Who Needs Antibiotics Before Dental Work?
New Guidelines Limit Endocarditis Prophylaxis to High Risk Patients
Nov 9, 2009
Transient bacteremia after dental procedures – that is, the seeding of bacteria from the oral cavity into the bloodstream – is well documented. (Roberts GJ, et al. Duration, prevalence and intensity of bacteraemia after dental extractions in children. Heart. 2006;92[9]:1274-77)
It has long been assumed that the presence of bacteria in the bloodstream potentially leads to infection of damaged or otherwise abnormal heart valves, a condition known as bacterial endocarditis. Prevention of endocarditis with prophylactic antibiotics has been demonstrated in animal studies, but consensus on guidelines for human prophylaxis has been lacking. (Durack DT. Prevention of infective endocarditis. N Engl J Med. 1995;332[1]:38-44; and Wilson W, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation. 2007;116[15]:1736-54)
How Do Bacteria in the Bloodstream Infect Heart Valves?
Heart valves that are abnormal as the result of rheumatic heart disease, surgery, autoimmune illness, congenital defects, or prolapse can create turbulence in the usually smooth, laminar flow of blood through the heart. For years, physicians and dentists have believed that transient spikes in bloodborne bacteria after dental procedures allow the microorganisms to settle in quiescent areas -- "eddies" created near the damaged valves -- where they are relatively protected from the immune system.
Eventually, the bacteria multiply and colonize adjacent heart tissue, forming "vegetations" that serve as sources for widespread dissemination of bacteria to other organ systems. Endocarditis is thus a serious condition with a high mortality rate.
It is quite clear that the organisms responsible for many cases of endocarditis are bacteria that usually reside in the human oral cavity; further, many cases of bacterial endocarditis are discovered within a few months of patients having undergone invasive dental procedures (extraction, cleaning, periodontal elevation, etc.).
Therefore, dentists have been hesitant to perform any procedures on patients who have a history of heart disease, including those with audible murmurs (murmurs are the hallmark of turbulent blood flow around a heart valve).
Evidence Supports Antibiotic Prophylaxis Only for High Risk Patients
A recent Cochrane review of the scientific literature demonstrated that the practice of prescribing antibiotics to individuals with moderate risk for endocarditis – say, those with mitral valve prolapse – is not supported by current data. (Oliver R, et al. Antibiotics for the prophylaxis of bacterial endocarditis in dentistry. Cochrane Database Syst Rev. 2008;[4]:CD003813)
Specifically, the review found no difference in the risk for bacterial endocarditis between moderate-risk people who received prophylactic antibiotics and those who didn’t. Therefore, for individuals who are at moderate risk for endocarditis, the risks of prophylactic antibiotic use – anaphylaxis, diarrhea (including life-threatening C. difficile overgrowth), interstitial nephritis, etc. – may outweigh any potential benefit.
Given the weight of available data – and in the face of escalating problems with antibiotic resistance among bacterial pathogens – in 2007, the American Heart Association revised its guidelines for antibiotic prophylaxis for preventing bacterial endocarditis.
Individuals who should be considered for antibiotic prophylaxis prior to undergoing dental procedures include:
- heart transplant patients who develop cardiac valvulopathy (valvular damage that develops following transplant)
- people with congenital heart defects, including those whose defects have been completely repaired with prosthetic materials (for the first six months after repair); those with “cyanotic” defects that have not been repaired or that have been partially repaired with shunts or conduits; those whose defects were repaired but who retain residual defects that prevent re-endothelialization (regrowth of normal cardiac lining) over prosthetic patches or devices
- persons with prosthetic cardiac valves or partially prosthetic valves
- individuals with a history of previous bacterial endocarditis
(Adapted from Wilson W, et al. Circulation. 2007;116[15]:1736-54 [see above])
Patients who have been diagnosed with heart murmurs, mitral valve prolapse, or other cardiac abnormalities will hopefully find reassurance in the American Heart Association’s newest guidelines. The necessity for taking antibiotics before undergoing dental procedures is apparently not as widespread as was previously believed.
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