Send letter to journal:
Re: Antimicrobial prophylaxis for endocarditis: emotion or science?

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.

Send letter to journal:
Re: Antimicrobial prophylaxis for endocarditis: Emotion or science

Dear Editor,

As cardiac surgeons we read and reread the editorial by Ashrafian and Bogle initially with interest and subsequently bemusement looking for a definitive message. The title was clear enough; the editorial was not.

The conclusion that good practice will be served if “patients are adequately counselled on the benefits of good dental hygiene and a discussion is undertaken and documented on the risks/benefits of antibiotic prophylaxis” is superficially attractive if one ignores the practicalities of who is making the decision and on what basis. Is this the responsibility of cardiologist or dentist? Does this mean the patient agreeing to bad advice is acceptable? I agree that dental practitioners are independent practitioners and carry legal responsibility for their commission (antibiotic administration) – but omission is equally legally liable. Whose advice should they follow and on what basis?

The representative cardiological bodies in UK, USA and Europe have all published guidelines on the prevention of infective endocarditis. Their guidance is clear. The guidance from BSAC on the other hand carries with it a feeling of selfrighteousness but its position is not rational. Ideally the working party felt a prospective double blind trial should be carried out and that withholding antibiotic prophylaxis for dental procedures was radical but logical. That being the case why compromise? If there are 1.35 million dental procedures performed on “at risk” patients each year (and how reliable is that figure?) there is certainly a substantial pool available for randomisation – why not push hard for what is believed to be right?

The science of endocarditis is clear enough – valves become infected secondary to bacteraemia. The argument that rabbit models do not replicate strictly the pathogenesis of endocarditis in humans and as such the evidence is questionable confines much of 20th century progress to the intellectual dustbin. The incidence of endocarditis will depend on the organism type, the immune status of the patient and the bacteriological load. The argument that the patients with cardiac abnormalities are at risk all year round and therefore should not be covered at recognizable points when bacteraemia is predictable and can be adequately covered beggars belief. People die in cars despite or because of seatbelts – this does not render ‘belting up’ impractical or inappropriate nor reduce its effectiveness in saving lives. The risk of antibiotic related death from penicillin anaphylaxis (quoted in the editorial) as five times higher that the risk of IE is unreferenced (and in our experience unbelievable) and gives no indication of IE risk without antibiotics. Patients undergoing dental procedures develop bacteraemias with a higher bacteriological load than the background risk from chewing or brushing. Doctors and dentists cannot cover patient risk at all times. However they have a duty to reasonably cover risks that are recognizable and potentially treatable. No treatment is 100% effective: antibiotic prophylaxis should not be expected to be so. Failure to stop all events does not indicate ineffectiveness in the majority. If the philosophy followed is that the risk of dental treatment is tiny why cover any patients at all – the argument of covering patients at particularly high risk if they become infected applies to all patients not just those with prostheses or shunts. Endocarditis as a whole carries a mortality of at least 20% despite best available management. Likewise, if the background risk is so small, why should a patient who has suffered endocarditis represent a higher risk of infection than one, with equivalent pathology, who has not? This does not appear a rational stance (from a group who require hard evidence). Isn’t this emotion rather than science?

The BSAC guidelines go on to outline indications for non-dental procedures which by their own admission are “inferred by two equally unsatisfactory sources” – the chance of a procedure causing bacteraemia and whether such procedures have been anecdotally linked to endocarditis – exactly the evidence they find uncompelling in relation to dental prophylaxis. It does not appear reasonable to adopt two differing levels of proof for the same type of evidence.

Bacterial endocarditis is a severe life threatening infection with significant mortality and morbidity which despite best efforts and prophylactic therapy continues to present on a regular basis in a typical cardiological and cardiac surgical practice. Most clinicians can anecdotally confirm the association of infection following dental intervention. Appendix 1 in the BSAC guidelines states “patients should concentrate on achieving and keeping a high standard of oral and dental hygiene, as this does reduce the risk of endocarditis.” The presumption is minimisation of the level of bacteraemia associated with chewing and brushing will reduce the background risk of endocarditis. The same rational should therefore be applied to recognizable periods of increased bacteraemia.

The advice from BSAC has produced a situation where confusion reigns. Although dentists may not use the defence of the “the cardiologist made me do it” likewise “BSAC told me so” is unlikely to be more effective.

Recommendations of this nature adopted unilaterally against the best advice of representative cardiological bodies put dentists in an invidious position. They will be liable for omissions in cover and are unlikely to be supported if the treatment given runs contrary to the recommendations of the patient’s cardiologist. I would doubt clinicians outside the UK are likely to find the reasoning of BSAC compelling or defensible.

Patients deserve clear and consistent advice from their clinicians. Unfortunately the advice inherent in the guidelines and your editorial will not have helped to foster either.

