Current issues in prevention of infective endocarditis.

Prevention of infective endocarditis continues to concern health care providers in many specialties. The well-known lack of primary clinical trials in this area is not expected to change. Therefore, the evolution of recommendations and practice must be based on theoretic considerations and continuing assessment of secondary sources of information. Recent developments include a report of 52 cases in which antibiotic prophylaxis for infective endocarditis was attempted but appeared to fail. Most of these patients had undergone dental procedures after oral penicillin prophylaxis, with subsequent development of streptococcal endocarditis. In two thirds, the organism was sensitive to the antibiotic used. Notably, the most common underlying cardiac lesion among these patients was mitral valve prolapse. However, two recent independent analyses have concluded that providing endocarditis prophylaxis for all patients with mitral valve prolapse during procedures that might cause bacteremia would not be cost-effective. This is primarily because mitral valve prolapse is common and endocarditis is relatively rare, resulting in an adverse risk-benefit ratio. Parenteral prophylaxis for mitral valve prolapse might even cause a net loss of life from anaphylaxis. On the other hand, for the individual patient or physician, the reassurance provided by attempted prophylaxis with oral penicillin can be purchased at low cost and low risk. Very few cases of infective endocarditis have been reported after gastrointestinal and other endoscopic procedures; most of these do not need antibiotic coverage. Prophylactic antibiotics should be restricted to those situations in which both the procedure and the underlying cardiac condition seem to pose significant risk, for example, endoscopic sclerotherapy of esophageal varices in patients with prosthetic heart valves. Newly revised recommendations have been issued by the Medical Letter, the American Heart Association, and the American Dental Association. These regimens are shorter and simpler than earlier versions.