Antimicrobial prophylaxis for endocarditis: emotion or science?

David H Roberts, Consultant Cardiologist,

Other Contributors:

February 19, 2007

Dear Editor,

The debate on the role of antimicrobial prophylaxis to prevent infective endocarditis (IE) has intensified as a consequence of the recently published guidelines from the Working Party of the British Society for Antimicrobial Chemotherapy (BSAC). In the review by Ashrafian and Bogle, reference is made to the dental community’s satisfaction with these new guidelines, highlighting a “victory for science and common sense”. Cardiologists are likely to question the validity of such a statement. The decision by BSAC to exclude patients deemed at “intermediate risk” of developing endocarditis from bacteraemia, induced by dental or surgical procedures is raising alarm bells in the cardiology community. Cardiologists are the people most able to risk stratify patients with acquired or congenital heart disease in relation to IE prophylaxis. For example, Ashrafian and Bogle quote mitral valve prolapse (MVP) in relation to the need for prophylaxis. MVP associated with a turbulent jet of mitral regurgitation is more likely to produce endocardial disruption than ‘slight prolapse of the posterior mitral leaflet’, yet both are regarded equal under the BSAC guidelines.

A change in clinical practice will occur with the BSAC guidelines which is certain to cause confusion both to the patient and the dentist (or any other surgical practitioner) involved in patient care. Over the years, patients, cardiologists and dental practitioners have communicated well. Dental practitioners will often write to cardiologists seeking advice on specific antibiotic dosage or timing etc. and this may have positively contributed to the present low annual case load of IE. No cardiologist would argue against the statement that many cases of IE are of non-dental origin but many are likely to question the decision to withhold prophylaxis for general surgical or genito-urinary procedures in patients with haemodynamically significant murmurs.

Ashrafian and Bogle highlight the risk of anaphylaxis associated with severe penicillin allergy. Most allergies to antibiotics are not life- threatening however and will often have declared themselves previously by taking a careful medical history. Several alternative antibiotics are also now available to substitute for a penicillin preparation when concerns over potential allergy are raised.

Cardiologists are at the ‘front line’ in the treatment of patients with IE and recognise the high morbidity and mortality associated with the condition. It is unlikely therefore that the British Cardiovascular Society will support the new guidelines. It is extremely unlikely organisations such as the American Heart Association will do so also for fear of litigation issues. The benefits of antibiotic prophylaxis for IE outweigh the risk for more patients than is presently recommended by the BSAC. The debate must continue.

Conflict of Interest

None declared