These guidelines, based on systematic methods to evaluate and classify evidence, provide a cornerstone of quality cardio- vascular care. In response to reports from the Institute of Medicine1,2 and a mandate to evaluate new knowledge and maintain relevance at the point of care, the ACC/AHA Task Force on Clinical Practice Guidelines (Task Force) modified its methodology.3 5 The relationships between guidelines, data standards, appro- priate use criteria, and performance measures are addressed Intended Use Practice guidelines provide recommendations applicable to patients with or at risk of developing cardiovascular dis- ease. The focus is on medical practice in the United States, but guidelines developed in collaboration with other organi- zations may have a broader target. Although guidelines may inform regulatory or payer decisions, they are intended to improve quality of care in the interest of patients. Evidence Review Guideline Writing Committee (GWC) members review the lit- erature; weigh the quality of evidence for or against particular tests, treatments, or procedures; and estimate expected health outcomes. In developing recommendations, the GWC uses evidence-based methodologies that are based on all available Literature searches focus on randomized controlled trials (RCTs) but also include registries, nonrandomized comparative and descriptive studies, case series, cohort stud- ies, systematic reviews, and expert opinion. Only selected ref- erences are cited. The Task Force recognizes the need for objective, indepen- dent Evidence Review Committees (ERCs) that include meth- odologists, epidemiologists, clinicians, and biostatisticians who systematically survey, abstract, and assess the evidence to address key clinical questions posed in the PICOTS format (P=population, I=intervention, C=comparator, O=outcome, Practical considerations, including time and resource constraints, limit the ERCs to evidence that is relevant to key clinical questions and lends itself to sys- tematic review and analysis that could affect the strength of corresponding recommendations. 