Thank you for your inquiry regarding CMS996: Appropriate Treatment for ST-Segment Elevation Myocardial Infarction (STEMI) Patients in the Emergency Department (ED). We interpret the intent of your inquiry is to determine if an encounter will be captured in the STEMI measure if only the relevantPeriod startTime attribute is captured in EHR documentation, and not the stopTime. The measure logic uses the relevantPeriod attribute for several QDM datatypes. For an ED encounter with a STEMI diagnosis to be captured in the measure denominator, the relevantPeriod of the “Encounter, Performed”: “Emergency Department Evaluation and Management Visit” datatype must end during the one-year measurement period. Therefore, the stopTime of the relevantPeriod (or the time the encounter ended) must be documented in the EHR. The inquiry’s attachment also highlights the Intubation or Mechanical Circulatory Assist Device Procedure During the ED encounter or within 24 hours of the ED encounter denominator exclusion criterion. The startTime (the time the procedure begins) or relevantdateTime (the time the procedure is performed if it occurs at a single point in time) attributes for the “Procedure, Performed”: Endotracheal Intubation and “Procedure, Performed:” “Insertion or Replacement of Mechanical Circulatory Assist Device” datatypes must start during the ED encounter or start 24 hours or less before the start of the ED encounter to meet the exclusion. The exclusion can still be fulfilled even if the stopTime of the procedures’ relevantPeriod is not documented in the EHR. Additionally, the measure captures three potential numerators for patients that arrive to the ED with a STEMI diagnosis: PCI procedure within 90 minutes of ED arrival, fibrinolytic therapy in 30 minutes of ED arrival, or discharge to PCI-capable acute care facility within 45 minutes of ED arrival. To be captured in the first numerator criteria, we recommend that the EHR capture the point in time the PCI was deployed (i.e., balloon inflation) per the clinical guidelines. A “Procedure, Performed”: “Percutaneous Coronary Intervention” relevantPeriod stopTime (or the time the procedure ends) is not required in EHR documentation for this numerator criterion to be fulfilled. Furthermore, a “Medication, Administered: “Fibrinolytic Therapy” relevantPeriod stopTime (or the time a single medication administration event ends) is not required in EHR documentation for the second numerator criterion to be fulfilled. Lastly, although the Discharge Disposition”: “Discharge To Acute Care Facility” QDM datatype in the third numerator criteria does not utilize the relevantPeriod attribute, there are some functions used to define the third numerator criterion in which relevantPeriod stopTime is required. For more information regarding relevantPeriod attribute usage in the measure, please see the most recent specifications for the CMS996v6 STEMI measure posted to the eCQI Resource Center [ https://ecqi.healthit.gov/sites/default/files/ecqm/measures/CMS996v5.html ], and work with your EHR vendor to ensure appropriate documentation of relevantPeriod attributes.