For certain conditions for which inadequate data are available, recommendations are based on expert consensus and clinical experience and ranked as LOE C. When recommenda- tions at LOE C are supported by historical clinical data, appropriate references (including clinical reviews) are cited if available. For issues for which sparse data are available, a survey of current practice among the clinicians on the writing group is the basis for LOE C recommendations, and no references are cited. The schema for COR and LOE is summarized in Table 1, which also provides suggested phrases for writing recommen- dations within each COR. A new addition to this methodology is separation of the Class III recommendations to delineate whether the recommendation is determined to be of no benefit or is associated with harm to the patient. In addition, in view of the increasing number of comparative effectiveness studies, comparator verbs and suggested phrases for writing recommendations for the comparative effectiveness of one treatment/strategy with respect to another for COR I and IIa, LOE A or B only. In view of the advances in medical therapy across the spectrum of cardiovascular diseases, the Task Force has designated the term guideline-directed medical therapy (GDMT) to represent optimal medical therapy as defined by ACCF/AHA guideline (primarily Class I) recommended ther- apies. This new term, GDMT, will be used herein and throughout all future guidelines. Because the ACCF/AHA practice guidelines address pa- tient populations (and healthcare providers) residing in North America, drugs that are not currently available in North America are discussed in the text without a specific COR. 