Introduction: Percutaneous coronary intervention (PCI) may be associated with Thrombotic complications. Unfractionated heparin (UFH) is a potent and preferable antithrombotic agent during this procedure. Activated clotting time (ACT) is a good assay for accurate titration of UFH during PCI. The aim of this study was to evaluate ACT levels 10 minutes after administration of 100U/kg IV heparin and determining its associated factors.

Methods: This study was performed in Madani hospital, Tabriz, Iran between January 2013 to January 2014. One hundred and two patients candidates for elective PCI were enrolled in the study. Data including demographic and risk factors were collected.

Result: The range of ACT was between 165 to 750 seconds (mean 319.8 seconds), 52 (51%) patients had ACT levels lower than 300sec and 12 (11.8%) patients had ACT levels between 300 to 350 seconds which is known optimal range and 38 (37.2%) cases had ACT levels above this value. Major risk factors had no effect on ACT value, but there was a trend to higher levels with increasing age (P= 0.06). There was no difference in the rate of major or minor bleeding with respect to ACT levels (P= 0.52). There was a trend to higher rate of minimal bleeding in those with ACT> 350 sec (P= 0.06).

Conclusion: Weight based UFH injection may result in suboptimal anticoagulation during the procedure. Routine ACT measurement may be necessary to ascertain adequate anticoagulation. Major risk factors had no effect on ACT level and it was not associated with the rate of bleeding.