The rationale for the new infective endocarditis guidelines.

Given the terrible consequences of infectious endocarditis (IE), it has become a time-honored strategy to use antibiotics as prophylaxis against IE for invasive procedures associated with bacteremia with endocarditis-causing organisms. The evidence supporting this approach has come predominantly from animal models of endocarditis or observational human studies. Prompted by the desire to realistically assess the evidence base for a health policy with global implications and against the backdrop of increasing microbial resistance to antibiotics, a careful review of all available data regarding the effectiveness of prophylaxis against IE was performed. This reanalysis prompted a new set of recommendations for IE prevention, published in 2007 by the American Heart Association, which represented a marked divergence from 50 years of prior publications. The rationale and underpinning evidence for the new recommendations are reviewed here, with an eye to the gaps in the available evidence and the need for future research.