Activated clotting time

ACT

Overview
The activated clotting time (ACT) was introduced during the 1970s as a test to monitor the administration and subsequent reversal of unfractionated heparin (UFH) during coronary artery bypass graft surgery. Currently the test is widely used in the cardiac catheterization laboratory to monitor the adequacy of UFH dosing. The unit of measure is in seconds.

Titration of UFH dosing based upon the ACT
While practice patterns in Europe are such that a large single dose of UFH is often administered for a percutaneous coronary intervention (PCI) (150 Units/per Kg), in the United States, lower doses of UFH (35 to 70U/kg depending upon the operator) are administered, and subsequent doses of UFH are titrated based upon the ACT. In the absence of a glycoprotein 2b3a inhbitor, the target ACT is usually 250 to 300 seconds. If a glycoprotein 2b3a inhibitor has been administered, the target ACT is lower, at 200 to 250 seconds.

Relationship of the ACT to clinical outcomes
Despite the aggressive use of ACT monitoring, there is scant data to relate the peak ACT to efficacy or bleeding outcomes in the setting of PCI.