P eriprocedural anticoagulation is recommended during percutaneous coronary intervention (PCI) to prevent thrombus forming on the wires, balloon, and catheters. 1 Unfractionated heparin (UFH) remains widely used in this indication (≈60% of patients with non-ST-segment-elevation myocardial infarction [NSTEMI] undergoing PCI in the United States received UFH, according to data from the recent National Cardiovascular Data Registry).2 Because UFH has a narrow therapeutic window and its effect is poorly predictable, 3 guidelines from the United States recommend UFH dosing guided by measurement of activated clotting time (ACT) in the catheterization laboratory. 4 This recommendation is based on data from retrospective analyses showing an association between ACT values and thrombotic 5,6 or bleeding 7 outcomes. However, these observational studies are subject to confounding, and they were conducted before the availability of modern antiplatelet therapy and, for some studies, before the widespread use of coronary stents. Conversely, more recent analyses have found no association between ACT and the risks of bleeding 8 or thrombotic 9,10 events. Whether ACT is correlated with periprocedural thrombotic or bleeding events in the modern era of PCI remains unclear.Background-Activated clotting time (ACT) is widely used to guide unfractionated heparin dosing during percutaneous coronary intervention. However, its value in predicting complications is controversial in the modern era. We sought to examine the relationship between ACT and outcomes in non-ST-segment-elevation acute coronary syndrome patients.
Methods and Results-In the Fondaparinux With Unfractionated Heparin During Revascularization in Acute Coronary Syndromes(FUTURA/OASIS-8) trial, 2026 patients with non-ST-segment-elevation acute coronary syndrome treated with fondaparinux 2.5 mg/d and undergoing percutaneous coronary intervention were randomized to low-dose unfractionated heparin (50 U/ kg) or standard-dose unfractionated heparin (85 U/kg or 60 U/kg with glycoprotein IIb/IIIa inhibitors, with ACT guidance).No difference was shown for major bleeding and there was a trend toward a reduction in ischemic events with standard-dose unfractionated heparin. To clarify the additional value of ACT guidance, we analyzed with logistic modeling peri-percutaneous coronary intervention outcomes according to peak ACT as a linear function. A threshold effect was then investigated. No linear correlation was found between ACT and thrombotic or bleeding events. In patients not receiving planned glycoprotein IIb/IIIa inhibitors, a significant increase in rates of death, myocardial infarction, and target vessel revascularization was identified in patients with an ACT≤300 s (4.86% versus 2.78%; adjusted odds ratio, As the FUTURA/OASIS-8 trial compared 2 different heparin regimens, the additional value of ACT guidance remains unclear. The aims of the present analysis were therefore to determine the relationship between the UFH dose administered and the peak ACT and to determine the ...