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Infective Endocarditis Prophylaxis

The following information is taken from the National Heart Foundation "Guideline for the Prevention of Infective Endocarditis associated with Dental and other Medical Interventions” (December 2008). The Heart Foundation has given permission for sections of these guidelines to be reproduced here. The full guidelines, including references, are available from the National Heart Foundation website (www.heartfoundation.org.nz) under Programmes and Resources > Health Professionals > Guidelines and position statements > Infective Endocarditis, or The National Heart Foundation of New Zealand, PO Box 17160, Greenlane, Auckland 1130.

Cardiac Conditions

The number of cardiac conditions for which prophylaxis is recommended has been reduced significantly (see below). These conditions have been selected because of a high lifetime risk of endocarditis and a high risk of mortality or major morbidity resulting from bacterial endocarditis, should it occur. In line with other recent recommendations we no longer recommend differentiation into high and moderate-risk groups.

The main difference from other recent national recommendations is the retention of rheumatic heart disease in the list of conditions requiring prophylaxis. This reflects the known high lifetime risk of endocarditis in this population and the potential for significant adverse outcomes after endocarditis. Rheumatic heart disease remains a major cause of morbidity and mortality in New Zealand and our recommendations take into account this difference from other developed countries. Although it is possible that the risk of endocarditis may differ with the severity of rheumatic valvular involvement, there is no clear evidence to this effect and prophylaxis is therefore recommended regardless of severity. Prophylaxis is not recommended for those who have had previous rheumatic fever without cardiac involvement. We hope that this pragmatic approach will allow for straightforward interpretation.

Cardiac conditions for which endocarditis prophylaxis is recommended

Dental Care

This new NHF guideline highlights the imperative that at-risk patients should remain free of dental disease. This requires emphasis on improved access to dental care and improved oral health in patients with underlying cardiac risk factors for infective endocarditis, rather than a sole focus on dental procedures and antibacterial prophylaxis.

Optimal oral health is maintained through regular professional care and the use of appropriate products such as manual and powered toothbrushes, floss and other plaque-control devices such as antibacterial mouthwashes. Patients need to be strongly advised to comply with a continuing oral and dental care regimen.

Treatments to achieve this goal include:

• Removal of impacted teeth and unerupted teeth.
• Treatment of all teeth with periapical disease by endodontic debridement and root filling or apical surgery or extraction.
• Removal of all carious teeth that cannot be restored.
• Treatment of other abnormalities such as cysts or intra-bony lesions associated with the dentition and related structures.
• Treatment of oral ulcers including those caused by ill-fitting or irritating dental appliances.
• Treatment of inflammatory periodontal disease.
• Oral hygiene instructions for the patient to ensure maintenance of ideal oral health.

Dental procedures (plus tonsillectomy/adenoidectomy) for which endocarditis prophylaxis is recommended

Non-Dental Procedures

Endocarditis prophylaxis is no longer recommended for non-dental procedures (including respiratory, gastrointestinal and genitourinary procedures), unless the procedure is at a site of established infection (see Antibacterial regimen for surgery/procedures at sites of established infection). Antibacterial prophylaxis to prevent non-endocarditis infections after these procedures may be indicated but recommendations for this are not within the scope of this guideline.

Education and Identification of At-Risk Patients

District Health Boards and other organizations where at-risk patients may be identified are responsible for educating patients and staff about the need for good dental care and appropriate antibacterial prophylaxis. Patient education cards and resources for dentists and healthcare professionals are available from the Heart Foundation.

Electronic alerts should be placed for these patients in appropriate public and private medical information systems. From a dental practitioner's perspective, the Heart Foundation wishes to re-emphasize the need for improved access to dental care and improved oral health in patients with underlying cardiac risk factors for infective endocarditis, rather than a sole focus on dental procedures and antibacterial prophylaxis.

Antibacterial Prophylaxis

Prophylaxis for dental procedures and tonsillectomy is directed against viridans streptococci. While they are not the only organisms that cause bacteraemia following these procedures, they are the organisms most likely to cause endocarditis.

There have been many reports of viridans streptococci with reduced susceptibility to penicillins, both in New Zealand and internationally. These strains are typically also less susceptible to cephalosporins, especially the oral first-generation cephalosporins. This has contributed to our decision to no longer recommend cephalosporins as oral alternatives. Viridans streptococci have shown a similar increase in resistance to macrolides while their resistance to clindamycin has also increased, but to a lesser extent.

The principles of prophylaxis for prevention of endocarditis from viridans streptococci have been well established in animal models. Successful prophylaxis depends more on prolonged antibacterial activity than prevention of bacteraemia. Indeed, failure of a regimen to suppress post-procedure bacteraemia is not a surrogate marker for failure of prophylaxis. Because of this, both bactericidal (e.g., amoxicillin) and bacteriostatic or non-killing regimens (e.g., clindamycin or clarithromycin) are very effective so long as the antibacterial agent is present in the blood stream for long enough. This can be achieved with a single dose of these agents, provided the correct dosage is given.

Antibacterial regimen for dental procedures (plus tonsillectomy/adenoidectomy)

Prophylaxis is optimal when antibacterial treatment is begun just before the procedure, to ensure adequate levels are present in the blood stream at the time of the procedure. If it is begun hours or days beforehand, it may select strains with decreased susceptibility so that if endocarditis occurs it is more difficult to treat.

Bacteraemia may complicate established focal infection and its surgical management at any site, such as drainage of an abscess (dental, skin and soft tissues, lung etc) or of peritonitis. It may also complicate procedures (including urinary catheterization) through infected fluids, such as urine, bile or peritoneal fluid. At all of these sites bacteria commonly associated with infective endocarditis may be present. Patients with established infections at these sites will necessarily receive antibacterial treatment and those at cardiac risk are advised to have appropriate antibacterial agents included (see below) in their overall antibacterial regimen before their procedure.

Antibacterial regimen for surgery/procedures at sites of established infection

Topic Code: 1352