Prevention of Endocarditis For >5 decades, scientific organizations and public health- care policy groups around the world have advocated for the administration of antibiotic drugs for prophylaxis against IE. This recommendation, however, was never firmly grounded on well-designed, appropriately powered randomized clini- cal trials, and thus, scientific challenges to the concept emerged. These challenges were abetted by epidemio- logical facts that became apparent as well. Only 20% of endocarditis cases have actually been related to a preceding invasive procedure for which antibiotic drugs would have been recommended, and only 50% of cases of IE occur in people with an existing cardiac condition for which antibi- otic prophylaxis would have been prescribed. Thus, even the core epidemiology of IE was at variance with the existing, traditional guidelines. Moreover, increasing concern devel- oped in recent years that the dispensing of millions of doses of antibiotic drugs for a weakly supported rationale con- tributes to the development of antibiotic resistance. These issues were the impetus for extensive topical reviews per- formed by the AHA, the European Society of Cardiology, the British Society for Antimicrobial Chemotherapy, and other leading groups that all concluded that sharply limiting the use of antibiotic drugs for prophylaxis against IE was appropriate and timely. The 2007 AHA guideline on Prevention of Infective has become a widespread standard and is similar to the European Society of Cardiology statement. The British guidelines (NICE) carried the revisions furthest, with recommendations to eliminate prophylactic antibiotic drugs altogether for all patients under any circumstances. 