Purpose: Despite the American Heart Association's (AHA) recommendations for antibiotic prophylaxis to prevent infective endocarditis, no controlled clinical evidence exists for the effectiveness of this intervention. The purpose of this case-control study was to determine whether antibiotic prophylaxis for a dental procedure reduces the risk of infective endocarditis in persons with high-risk cardiac lesions.
Patients and methods: Cases consisted of eight subjects with high-risk lesions (six mitral, one aortic, one uncorrected tetralogy) whose first-time, native-valve infective endocarditis occurred within 12 weeks of a dental procedure and was diagnosed between 1980 and 1986. For each case subject, three control subjects were chosen from patients who underwent echocardiographic evaluation between 1980 and 1986, and who were matched for the specific high-risk lesion and age. Use of antibiotic prophylaxis, which was determined by interviews with patients and supplemented by the dentists, was defined as antibiotic taken both before and after the dental procedure.
Results: Antibiotic prophylaxis was used by only one of eight (13%) case subjects compared with 15 of 24 (63%) control subjects, for an odds ratio of 0.09, which is clinically impressive (indicating 91% protective efficacy) and statistically significant (p = 0.025).
Conclusion: Although this report does not specifically assess the value of antibiotic prophylaxis for the current AHA recommendations, the use of antibiotic prophylaxis in persons with high-risk cardiac lesions is supported by the magnitude of protective efficacy observed in this study.