The American Heart Association 2007 endocarditis prophylaxis guidelines: A compromise between science and common sense

Abstract

The new American Heart Association (AHA) guidelines on antimicrobial prophylaxis for endocarditis published in 2007 represent a major step in the evolution of these guidelines (1). Antimicrobial prophylaxis is recommended for use in fewer patients and for a smaller number of invasive procedures. Because antimicrobial prophylaxis for endocarditis has been a standard and routine part of the management of patients with heart disease, and because its use involves several different specialties, such as cardiology, infectious disease and dentistry, it is noteworthy that these guidelines were not received with the same rancour that greeted similar guidelines from the British Society for Antimicrobial Chemotherapy (BSAC), which were published one year earlier (2). “Defying explanation” was the headline of the letter by the British Congenital Cardiac Association and the British Cardiovascular Society expressing concerns about the BSAC guidelines (3). We believe that the new AHA guidelines were more readily accepted because they have previously been circulated to and endorsed by scientific bodies, including the American Dental Association, the Infectious Diseases Society of America and the Pediatric Infectious Diseases Society, and because there is an increasing awareness that medical practice needs to be evidence-based. Nonetheless, there are still concerns regarding these new guidelines from physicians and patients, despite the fact that the 2007 guidelines were built on the foundation of previous guidelines. In this brief commentary, we summarize the major changes since the 1997 guidelines and provide suggestions on incorporating these changes into clinical practice. The provision of antimicrobial therapy to prevent bacterial endocarditis has long been considered an essential part of the management of persons with cardiac lesions, because the consequences of bacterial endocarditis in either a native or prosthetic valve can be grave. Since the initial inception of the AHA recommendations for antibiotic regimens for the prevention of infective endocarditis in 1955, these guidelines have gradually been evolving, as nicely summarized in the 2007 recommendations (1,4). The previous AHA guidelines, published in 1997, contained what was considered to be a significant change in endocarditis prophylaxis recommendations for high-risk procedures: the provision of a single 2 g oral amoxicillin dose 1 h before a dental or respiratory procedure (5). This was heralded as a significant modification because it eliminated the postprocedure dose. Furthermore, cardiac lesions were categorized into low, moderate and high risk for endocarditis. Antimicrobial prophylaxis was recommended for patients at moderate or high risk. The low-risk lesions were considered to be of such negligible consequence that antimicrobial prophylaxis was not recommended (5).