If a patient comes into the ED and a STEMI evolves AFTER 90 minutes of arrival and the primary coding for this patient is marked as STEMI-Present On Arrival (Yes) because the STEMI occurs within the first 24 hours (for example, if the STEMI evolved by hour 4), This will cause the patient to fall out of the measure for OP-40 because they were coded as a STEMI but PCI was not performed within 90 minutes for this patient, fibrinolytics were not administered within 30 minutes, and transfer to acute care was not performed within 45 minutes because it was not warranted at that time. However, if one of those required interventions was completed within the timeframe of actual identification of the STEMI, rather than the metric asks for arrival of STEMI patient to ED, the patient would pass the measure. Please advise how we can identify and/or code these patients appropriately so that we can follow appropriate coding rules, while simultaneously meet the measure requirements. As it stands, the metric seems to be based on ED arrival time and not on STEMI identification timing. Are you able to provide any examples or education to support and/or assist our facility in understanding the metric further. We have studied the Specifications at length and have not found how to address late presenting STEMI patients.