The Dental Procedure-Infective Endocarditis Link Controversy Continues

By Michael H. Crawford, MD

Professor of Medicine, Lucy Stern Chair in Cardiology, University of California San Francisco

SYNOPSIS: Infective endocarditis was more common with dental surgery or tooth extractions in the preceding four weeks in high-risk patients. Researchers abrogated this risk with antibiotic prophylaxis before the procedure.

SOURCE: Thornhill MH, Gibson TB, Yoon F, et al. Antibiotic prophylaxis against infective endocarditis before invasive dental procedures. J Am Coll Cardiol 2022;80:1029-1041.

Despite recommendations for antibiotic prophylaxis for certain dental procedures in patients at high risk of infective endocarditis (IE), the link between dental procedures and IE has never been established. Thornhill et al examined a large U.S. healthcare population database, which included dental procedures that occurred from 2000 until 2015, to identify any temporal association between dental procedures and IE, and whether antibiotic prophylaxis affected IE incidence.

The authors used a case crossover design, during which the four months preceding IE was compared to the preceding 12 months; patients were their own controls. Among almost 8 million patients, 3,774 were hospitalized with IE, 34% of whom were considered at high risk for IE (current American Heart Association guideline-recommended antibiotic prophylaxis candidates — e.g., prosthetic valves or repair material present, cyanotic congenital heart disease), 22% were moderate risk (native valve disease or hypertrophic cardiomyopathy), and 44% were low risk.

A time course analyses showed IE usually occurred within four weeks of a dental procedure for those at high risk (odds ratio [OR], 2.00; 95% confidence interval [CI], 1.59-2.52; P = 0.002). The risk of developing IE within 30 days of a dental procedure was significantly higher for extractions (OR, 9.22; 95% CI, 5.54-15.88; P < 0.0001) or dental surgery (OR, 20.18; 95% CI, 11.22-36.74; P < 0.0001) in high-risk patients. The authors also observed risk for extractions in moderate-risk patients (OR, 3.25; 95% CI, 1.61-6.46; P < 0.03) and low-risk patients (OR, 2.41; 95% CI, 1.44-3.95; P = 0.02).

Researchers also noted an association with low-risk patients and dental surgery (OR, 3.74; 95% CI, 1.79-7.15; P = 0.02). However, only high-risk patients seemed to benefit from antibiotic prophylaxis when used before extractions (IE OR, 0.013; 95% CI, 0.03-0.34; P < 0.0001) and surgical procedures (OR, 0.09; 95% CI, 0.01-0.35; P = 0.002). The authors concluded there is a significant temporal association between tooth extractions and oral surgery with IE in high-risk patients. There was a significant association between antibiotic prophylaxis and a lower rate of IE following these procedures.

COMMENTARY

The frequent occurrence of oral streptococci in IE cases and the 30% one-year mortality rate of IE patients drove the idea that prior dental work could cause IE and antibiotic prophylaxis administered before such procedures could prevent it. However, because of a lack of relevant data, concern for antibiotic resistance, and pushback from dentists, the recommendation for antibiotic prophylaxis before dental work in high-risk patients for IE has been abandoned in the United Kingdom.

Thornhill et al demonstrated antibiotic prophylaxis can lower the risk for high-risk patients. The data in moderate- and low-risk patients are less conclusive, in that only extractions showed a higher risk of IE, and antibiotic prophylaxis did not abrogate this risk. However, clinicians still cannot exclude the possibility that the condition that produced the need for an extraction or surgery is the culprit rather than the procedure itself. In this regard, it is interesting that teeth cleaning did not increase the risk of IE, perhaps because dental hygiene is better among those who undergo routine cleanings.

There were limitations to this study. The database included patients with dental care in their health plan. Patients with less robust or no dental insurance could experience different outcomes. In addition, the authors only considered streptococcal IE. The rise in this infection the United States could be attributed to more injection drug use and the presence of more intravascular medical devices in an aging population. Although there are clear limitations to using administrative data, this study may render any future randomized controlled trial (RCT) that includes high-risk patients unethical. However, a RCT that includes low- or moderate-risk patients may be feasible, but would require a huge population. Finally, comparative antibiotic effectiveness was not feasible because 75% of patients who were prophylaxed received amoxicillin.

Considering the seriousness of IE, it is remarkable only about one-third of patients who underwent invasive dental procedures in this study received antibiotic prophylaxis. This nihilistic approach seems unwise now, considering the results of this study. This is an opportunity for physician education. In my practice, I prophylax all high-risk patients as well as moderate-risk patients with what is considered more than mild valvular regurgitation along with patients who have been diagnosed with hypertrophic cardiomyopathy.