Sir, the comments of Longman et al1 were certainly of some concern to us and deserve a response.

As cardiologists and cardiac surgeons working in a large dedicated Cardiothoracic Centre, we are acutely aware of the devastating consequences of infective endocarditis (IE) that occur in patients with predisposing cardiac abnormalities who have undergone dental, interventional or surgical procedures known to cause bacteraemia.

Patients with previous IE, complex cyanotic congenital heart disease, prosthetic heart valves and patients with mitral valve prolapse with significant mitral regurgitation are at highest risk.

The morbidity and mortality in patients with IE remain high despite prolonged in-patient treatment with intravenous antibiotics and cardiac surgical intervention. The cardiac manifestations include heart failure from severe aortic and/or mitral valve regurgitation, fistulous communications and false aneurysm formation.

Cardiac and paravalvar abscesses may be so extensive as to cause heart block requiring pacemaker implantation and local tissue destruction may make surgery impossible.

They are often lethal complications. The extracardiac embolic and vasculitic complications may affect every organ system.

They include retinal and peripheral limb emboli but the cerebral, renal and gastrointestinal complications are most serious. Cerebral infarction, cerebritis, cerebral abscess and cerebral haemorrhage may occur causing stroke, seizures and death.

Ruptured mycotic aneurysms may result in intracerebral or subarachnoid haemorrhage. Renal infarction and glomerulonephritis cause renal failure.

Splenic infarction, abscess and rupture may be lethal and demand urgent abdominal surgery in an already compromised patient. Bowel infarction and peritonitis is frequently fatal. Prosthetic valve endocarditis is particularly serious and usually requires cardiac surgical intervention with high operative morbidity and mortality.

It is because of these life-threatening and severe disabling complications that every effort should be made to prevent IE. The Guidance on the Prophylaxis and Treatment of Infective Endocarditis in Adults from the Advisory Group of the British Cardiac Society Clinical Practice Committee and the Royal College of Physicians Clinical Effectiveness and Evaluation Unit will soon be published on the British Cardiac Society's website along with the levels of evidence and grades of recommendations.2

Not only will this include recommendations on diagnosis and investigation but advice on antibiotic prophylaxis, medical treatment, indications for surgery and other topics. Wherever possible (and the document has some 800+ references) the evidence linking procedures with IE is presented.

Although it is fair to say that the strength of evidence associating procedures and subsequent endocarditis is not high, it is based on evidence of associated bacteraemia, case reports, experimental, animal and case-controlled studies and the expertise of the Advisory Group as well as the opinions of expert committees that have reported in the literature rather than randomized controlled clinical trial data.

The Guidance document is consistent with that published recently by the European Society of Cardiology3 and previously by the American Heart Association/American College of Cardiology.4 We believe that the recommendations are based on the best evidence available, are clear and capable of realistic implementation.

It is untrue to say that the intravenous regimens are complicated. High-risk patients including those with prosthetic valves are recommended to receive oral amoxicillin and this will be updated soon on www.rcseng.ac.uk.

However, we feel that those patients with previous IE warrant special attention to prevent further episodes because the consequences are so serious.

This should include intravenous prophylaxis – if necessary as an in-patient. We disagree with the suggestion that this is a frequent occurrence that presents a barrier to patient care in dentistry.

The risks of intravenous antibiotic administration are small and the advantages outweigh by far the disadvantages of leaving such patients inadequately protected. It is certainly not mainstream opinion among cardiologists and cardiac surgeons (and hopefully dentists) that current regimens for antibiotic prophylaxis are unnecessarily stringent.

It would appear that it is not the view of Longman and colleagues either, since they advocate continuing to adhere to the BSAC recommendations issued in 1992/3!5,6 With regard to the type of dental procedures that warrant antibiotic prophylaxis, the recommendations are based on the association with significant bacteraemia and hence the risk of producing IE in patients deemed to be at increased risk.

The BCS document refers to the relevant papers. Since IE occurs when bacteria seed the endothelium damaged by high velocity jets (and this is supported by experimental and pathological observation), patients at risk of developing endocarditis should be offered protection by antibiotic prophylaxis when undergoing bacteraemia-inducing procedures, even though specific case reports linking the procedure to endocarditis do not exist.

We cannot support the view that antibiotic prophylaxis should be withheld from such patients until several supporting case reports appear in the literature or data from a randomized clinical trial is available. This we would consider to be suboptimal if not unethical treatment.