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New Guidelines for Prevention of Endocarditis

Now that the AHA has updated its guidelines, many fewer patients should receive antibiotic courses before routine procedures.

The focus of Journal Watch "Top Stories" generally is original research, not practice guidelines. This year we make an exception with the American Heart Association’s new guidelines on prevention of endocarditis, which represent a major shift in practice. For many clinical entities, multiple organizations elaborate competing clinical guidelines in the U.S., but for prevention of endocarditis, the AHA’s guideline — last updated in 1997 — essentially stands alone (Journal Watch Jun 12 2007).

Prophylaxis is now recommended for only four high-risk conditions — prosthetic valves, previous endocarditis, certain types of congenital heart disease, and cardiac transplantation with valvulopathy. For patients with these conditions, prophylaxis should be given before only the following procedures: dental procedures that involve manipulation of gingival tissue or periapical regions of the teeth or that involve perforation of oral mucosa, incision or biopsy of respiratory-tract mucosa, and surgery on infected skin or musculoskeletal structures. Amoxicillin (2 g, given orally 30–60 minutes before the procedure) is recommended; alternatives are listed for patients with penicillin allergy or those who cannot tolerate oral medications.

Two important changes are particularly relevant to everyday practice. First, endocarditis prophylaxis is no longer recommended before gastrointestinal (GI) and genitourinary (GU) procedures; however, for patients with high-risk cardiac conditions who have established GI or GU infections (e.g., enterococcal urinary infection), one should attempt to eradicate the infection prior to any invasive procedure. Second, prophylaxis is no longer recommended for patients with acquired cardiac valvular disease or mitral valve prolapse, even if mitral regurgitation is present.

What prompted these changes? Researchers have long noted limitations in the evidence supporting endocarditis prophylaxis. No randomized trials have been conducted, and retrospective studies have yielded mixed results. Moreover, cumulative exposure to bacteremia from daily oral activities (e.g., chewing, flossing, brushing) is far greater than exposure from occasional dental procedures. Experts now believe that the potential harms from millions of antibiotic courses in low-risk patients outweigh any benefits.

This new guideline should dramatically lower antibiotic prescribing for endocarditis prophylaxis. In fact, many patients who shouldn’t have qualified for endocarditis prophylaxis even under the 1997 version (e.g., those with innocent systolic murmurs) have been receiving prophylaxis. The new guideline affords an opportunity for primary care physicians to educate such patients. Finally, resistance from dentists should be eased by the American Dental Association’s approval of this guideline.

— Allan S. Brett, MD

Published in Journal Watch General Medicine December 28, 2007