Antibiotic Before Oral Surgery Spares Endocarditis

The strongest evidence yet to support clinical guidelines that recommend that people at high risk of endocarditis, such as those who’ve had previous episode the disease or who have a prosthetic cardiac valve, should take antibiotics before they have a tooth pulled or other types of oral surgery, comes from a new study that used two methodologies.

But it also pointed out that two-thirds of the time they aren’t getting that type of antibiotic coverage.

The researchers conducted a cohort study of almost 8 million retirees with employer-paid Medicare supplemental prescription benefits and dental benefits, then conducted a case-crossover study of 3,774 people from the cohort who’d been hospitalized with infectious endocarditis (IE) and who had invasive dental procedures. The bottom line is that the study supports the clinical guidelines from the American Heart Association and the European Society of Cardiology that recommend antibiotic prophylaxis (AP) before dental procedures for patients at high-risk of IE.

Likewise, lead author Martin Thornhill, MBBS, BDS, PhD, said in an interview, the findings also suggest that existing guidelines in the United Kingdom, which recommend against AP in these patients, “should be reconsidered.”

Those AHA and ESC guidelines, however, are “based on no good quality evidence,” said Thornhill, professor of translational research in dentistry at the University of Sheffield (England) School of Clinical Dentistry. “Other studies have looked at this, but we’ve done the largest study that has shown the clear association between invasive dental procedures and subsequent development of infective endocarditis.”

In the entire cohort of 7.95 million patients, 3,774 had cases of IE that required hospitalization. The study defined highest risk of IE as meeting one of these six criteria: a previous case of IE; a prosthetic cardiac valve or a valve repair that used prosthetic material; cyanotic congenital heart disease; palliative shunts or conduits to treat CHD; or a congenital heart defect that had been fully repaired, either by surgery or a transcatheter procedure, with prosthetic material or device – the latter within 6 months of the procedure.

Moderate IE risk included patients who had rheumatic heart disease, nonrheumatic valve disease or congenital valve anomalies—including mitral valve prolapse or aortic stenosis—or hypertrophic cardiomyopathy.

Risk Classification and Poor Compliance

Highest-risk patients had significantly higher rates of IE a month after a dental procedure than lower-risk groups: 467.6 cases per 1 million procedures vs. 24.2 for moderate risk and 3.8 for low or unknown risk. A subanalysis found that the odds of IE were significantly increased for two specific dental procedures: extractions, with an odds ratio of 9.22 (95% confidence interval [CI], 5.54-15.88; P < .0001); and other oral surgical procedures, with an OR of 20.18 (95% CI, 11.22-37.74; P < .0001).

The study also found that 32.6% of the high-risk patients undergoing dental procedures got AP. “Clearly that shows a low level of compliance with the guidelines in the U.S.,” Thornhill said. “That’s something that needs to be addressed.”

The study was unique in that it used both a population cohort study and the case-crossover study. “It didn’t matter which of the two methods we used; we essentially came to the same result, which I think adds further weight to the findings,” Thornhill said.

This may be the best evidence to support the guidelines that clinicians may get. While the observational nature of this study has its limitations, conducting a randomized clinical trial to further validate the findings would be “logistically impossible,” he said, in that it would require an “absolutely enormous” cohort and coordination between medical and dental databases covering thousands of lives. An RCT would also require not using AP for some patients. “It’s not ethical to keep somebody off of antibiotic prophylaxis when there’s such a high risk of death and severe outcomes,” Thornhill said.

Ann Bolger, MD, emeritus professor of medicine at the University of California, San Francisco, and coauthor of an editorial comment on the study, said in an interview that this study is noteworthy not only for its dual methodology, but for the quality of the data that matched patients at high risk for IE with prescription and dental records. “The fact that they were able to have those details in enough granularity that they knew whether a dental procedure was likely to meet the criteria for these more invasive exposures really broke it open from my perspective,” she said.

She called the low compliance rate with AHA guidelines “one of the most sobering points of this,” and said it should put clinicians on notice that they must do more to educate and engage with high-risk patients. “The lines of communication here are somewhat fraught; it’s a little bit of a hot potato,” she said. “It’s a really great communications opportunity to get the provider’s attention back on this. You’re a cardiologist; you have to have this conversation when you see your patient with a prosthetic valve or who’s had endocarditis every time they come in. There’s a whole litany, and it takes 3 minutes, but you have to do it.”

The study received funding from Delta Dental of Michigan Research Committee and Renaissance Health Service Corp., and Thornhill received support from Delta Dental Research and Data Institute for the study. Bolger participated in the 2007 and 2021 AHA statements on AP to prevent IE.

This article originally appeared on, part of the Medscape Professional Network.

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