Moreover, clinical practice guidelines can provide a founda- tion for other applications, such as performance measures, appropriate use criteria, and both quality improvement and clinical decision support tools. The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) have jointly produced guidelines in the area of cardiovascular disease since 1980. The ACCF/AHA Task Force on Practice Guide- lines (Task Force), charged with developing, updating, and revising practice guidelines for cardiovascular diseases and procedures, directs and oversees this effort. Writing committees are charged with regularly reviewing and evalu- ating all available evidence to develop balanced, patient- centric recommendations for clinical practice. Experts in the subject under consideration are selected by the ACCF and AHA to examine subject-speci c data and write guidelines in partnership with representatives from other medical organizations and specialty groups. Writing commit- tees are asked to perform a literature review; weigh the strength of evidence for or against particular tests, treatments, or procedures; and include estimates of expected outcomes where such data exist. Patient-speci c modi ers, comorbid- ities, and issues of patient preference that may in uence the choice of tests or therapies are considered. When available, information from studies on cost is considered, but data on ef cacy and outcomes constitute the primary basis for the recommendations contained herein. In analyzing the data and developing recommendations and supporting text, the writing committee uses evidence-based methodologies developed by the Task Force (1). The Class of Recommendation (COR) is an estimate of the size of the treatment effect considering risks versus bene ts in addition to evidence and/or agreement that a given treatment or procedure is or is not useful/effective or in some situations may cause harm. The Level of Evidence (LOE) is an estimate of the certainty or precision of the treatment effect. 