The 1997 guidelines were revised in 2008.
They are summarized here: http://www.chp.edu/CHP/Antibiotic+Guidelines
Wilson et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation: 2007, 116(15);1736-54