This systematic review will strive to determine which patients are most likely to benefit from a test, med- ication, device, or treatment strategy and to what degree. Criteria for commissioning an ERC and formal systematic review include: a) the absence of a current authoritative systematic review; b) the feasibility of defining the ben- efit and risk in a time frame consistent with the writing of a guideline; c) the relevance to a substantial number of patients; and d) the likelihood that the findings can be translated into actionable recommendations. ERC members may include methodologists, epidemiologists, healthcare providers, and biostatisticians. When a formal systematic review has been commissioned, the recom- mendations developed by the writing committee on the basis of the systematic review are marked with SR . Guideline-Directed Management and Therapy The term guideline-directed management and therapy (GDMT) encompasses clinical evaluation, diagnostic test- ing, and pharmacological and procedural treatments. For these and all recommended medication treatment regi- mens, the reader should confirm the dosage by review- ing product insert material and evaluate the treatment regimen for contraindications and interactions. The rec- ommendations are limited to medications, devices, and treatments approved for clinical use in the United States. Class of Recommendation and Level of Evidence The Class of Recommendation (COR) indicates the strength of the recommendation, encompassing the esti- mated magnitude and certainty of benefit in proportion to risk. The Level of Evidence (LOE) rates the quality of scientific evidence that supports the intervention on the basis of the type, quantity, and consistency of data from clinical trials and other sources (Table 1).P-4,P-6,P-8 Glenn N. Levine, MD, FACC, FAHA Chair, ACC/AHA Task Force on Clinical Practice Guidelines 1.1. Methodology and Evidence Review The recommendations listed in this clinical practice guide- line are, whenever possible, evidence-based. 