Confusing guidelines

Sir, we welcome the recent change to antibiotic prophylaxis,¹ as we are sure many others do, and have been keen to adopt the new practice. As a result it is now simpler to identify patients requiring cover, at least those in the first two groups (previous endocarditis or cardiac valve replacement), many of whom are already aware of their need to inform their dentist. However, regarding the third group in whom antibiotic prophylaxis is advised, we were unclear which surgical procedures are encompassed by the term 'surgically constructed systemic or pulmonary shunt or conduit'. To add to our confusion, in the recent BDJ editorial² the term 'surgically-constructed systemic pulmonary shunts or conduit' is used. One of the 'or's' has disappeared!

We informally approached a cardiologist and personal friend for further advice. In his opinion, the phrase 'surgically constructed systemic or pulmonary shunt or conduit' is too non-specific and, if taken literally, would encompass a number of procedures which do not require antibiotic prophylaxis, such as coronary artery or femoral artery bypass grafts. However, it is likely that the term is intended to describe only those procedures where a shunt or conduit is used to link systemic and pulmonary circulations, in which case the version in the BDJ may be more accurate and not simply a typographical error.

The vast majority of patients undergoing such procedures are children with congenital heart disease, including conditions such as Tetralogy of Fallot and pulmonary or tricuspid atresia. Although community or special needs dentists may be most likely to see these children, the development of such surgical techniques has led to the survival of many into young adulthood and some may lead relatively normal lives, quite possibly presenting to a general dental practitioner. While many of these patients' cardiologists may be able to advise on the nature of their previous surgery and the need for antibiotic prophylaxis, we feel that the new guidelines fail to clearly define the patient groups at high-risk of infective endocarditis and who still require antibiotic prophylaxis. New guidelines may be confusing if it is difficult to determine to which patient groups they are to be applied.

We wish to thank Dr Dwayne Conway MD MRCP for cardiological advice and help in preparing this letter.

Dr Michael Martin responds to the above letters: I would like to thank everyone who has contacted me by a letter to the BDJ and by other means following my editorial. ³ There is no doubt everyone agrees that infective endocarditis (IE) is a devastating disease with very serious potential sequelae. Anything that can be done to avoid this disease should be done. The essence of the differences between the working party of the British Society for Antimicrobial Chemotherapy (BSAC) on IE and the advice of the specialist societies such as the British Cardiac Society, is scientific evidence. The BSAC working party reviewed, I am sure as I have, all the available evidence linking IE and dentistry. Most of the evidence is at best anecdotal and very poorly documented. Some clinicians like Dr McKay have seen patients with IE associated with dentistry, but definitive literature written in peer-reviewed case reports is lacking. All the retrospective and other analyses do not support a strong link between dentistry and IE.

The concept of a 'significant bacteraemia' as described by the BCS report and relating it to risk as Dr Shanson suggests is an interesting concept. ⁴ Unfortunately this approach is fraught with inconsistencies, as toothbrushing would be considered a significant risk if this approach is adopted. The risk of infective endocarditis cannot be simply linked to numbers of bacteria recovered from the blood stream, but probably to a myriad of other factors such as surface adhesins, cryptotopic expression of oral streptococci and many other properties. Many of these factors need to be evaluated at a molecular level before risk can be properly estimated.

This debate about IE and dentistry will I am sure continue to run, but personally I am pleased that the BSAC working party have produced a report based on evidence. If there is a legal challenge after April 2006 linking dentistry and IE as Dr Zafarulla and Dr Fayle suggest, then I am sure that the BSAC working party will be regarded by courts as the sole competent authority; this has been the case in over 300 previous medico-legal disputes.⁵

I welcome the fact that that Dr Cockcroft, the Chief Dental Officer, has asked NICE to look again at this subject. I hope that NICE will consult widely and above all consider the available scientific and relevant documented clinical evidence. I will however be surprised if the conclusions of NICE do not reflect those of the BSAC working party on infective endocarditis.