Thank you for your inquiry regarding CMS996v5: Appropriate Treatment for ST-Segment Elevation Myocardial Infarction (STEMI) Patients in the Emergency Department (ED). It is the measure’s intent to only capture events occurring in the ED encounter, not outside of it. As noted in the response to your initial inquiry, a patient with a STEMI diagnosis may be captured in the measure in two ways, as indicated by the measure logic definition below found in version 5 of the measure’s HTML file [ https://ecqi.healthit.gov/sites/default/files/ecqm/measures/CMS996v5.html#d1e649 ]. ED Encounter with STEMI Diagnosis "ED Encounter with Encounter Diagnosis of STEMI"   union "ED Encounter with Diagnosis of STEMI" ED Encounter with Encounter Diagnosis of STEMI "ED Encounter During MP" EDEncounter   with EDEncounter.diagnoses EncounterDiagnosis     such that EncounterDiagnosis.code in "STEMI" ED Encounter with Diagnosis of STEMI "ED Encounter During MP" EDEncounter   with ["Diagnosis": "STEMI"] DxSTEMI     such that DxSTEMI.prevalencePeriod starts during EDEncounter.relevantPeriod An ED encounter with STEMI diagnosis is defined as either (i) a STEMI diagnosis coded during the encounter, which corresponds to the “ED Encounter with Encounter Diagnosis of STEMI” logic definition and uses the “Encounter, Performed” diagnoses attribute, or (ii) a STEMI diagnoses pulled from a claim, problem list, or other source within the EHR where the prevalence period starts (i.e., the onset dateTime of the diagnosis) during the ED encounter. The latter corresponds to the “ED Encounter with Diagnosis of STEMI” logic definition and uses the “Diagnoses” data type. Please note that STEMI diagnoses are identified using the codes in the STEMI value set (OID: 2.16.840.1.113883.3.3157.4017). For context, the Quality Data Model (QDM) provides the language that defines the criteria for clinical quality measurement. In other words, it defines the type of data required, rather than the source of the data or how data is represented in real-world systems. It was designed to support heterogeneous data sources, enable human abstraction, and provide flexibility across systems. Per the QDM 5.6, the “Encounter, Performed” diagnoses attribute is intended to capture ALL diagnoses addressed during the encounter. If the ED initially suspected STEMI, and the patient was treated as such during the ED encounter, the patient would be counted in the measure denominator. Additionally, the “Diagnosis” data type represents a practitioner’s identification of a patient’s disease, illness, injury, or condition by means of examination, diagnostic test results, patient history, and/or family history. For more information regarding “Diagnosis” and “Encounter, Performed” QDM datatypes and their attributes, please see the QDM 5.6: https://ecqi.healthit.gov/sites/default/files/QDM-v5.6-508.pdf .