In addition, the present statement includes a new section, Surgical Therapy. This work addresses primarily IE in adults; a more detailed review of the unique features of IE in children is available in another statement from the AHA Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease.20 The committee also published state- ments on endocarditis that complicates electrophysiological (pacemakers, intracardiac defibrillators),21 ventricular assist, and other nonvalvular cardiac devices.22 Evidence-Based System for Diagnostic and Treatment Recommendations The writing group was charged with the task of performing an evidence-based assessment of the data and providing a class of recommendation and a level of evidence for each recom- mendation according to the American College of Cardiology/ AHA classification system (http://circ.ahajournals.org/ manual/manual_IIstep6.shtml). The class of recommendation is an estimate of the size of the treatment effect, considering risks versus benefits, in addition to evidence or agreement that a given treatment or procedure is or is not useful or effective or in some situations may cause harm. The level of evidence is an estimate of the certainty or precision of the treatment effect. The Writing Group reviewed and assessed the strength of evidence supporting each recommendation with the level of evidence ranked as A, B, or C according to the specific defini- tions included in Table 1. For certain conditions for which data were either unavailable or inadequate, recommendations were based on expert consensus and clinical experience, and these were ranked as Level of Evidence C. The scheme for the class of recommendations and levels of evidence is summarized in Table 1, which also provides suggested phrases for writing recommendations within each class of recommendation. 