Quality measures may then be promoted to the status of per- formance measures as supporting evidence becomes available. Gregg C. Fonarow, MD, FACC, FAHA Chair, ACC/AHA Task Force on Performance Measures 3 In the summer of 2015, the Task Force convened the writing committee to begin the process of revising the existing set of performance measures for adult patients hospitalized with ST-Elevation and Non ST-Elevation Myocardial Infarction (STEMI and NSTEMI, respectively), that was last updated in The writing committee was charged with the task of developing new measures to benchmark and improve the qual- ity of care for patients with STEMI and NSTEMI. All the measures included in the measure set are briefly summarized in Table 1, which provides information on the measure number, title, care setting, attribution, and domain. The detailed measure specifications (available in Appendix A) provide not only the information included in Table 1, but also more detailed information including the measure description, numerator, denominator (including denominator exclusions and exceptions), rationale for the measure, guideline recom- mendations that support the measure, measurement period, and sources of data. The writing committee has developed a comprehensive STEMI/NSTEMI measure set that includes 24 total measures of which 17 are performance measures and 7 are quality mea- sures (as reflected in Table 1 and Appendix A). The writing committee believes that implementation of this measure set by healthcare providers, physician practices, and hospital sys- tems will enhance the quality of care and likely improve out- comes of patients with STEMI and NSTEMI. 1.1. Scope of the Problem Acute myocardial infarction (AMI) is a frequent cause of hospital admission in the United States and is associated with significant short- and long-term mortality and mor- bidity. 