We are seeking clarification on the logic applied to the denominator exclusion for the OP-40 STEMI eCQM, specifically regarding the timing of mechanical circulatory assist procedures such as IABP.
 

The measure description states that the exclusion applies if the procedure "occurs 24 hours or less before the start of the ED encounter or during the ED encounter."
However, the technical logic appears to define the exclusion window as "during the ED encounter or within 24 hours of the ED encounter start."
This raises two questions:
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Which interpretation is correct?

• Should the exclusion window be interpreted as before the ED encounter (i.e., up to 24 hours prior), or after the ED encounter start (i.e., within 24 hours following ED arrival)?
• Does the ED class change to Observation affect the logic?
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  If a patient transitions from ED to Observation or inpatient status, does this impact the logic’s ability to correctly identify the ED encounter window for exclusion purposes?
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  We encountered a case where an IABP was placed within the 24-hour window following ED arrival, and the patient was not excluded from the denominator. We want to ensure our interpretation aligns with CMS expectations and that our logic implementation is accurate.
   
  Thank you for your guidance and support.