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Revised Guidelines for Endocarditis Prophylaxis: Resetting the Bar

New guidelines are based on the premise that few endocarditis cases will be prevented with antibiotic prophylaxis.

Despite a lack of clinical evidence, previous practice guidelines have advised fairly broad use of antibiotics to prevent the devastating consequences of infective endocarditis. One of the principles driving the development of prior American Heart Association (AHA) guidelines was that antibiotic prophylaxis was considered effective for people undergoing dental, gastrointestinal (GI), or genitourinary (GU) procedures. However, since the 1997 revisions, the validity of this principle has been questioned. Although endocarditis causes significant morbidity and mortality, the condition is uncommon even among individuals with certain cardiac conditions: For example, the absolute risk for endocarditis in those with mitral valve prolapse is approximately 1 per 1.1 million dental procedures. Thus, the AHA has released simplified new guidelines founded on the premise that only a few endocarditis cases will be prevented with antibiotic prophylaxis.

Endocarditis arises when certain blood-borne pathogens interact with sites of endocardial cell damage in conjunction with the patient’s immune response. Some bacterial types are more apt than others to adhere to the disrupted endothelial surface. Enterococci are particularly likely to seed the bloodstream following procedures such as dental manipulations; thus, the new guidelines focus on these bacteria.

Antibiotic prophylaxis for dental procedures including biopsies, suture removal, and placement of orthodontic bands is recommended for patients with:

• Prosthetic heart valves
  
• Previous infective endocarditis
  
• Certain forms of congenital heart disease
  
• Valve abnormalities after cardiac transplant
  

Patients do not need antibiotic prophylaxis if they are undergoing:

• Dental procedures and have mitral valve prolapse
  
• Bronchoscopy (unless the respiratory mucosa is incised)
  
• GI or GU procedures (except for the above high-risk cardiac conditions when infection is present; enterococcal coverage is then recommended)
  
• Other procedures previously identified as not needing antibiotics (vaginal delivery, hysterectomy, ear or other body piercing, and tattooing)
  

Recommended antibiotics include oral amoxicillin or intramuscular or intravenous ampicillin given in one dose 30 to 60 minutes before the procedure or within 2 hours after the procedure. Alternatives for patients who are allergic to penicillins or ampicillin include oral cephalexin, clindamycin, azithromycin, or clarithromycin, or non-oral cefazolin, ceftriaxone, or clindamycin.

Comment: Even these updated recommendations were based on consensus rather than well-established clinical findings. Thus, the guidelines will almost certainly be revised again. Nonetheless, the reasoning behind the changes was well thought out, and antibiotic prophylaxis is now recommended only for the highest-risk patients undergoing specific dental interventions. Clinicians should find these guidelines easier to follow yet still must weigh treatment decisions individually.

— Marian C. Limacher, MD

Published in Journal Watch Women's Health September 13, 2007

Citation(s):

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 Apr 19; [e-pub ahead of print]. (http://dx.doi.org/10.1161/CIRCULATIONAHA.106.183095)