Fighting Endocarditis One Antibiotic at a Time

Volume 19, Issue 4

Just about any pharmacist who has practiced in a community setting has dispensed an antibiotic for prophylaxis against infectious endocarditis for patients undergoing invasive dental procedures. In fact, most of us have probably never questioned the rationale for such a prescription. The idea behind antibiotic prophylaxis is that patients undergoing invasive dental procedures can seed bacteria into their bloodstream, and this transient bacteremia could lead to infective endocarditis in those at risk.

In this week’s issue of Talking Therapeutics, we explore recent history for the use of antibiotic prophylaxis against infective endocarditis, and discuss a recent trial evaluating the impact of this maneuver.

Point 1: Evidence for Prophylaxis Has Been Very Weak

So weak, in fact, that the 2008 guidelines for the United Kingdom (NICE guidelines) recommended to cease the routine prescribing of antibiotics for prophylaxis against infective endocarditis. As a result of these guidelines, the rates of prescriptions in the United Kingdom plummeted.

Unfortunately, rates of infective endocarditis started to climb slowly after publication of these guidelines, in the United Kingdom as well as in the United States and Canada.

Equally unfortunate is that while these temporal trends insinuate that antibiotic prophylaxis against infective endocarditis is effective, that is simply not a scientific conclusion. A more robust analysis is required to prove that hypothesis.

Point 2: Recent Evidence Affirms What We’ve Known All Along

A paper published recently in the Journal of the American College of Cardiology evaluated the effectiveness of antibiotic prophylaxis against infective endocarditis in an insurance database of 7,951,972 US subjects. The main study findings are as follows:

• Most cases of infective endocarditis occurred within 4 weeks of an invasive dental procedure.
• For those at high risk for endocarditis, there was a significant temporal association between infection and invasive dental procedures in the preceding 4 weeks (OR: 2.00; 95% CI: 1.59-2.52; P = .002).
• This relationship was strongest for dental extractions (OR: 11.08; 95% CI: 7.34-16.74; P < .0001) and oral-surgical procedures (OR: 50.77; 95% CI: 20.79-123.98; P < .0001).
• Antibiotic prophylaxis was associated with a significant reduction in infective endocarditis incidence following invasive dental procedures (OR: 0.49; 95% CI: 0.29-0.85; P = .01).

Overall, this study provides robust support for the current 2017 AHA/ACC guidelines, which recommend antibiotic prophylaxis for those at high risk of infective endocarditis from dental procedures. I would expect the evidence strength of the current recommendation to improve in subsequent guidelines as a result of this important paper.