OVERVIEW: What every practitioner needs to know about antibiotic prophylaxis for infective endocarditis

What is the American Heart Association's (AHA) rationale for changing their policies on antibiotic prophylaxis?

  • The AHA guideline evolved over 50 years.

  • The guidelines were published in an attempt to prevent life threatening infection.

  • The evidence to support these guidelines were based largely on case reports, limited data, and expert opinion.

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  • Previous guidelines were overly complicated, difficult to remember, ambiguous, and inconsistent.

  • The cumulative published data questioned the efficacy of antibiotic prophylaxis to prevent infective endocarditis (IE).

  • The frequency of viridans streptococcal bacteremia associated with dental procedures varies widely, reportedly from 30% to almost 100% of patients.

  • Viridans streptococcal bacteremia associated with the most common dental procedures, such as dental extraction (40%) or dental cleaning (35%) is similar to that reported with usual daily activities, such as brushing teeth or flossing teeth (20-68%), tooth picking (20-40%), or mastication (7-51%).

  • There are no significant reported differences between viridans streptococcal bacteremia associated with dental procedures and usual daily activities, either among frequency, magnitude, or duration of viridans streptococcal bacteremia.

  • Antibiotic prophylaxis is not recommended for patients with usual daily activities.

  • The cumulative exposure to bacteremia over time varies depending upon oral hygiene.

    One study estimated that the cumulative exposure to bacteremia over one month’s time was 6-30 minutes with a tooth extraction compared with 5370 minutes with usual daily activities such as mastication, tooth brushing, and dental flossing.

    The cumulative exposure to bacteremia over one year with daily activities is estimated to be 5.6 million times greater than for a single dental extraction.

  • The efficacy of antibiotic therapy to prevent bacteremia associated with dental procedures varies widely in published reports.

    Some show that amoxicillin effectively prevents bacteremia while others reported that amoxicillin was no more effective than controls.

    Similar results were published with the use of an oral cephalosporin or a macrolide.

These and other factors prompted the AHA to make substantitive changes in the recommendations for antibiotic prophylaxis for dental and other procedures.

What conditions carry a lifelong risk of infective endocarditis?

  • The risk of acquisition of IE for 100,000 patient years (the number of patients out of 100,000 who will develop endocarditis in one year)

    Mitral valve prolapse with audible cardiac murmur–52

    Congenital aortic stenosis–145

    Rheumatic valvular heart disease–380-440

    Prosthetic cardiac valve–308-383

    Previous IE–740

    Prosthetic valve replacement for prosthetic valve endocarditis–2160

  • Other studies have estimated the absolute risk of viridans streptococcal IE following a dental procedure as follows:

    General population–1/14 million

    Mitral valve prolapse–1.1 million

    Congenital heart disease–475,000

    Rheumatic heart disease–142,000

    Presence of prosthetic valve–114,000

    Previous IE–95,000

Clearly, many underlying cardiac conditions represent a lifelong risk of the acquisition of IE. However, there are no convincing published studies in humans which show that antibiotic prophylaxis given in association with a dental procedure prevents the development of IE. In addition, no convincing data have been published that links dental procedures with IE.

What are the major changes in the AHA guidelines for antibiotic prevention of infective endocarditis?

  • Bacteremia resulting from daily activities is much more likely to cause IE than bacteremia associated with a dental procedure.

  • An extremely small number of cases of IE might be prevented by prophylaxis for a dental procedure even if 100% effective.

  • Recommendations changed for antibiotic prophylaxis for dental procedure from risk of acquiringto risk from IE; if there is a benefit from antibiotic prophylaxis it should be reserved for patients with highest risk of adverse outcome from IE.

  • Prophylaxis is no longer recommended for forms of congenital heart disease not mentioned above including mitral valve prolapse.

  • Prophylaxis is no longer recommended for rheumatic heart disease.

  • The administration of prophylactic antibiotics solely to prevent endocarditis is no longer recommended for patients who undergo gastrointestinal (GI) or genitourinary (GU) tract procedures:

    The administration of prophylactic antibiotics solely to prevent endocarditis is not recommended for patients who undergo GI or GU procedures.

    Patients with the highest risk of adverse outcome from IE who have a pre-existing, underlying infection should receive targeted antibiotic therapy for treatment of infection prior to and during an invasive GI or GU procedure.

    Such therapy should include an antimicrobial agent effective against enterococci which are the most common cause of IE from a GI or GU tract source

Who should receive antibiotic prophylaxis for the prevention of infective endocarditis?

  • Should IE Prophylaxis Be Recommended for Patients With the Highest Risk of Acquisition of IE? NO

  • Should IE Prophylaxis Be Recommended for Patients With the Highest Risk of Adverse Outcome From IE? YES

  • The AHA recommends antibiotic prophylaxis for patients with the highest risk of an adverse outcome from infective endocarditis, and no longer recommends prophylaxis based on the risk of acquiring this infection.

  • Administration of antibiotic prophylaxis is not risk free and may promote emergence of resistant microorganisms most likely to cause IE.

  • The AHA identified the following groups of patients at highest risk of adverse outcome from IE and recommends antibiotic prophylaxis for dental procedures be administered only to these groups of patients:

    Prosthetic cardiac valve

    Previous infective endocarditis

    Congenital heart disease (CHD)—unrepaired cyanotic disease including those with shunts and conduits;

    repaired CHD with prosthetic material or device during the first six months up to the procedure;

    repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic valve.

    Cardiac transplantation recipients who develop cardiac valvulopathy

Which dental procedures would qualify for antibiotic prophylaxis in the high risk group of patients listed above?

The AHA and American Dental Association recommended antibiotic prophylaxis:

  • In all dental procedures and events that involve manipulation of gingival tissue or the periapical region of teeth or perforation of oral mucosa

What antibiotic regimens are recommended for prophylaxis of infective endocarditis and how should they be administered?

See the AHA guidelines for the prevention of infective endocarditis regimens for dental procedure (Table I).

Table In

WHAT'S THE EVIDENCE for specific management and treatment recommendations?

Wilson, WR, Taubert, KA, Gewitz, M, Lockhart, PB, Baddour, LM, Levison, M. “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. vol. 116. 2007. pp. 1736-1354.

“Prophylaxis against infective endocarditis”.

Richey, R, Wray, D, Stokes, T. “Prophylaxis against infective endocarditis: summary of NICE guidance”. MBI. vol. 336. 2008. pp. 770-1.

Habib, G, Hoen, B, Tomos, P, Thuny, F, Prendergast, B, Vilacosta, I. “Guidelines on the prevention, diagnosis, and treatment of infective endocarditis (new version 2009); the Task Force on the Prevention, Diagnosis, and Treatment of Infective Endocarditis of the European Society of Cardiology (ESC)”. Eur Heart J. vol. 30. 2009. pp. 2369-2413.

Lockhart, PB, Loven, B, Brennan, MT, Fox, PC. “The evidence base for the efficacy of antibiotic prophylaxis in dental practice”. J Am Dent Assoc. vol. 138. 2007. pp. 458-474.

Tleyjeh, IM, Steckelberg, JM, Murad, HS, Anavekar, NS, Ghomrawi, HM, Mirzoyev, Z. “Temporal trends in infective endocarditis: a population-based study in Olmsted Country, Minnesota”. JAMA. vol. 293. 2004. pp. 3022-3028.

Strom, BL, Abrutyn, E, Berlin, JA, Kinman, JL, Feldman, RS, Stolley, PD. “Dental and cardiac risk factors for infective endocarditis: a population-based case-control study”. Ann Intern Med. vol. 129. 1998. pp. 761-769.

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