On the basis of the data from Steckelberg and Wilson91 and others,2 it is clear that the underlying conditions discussed above represent a lifetime increased risk of acquisition of IE compared with individuals with no known underlying cardiac condition. Accordingly, when utilizing previous AHA guide- lines in the decision to recommend IE prophylaxis for a patient scheduled to undergo a dental, GI tract, or GU tract procedure, healthcare providers were required to base their decision on population-based studies of risk of acquisition of IE that may or may not be relevant to their specific patient. Furthermore, practitioners had to weigh the potential efficacy of IE prophylaxis in a patient who may neither need nor benefit from such therapy against the risk of adverse reaction to the antibiotic prescribed. Finally, healthcare providers had to consider the potential medicolegal risk of not prescribing IE prophylaxis. For dental procedures, there is a growing body of evidence that suggests that IE prophylaxis may prevent only an exceedingly small number of cases of IE, as discussed in detail above. Cardiac Conditions Associated With the Highest Risk of Adverse Outcome From Endocarditis Endocarditis, irrespective of the underlying cardiac condition, is a serious, life-threatening disease that was always fatal in the preantibiotic era. Advances in antimicrobial therapy, early recognition and management of complications of IE, and improved surgical technology have reduced the morbidity and mortality of IE. Numerous comorbid factors, such as older age, diabetes mellitus, immunosuppressive conditions or therapy, and dialysis, may complicate IE. Each of these comorbid conditions independently increases the risk of adverse outcome from IE, and they often occur in combina- tion, which further increases morbidity and mortality rates. Additionally, there may be long-term consequences of IE. 