ACT measured at presentation offered limited predictive value for early IRA patency in ST-segment elevation myocardial infarction (STEMI). Published in the International Journal of Cardiology, the study examined whether ACT could signal early TIMI 2–3 flow in patients pretreated with UFH.

The study included 898 adults with STEMI who received 5000 units of UFH within 120 minutes of symptom onset. Median ACT values differed only slightly between those with TIMI 0–1 flow and those achieving TIMI 2–3 flow. Higher ACT, the presence of diabetes, shorter heparin-to-catheterization intervals, and absence of hypertension were independently associated with early flow restoration.

Despite these associations, ACT showed limited predictive performance (AUC 0.612) and did not reliably identify patients with early reperfusion.

These findings suggest that ACT alone cannot accurately guide expectations of early IRA patency in STEMI, and that broader clinical variables may be needed to refine early reperfusion assessment.