Mr John AC Chalmers FRCS
Consultant Cardiac Surgeon
The Cardiothoracic Centre
Thomas Drive
Liverpool
L14 3PE

Mr D M Pullan FRCS
Consultant Cardiac Surgeon and Clinical Director
The Cardiothoracic Centre

References

1. Ashrafian H, Bogle R.
Antimicrobial prophylaxis for endocarditis: Emotion or science
Heart 2007; 93:5-6

Send letter to journal:
Re: Dentistry and endocarditis: beyond antibiotics

Dear Editor,

In the report by Ashrafian1 and Bogle, the authors highlight new recommendations by the British Society for Antimicrobial Chemotherapy to limit prophylaxis to high-risk patients with previously documented endocarditis or surgical shunt/valve procedures (1). Although dental prophylaxis have an impact on systemic disease, they do not eliminate bacteremia altogether. Thus, in addition to antibiotic therapy, education and additional treatment modalities should also be available to prevent systemic conditions following dental procedures (2-3).

Reports indicate that regular postgraduate courses may be an effective avenue to educate practioners on appropriate antibiotic usage in patients with endocarditis. (4). As well, treatment options like stannous fluoride (5) and preventative care (6) may provide additional systemic protection to patients. Finally, a review of individual dental practices may also curb inappropriate antibiotic usuage (7).

References

1. Ashrafian H, Bogle RG.
Antimicrobial prophylaxis for endocarditis: emotion or science?
Heart 2007; 93: 5-6.

2. Ito HO.
Infective endocarditis and dental procedures: evidence, pathogenesis, and prevention.
J Med Invest. 2006; 53(3-4):189-98

3. Brincat M, Savarrio L, Saunders W.
Endodontics and infective endocarditis--is antimicrobial chemoprophylaxis required?
Int Endod J. 2006; 39(9):671-82.

4. Demirbas F, Gjermo PE, Preus HR.
Antibiotic prescribing practices among Norwegian dentists.
Acta Odontol Scand. 2006; 64(6):355-9.

5. Ramji N, Baig A, He T, Lawless MA, Saletta L, Suszcynsky-Meister E, Coggan J.
Sustained antibacterial actions of a new stabilized stannous fluoride dentifrice containing sodium hexametaphosphate.
Compend Contin Educ Dent. 2005; 26(9 Suppl 1):19-28.

6. Gottehrer NR, Berglund SE.
Antimicrobial host response therapy in periodontics: a modern way to manage disease.
Dent Today. 2006 Sep;25(9):84-7.

Send letter to journal:
Re: Antimicobial Prophylaxis for Endocarditis: Emotion or Science?

Dear Editor,

The editorial by Ashrafian and Bogle[1] suggests that the authors have little clinical experience in the management of patients with infective endocarditis (IE). The body of cardiologists and cardiac surgeons in Europe, North America and the UK would disagree that the BSAC guidelines are important or “a step in the right direction” and almost certainly the guidelines will be disregarded by the rest of the world as an eccentricity not based on any evidence whatsoever. Without doubt, they are out of line with the views of physicians who have cared for patients with IE over the last 50 years and of those who continue to have this responsibility. The Joint Formulary Committee of the British National Formulary and our dental colleagues would do well to take note of the advice from specialist cardiologists from Europe and the USA regarding antibiotic prophylaxis (ABP) for those at risk of IE and remember the devastating consequences that often occur in those patients who are unfortunately affected. Sadly, within our own Centre we have recently seen two patients who developed IE after dental treatment who despite requesting ABP from their dentist, were told that based on the new BSAC guidelines ABP was not necessary and hence not administered.

Although a very large randomised controlled clinical trial of ABP prior to dental treatment in those patients considered to be at high/moderate risk of IE because of their cardiac structural abnormality might help quantify the benefit/risks of ABP, we think it would prove difficult to obtain ethical approval and even the patients’ consent for such a study. With regards to the cost-effectiveness and safety of oral amoxicillin, we believe it is very cost-effective at ₤1.50 per 3G sachet, set against the high cost of a prolonged in-patient stay for parenterally administered antibiotics, the high morbidity and mortality and the need for surgery in those individuals with the serious destructive cardiac and extracardiac complications of IE. Although anaphylaxis may occur as an allergic response to penicillin, this is extremely rare and not a reason for the omission of ABP.

Patients who place their trust in health professionals to do everything in their power to protect them deserve a sensible cautious approach from their physician to diminish the risk of developing a life- threatening illness with high morbidity and mortality. Dentists look to cardiologists and not microbiologists for advice about the need for ABP for patients with cardiac abnormalities that place them at increased risk of IE. Not to offer ABP to those patients who cardiologists consider to be at risk of IE is a disservice and in most countries in the Western World would be considered medico-legally negligent. Dentists will find it difficult to obtain the support of the patient’s cardiologist when disaster strikes their patient as a result of omitting ABP when this has been recommended.

Dr David R Ramsdale MD FRCP, Consultant Cardiologist and Dr Nick D Palmer MD MRCP, Consultant Cardiologist,
The Cardiothoracic Centre,
Thomas Drive,
Liverpool.

Reference