Thank you for your inquiry regarding CMS996v5: Appropriate Treatment for ST-Segment Elevation Myocardial Infarction (STEMI) Patients in the Emergency Department (ED). Any STEMI diagnosis coded during the ED encounter will be included in the measure. The QDM does not prescribe the source of diagnosis data in the EHR. Diagnoses may be found in a patient’s problem list, encounter diagnosis list, claims data, or other sources within the EHR. A patient with a STEMI diagnosis may be captured in the measure in two ways, as indicated in the measure logic’s ‘ED Encounter with STEMI Diagnosis’ definition, found below. ED Encounter with STEMI Diagnosis "ED Encounter During MP" EDEncounterinMP     where (exists (["Diagnosis": "STEMI"] DxSTEMI       where DxSTEMI.prevalencePeriod starts during EDEncounterinMP.relevantPeriod))     or (exists( EDEncounterinMP.diagnoses EncounterDiagnosis       where EncounterDiagnosis.code in "STEMI" )) First, a STEMI diagnosis can be pulled directly from the ED encounter if a STEMI diagnosis was coded during the encounter. Second, the patient can have a diagnosis pulled from a claim, problem list, or other source within the HER, as long as the prevalencePeriod of the STEMI diagnosis started during the ED encounter relevantPeriod. PrevalencePeriod is an attribute of the “Diagnosis” datatype and signifies the onset dateTime to abatement dateTime of the STEMI diagnosis. RelevantPeriod is an attribute of the “Encounter, Performed”: “Emergency Department Evaluation and Management Visit” datatype and signifies the startTime that the encounter began (admission time) to the stopTime that the encounter ended (discharge time).