. and Simon, M., 2016. Davidson's Essentials of Medicine. 2nd ed. London: ELSEVIER.

Parveen, K. and Michael, C., 2017. Kumar & Clarks Clinical Medicine. 9th ed. The Netherlands: ELSEVIER.

Brusch, J., 2020. Infective Endocarditis: Practice Essentials, Background, Pathophysiology. 

Brusch, J., 2020. Infective Endocarditis Treatment & Management: Approach Considerations, Antibiotic Therapy, Management Of S Aureus Bacteremia.