News Release

Study details use, misuse of antibiotics to prevent heart infections

Peer-Reviewed Publication

Beth Israel Deaconess Medical Center

Most physicians giving proper recommendation before dental work

BOSTON,June 27, 2000 -- Despite simplified guidelines published widely several years ago, many people with certain pre-existing heart conditions are not getting correct advice about taking antibiotics to prevent potentially life-threatening infections.

"About 25 percent of people who don't need antibiotics are getting them, and about 40 percent of people who should be taking them are not," says cardiologist Warren Manning, M.D., section chief of non-invasive cardiac imaging in the cardiovascular division at Beth Israel Deaconess Medical Center. "Both numbers are too high."

Manning and his colleagues report their findings in the July 5 issue of the weekly Journal of the American Medical Association.

Since 1955, the American Heart Association has recommended antibiotics to prevent a rare but potentially fatal infection of the heart's inner lining or heart valves, known as bacterial or infective endocarditis. During dental cleanings, for example, bacteria from the mouth can enter the bloodstream and attach themselves to heart valves. About three-fourths of people who become infected have pre-existing heart conditions, such as leaky, artificial or significantly thickened valves.

Three years ago, updated heart association guidelines simplified the dosing regimens. Moderate or high risk patients should take a single dose of antibiotic one hour before certain dental cleanings or other procedures in which bleeding is common. Also, the new guidelines recommend an ultrasound of the heart, or echocardiogram, to identify heart abnormalities that put people at risk.

Curious about how the updated guidelines are working, Manning and his colleagues followed up with 218 patients who had received echocardiograms at Beth Israel Deaconess Medical Center. Most patients reported hearing back from their primary care physicians about antibiotic prophylaxis use. Nearly 90 percent of high-risk patients were instructed to take antibiotics for certain procedures, which Manning calls acceptable.

Of the largest group -- moderate-risk patients -- who probably should be taking preventative antibiotics, only about 60 percent reported receiving instructions to take antibiotics from their doctors. Among the low-risk patients who don't need antibiotics, about 25 percent incorrectly were advised to take them.

Additionally, Manning found that 13 percent of patients instructed to take antibiotics instead chose not to take them.

"The good news is that our study suggests most patients are complying with their physicians' recommendations," says Manning, also an associate professor of medicine and radiology at Harvard Medical School. "However, many physicians appear to be lax about prescribing antibiotics for moderate-risk conditions and overly zealous about prescribing antibiotics for low-risk patients. Physicians need to be more aware of indications for antibiotic prophylaxis. We believe that clarification of the guidelines will also improve compliance."

Manning and his colleagues are conducting a larger follow-up study to learn if adding a specific recommendation regarding prophylaxis to the echocardiographic report improves compliance.

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For more information on the American Heart Association guidelines for bacterial endocarditis, see http://www.americanheart.org.

Media contacts:
Warren Manning, cardiology
617-667-2192, wmanning@caregroup.harvard.edu
or Carol Cruzan Morton, Beth Israel Deaconess communications
617-975-6150, cmorton@caregroup.harvard.edu
or Bill Schaller, Beth Israel Deaconess communications
617-975-6152, bill_schaller@caregroup.harvard.edu

EDITOR'S NOTE: Beginning June 29, Dr. Manning is available for telephone interviews only. A patient undergoing an echocardiogram may be available before June 28.



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