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November 10, 2008

 

Endocarditis Prophylaxis: Re-examining the Evidence

By: Michael W. Rich, MD

The American Heart Association (AHA) first published guidelines for the prevention of bacterial endocarditis in 1955 (1), and from 1957 to 1997, the guidelines were updated eight times. These guidelines have reflected current consensus opinion on the cardiovascular conditions which pose a significant risk for developing endocarditis, the procedures for which the risk of bacteremia is sufficiently high to warrant antibiotic prophylaxis, and the selection of an antibiotic regimen designed to minimize the risk of infection. Over the past 50 years, the guidelines have become widely accepted by clinicians and dentists and have been considered the "standard of care" for appropriately selected patients undergoing dental work and various other invasive procedures. From the beginning, however, the guidelines were based almost exclusively on expert opinion rather than on evidence from clinical studies that confirmed antibiotic prophylaxis is indeed effective in reducing the risk of endocarditis without exposing large numbers of patients to the small but nevertheless very real risk of serious adverse reactions to antibiotics, including anaphylaxis and, rarely, death.

In recent years, the "conventional wisdom" on antibiotic prophylaxis has come under increased scrutiny, and several studies have questioned the value of this intervention. In 2004, for example, a Cochrane review of penicillin for bacterial endocarditis in patients undergoing dental procedures concluded that "there is no evidence about whether penicillin prophylaxis is effective or ineffective against bacterial endocarditis in people at risk who are about to undergo an invasive dental procedure." The authors of the review further stated that "there is a lack of evidence to support published guidelines in this area. It is not clear whether the potential harms and costs of penicillin administration outweigh any beneficial effect." (2)

In light of these growing concerns, in 2007, after a hiatus of 10 years, the AHA released new guidelines for the prevention of infective endocarditis (3). Based on a reassessment of available evidence, the authors of the revised guidelines drew several important conclusions that significantly impacted their recommendations (see Table 1). As a result, the new guidelines represent a major departure from previous recommendations in that both the cardiac conditions warranting prophylaxis (see Table 2) and the procedures for which prophylaxis is recommended (see Table 3) have been markedly restricted. For example, patients with mitral valve prolapse (with or without a heart murmur) no longer require prophylaxis prior to dental procedures, nor do patients undergoing routine diagnostic gastrointestinal or urological procedures, including endoscopy and cystoscopy. As a result, the revised guidelines greatly simplify the "rules" for prophylaxis for primary care physicians, cardiologists, gastroenterologists, urologists and other surgeons, dentists, and, not least importantly, patients themselves.

Early reaction to the revised guidelines has been somewhat mixed. Some clinicians and patients have, understandably, been reluctant to depart from longstanding and presumably authoritative recommendations that have become engrained in the culture of medical practice, and concern has been expressed that failure to provide prophylaxis might expose patients to an undue risk of contracting endocarditis. However, in my estimation, these fears are unfounded since, as noted in the new guidelines, the cumulative risk of endocarditis resulting from bacteremia related to routine daily activities, especially tooth brushing, is substantially higher than the risk associated with dental work and most medical procedures. Thus, it makes more sense to emphasize maintenance of optimal oral health than to provide antibiotic prophylaxis prior to dental procedures. In my view, the new guidelines serve to rectify what in the past has been an overly aggressive use of antibiotic prophylaxis, which has not been shown to reduce the risk of endocarditis or to improve patient outcomes. I therefore strongly support the new guidelines and believe that they should be widely disseminated. Clinicians should be encouraged to rapidly adopt these new recommendations, which really represent more of a "course correction" than a radical change in policy.

Author

Michael W. Rich, MD
St. Louis, MO

Disclaimer

The views and opinions expressed are those of the author and do not necessarily state or reflect those of the National Guideline Clearinghouse (NGC), the Agency for Healthcare Research and Quality (AHRQ), or its contractor, ECRI Institute.

Potential Conflicts of Interest

Dr. Rich declares no potential conflicts of interest with respect to this commentary.

References

  1. Jones TD, Baumgartner L, Bellows MT, et al. Committee on Prevention of Rheumatic Fever and Bacterial Endocarditis, American Heart Association. Prevention of rheumatic fever and bacterial endocarditis through control of streptococcal infections. Circulation 1955;11:317-20.
  2. Oliver R, Roberts GJ, Hooper L. Penicillins for the prophylaxis of bacterial endocarditis in dentistry. Cochrane Database Syst Rev 2004;2:CD003813.
  3. Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. Circulation 2007;116:1736-54.

 

Table 1
Primary Reasons for Revision of the Infective Endocarditis Prophylaxis Guidelines

  • Infective endocarditis is much more likely to result from frequent exposure to random bacteremias associated with daily activities than from bacteremia caused by a dental, gastrointestinal tract, or genitourinary tract procedure.
  • Prophylaxis may prevent an exceedingly small number of cases of infective endocarditis, if any, in individuals who undergo a dental, gastrointestinal tract, or genitourinary tract procedure.
  • The risk of antibiotic-associated adverse events exceeds the benefit, if any, from prophylactic antibiotic therapy.
  • Maintenance of optimal oral health and hygiene may reduce the incidence of bacteremia from daily activities and is more important than prophylactic antibiotics for a dental procedure to reduce the risk of infective endocarditis.

Source: Adapted from Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. Circulation 2007;116:1736-54.

 

Table 2
Cardiac Conditions Associated with the Highest Risk of Adverse Outcome from Endocarditis for Which Prophylaxis with Dental Procedures is Reasonable

  • Prosthetic cardiac valve or prosthetic material used for cardiac valve repair
  • Previous infective endocarditis
  • Congenital heart disease (CHD)*
    • Unrepaired cyanotic CHD, including palliative shunts and conduits
    • Completely repaired congenital heart defect with prosthetic material or device, whether placed by surgery or by catheter intervention, during the first 6 months after the procedure**
    • Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endothelialization)
  • Cardiac transplantation recipients who develop cardiac valvulopathy

*Except for the conditions listed above, antibiotic prophylaxis is no longer recommended for any other form of CHD.

**Prophylaxis is reasonable because endothelialization of prosthetic material occurs within 6 months after the procedure.

Source: Adapted from Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. Circulation 2007;116:1736-54.

 

Table 3
Procedures for Which Antibiotic Prophylaxis is Reasonable

  • Antibiotic prophylaxis is reasonable for all dental procedures that involve manipulation of gingival tissue or periapical region of teeth or perforation of oral mucosa only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from infective endocarditis (Table 2).
  • Antibiotic prophylaxis is reasonable for procedures on respiratory tract or infected skin, skin structures, or musculoskeletal tissue only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from infective endocarditis (Table 2).

Procedures for Which Antibiotic Prophylaxis is Not Recommended

  • Dental procedures
    • Anesthetic injection through non-infected tissue
    • Dental x-rays
    • Placement, adjustment, or removal of orthodontic or prosthodontic appliances
    • Shedding of deciduous teeth
    • Bleeding from trauma to the lips and oral mucosa
  • Gastrointestinal procedures, including endoscopy of the upper gastrointestinal tract and colonoscopy
  • Genitourinary procedures, including cystoscopy, hysterectomy, and vaginal delivery
  • Tattooing

Source: Adapted from Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis. Guidelines from the American Heart Association. Circulation 2007;116:1736-54.

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