Introduction

Introduction

Infective endocarditis (IE) is a rare (13.8 cases per 100,000 individuals per year in the general population)¹ but life-threatening infection of the endocardium, particularly affecting the heart valves. It can be difficult to diagnose, case fatality rates are approximately 30%^2,3 and there is significant morbidity, with 20-50% of patients undergoing corrective cardiac surgery.^4-11 The incidence of IE is increased in individuals with predisposing cardiac conditions (see Patients at risk of infective endocarditis). IE incidence is approximately twenty times higher in those with moderate risk cardiac conditions (280 cases per 100,000 individuals per year) and approximately 36 times higher in those with high risk cardiac conditions (497 cases per 100,000 individuals per year).¹² These individuals are also at increased risk of the complications of IE. However, around 30-40% of new IE cases have no known predisposing cardiac disease.^12-14

Most cases in patients with a predisposing cardiac condition are caused by a bacterial infection originating from a transient bacteraemia.^5,6,15 Although streptococci of oral origin have been implicated in up to 45% of IE cases, recent reports suggest that the proportion of IE cases involving streptococci from a presumed oral source has fallen.^4-6,15-18 Studies suggest that less than 10% of patients diagnosed with IE underwent an invasive dental procedure in the 30 days prior to their IE diagnosis.^13,14 However, it should be noted that a lack of robust microbiological data continues to be a particular weakness of the supporting literature and advances in disease diagnosis, cardiac surgical techniques and biomaterials, as well as changes to patient risk factors and the re-classification of streptococcal species makes comparison of historical data challenging.

Previously, sporadic high-grade bacteraemias caused by dental procedures were thought to be the main risk factor for IE of oral origin, with consequent widespread use of antibiotic prophylaxis. However, there is reasonable consensus that cumulative, low grade bacteraemias, triggered by normal daily activities such as tooth brushing, flossing and chewing, may be of greater significance, emphasising the importance of maintaining good oral hygiene.^19,20 Additionally, the evidence-base for the efficacy of antibiotic prophylaxis in preventing IE is weak and views on the balance of benefits and harms have shifted in recent years, with moves to reduce the utilisation of antibiotic prophylaxis. Consequently, antibiotic prophylaxis is not the default option for most patients at risk of IE. 

The National Institute for Health and Care Excellence (NICE) Clinical Guideline 64 Prophylaxis Against Infective Endocarditis (CG64)²¹ states:

‘Antibiotic prophylaxis against infective endocarditis is not recommended routinely for people undergoing dental procedures.’

This recommendation reflects the lack of high certainty evidence to support the association between dental procedures and the development of IE and the use of antibiotic prophylaxis before dental procedures in patients at risk of infective endocarditis.^21,22 It also reflects concerns about the risk of adverse reactions to antibiotic prophylaxis and antibiotic stewardship considerations.

However, NICE acknowledges that there is a sub-group of individuals at high risk of IE who may benefit from antibiotic prophylaxis.^21,22 Identification of these individuals may require liaison with the patient’s cardiac team(s) and decisions about the appropriateness of antibiotic prophylaxis for different dental procedures will require discussion and shared decision-making with the patient.