Implementing a method of heparinisation guided by activated clotting time (ACT), with a goal of 200–220 seconds, provides a “promising” increase in safety and may decrease risk of thromboembolic events, while not increasing bleeding complications. Presenting the findings of the pilot ACTION trial, Arno Wiersema (Amsterdam, The Netherlands) stated he and his colleagues “believe it is time to upgrade one of the foundations of vascular surgery to optimise patient care and to prove that ACT-guided heparinisation results in far fewer thromboembolic complications.”
“The success of open and endovascular arterial interventions depends on a delicate balance between coagulation and anticoagulation”, said Wiersema in the first Aortic Podium 1st Session at Charing Cross (CX) yesterday. “Ever since its introduction in clinical practice 70 years ago, unfractionated heparin has been administered during these non-cardiac arterial procedures to prevent thromboembolic complications. A major disadvantage of this use of heparin is that it could increase bleeding complications, as extensive surveys have shown that almost all vascular surgeons and interventional radiologists use a standardised bolus of 5,000IU of heparin during non-cardiac arterial procedures.” This is in sharp contrast to cardiac interventions, noted Wiersema, where heparin is used in higher dosages. “As surprising as it may seem, only one randomised controlled trial (in 1996) has been performed on the benefit of heparin, comparing a group with heparin to a group without heparin as prophylactic antithrombotic.” The fact that no other study has since been performed on this subject despite the wide uptake of heparinisation is, to Wiersema and his colleagues, reportedly “astonishing”. For this reason, the ACTION trial was designed, to examine the benefits of heparinisation guided by ACT, with the hypothesis that less thromboembolic complications and no increase in bleeding complications would be observed.
“The final goal of ACT to strive for”, commented Wiersema, “was set at 200 to 220 seconds. To reach those ACT values, a starting bolus of 100 units per kilogram was used and additional doses were set at 60 or 30 units, depending on the actual ACT.” He added that a protocol was instituted for the use of protamine at the end of the procedure, to decrease the incidence of bleeding complications.
In terms of the results, “ACT-guided heparinisation ensured the vast majority of the patients of adequate and safe anticoagulation. Almost all patients reached an ACT of more than 200 seconds after the first bolus.” The mean dose of heparin needed to maintain this optimal anticoagulation was roughly twice the bolus of 5,000 units. While the incidence of bleeding complications was not increased, a “promising trend” of decrease in thromboembolic complications was observed, falling from 11% to 6%.
Wiersema emphasised the importance of establishing the added value of ACTguided heparinisation “once and for all”, stating: “We are on the verge of receiving a large grant to perform an international randomised controlled trial. This trial is starting in The Netherlands, Hamburg (Germany) and Copenhagen (Denmark), and we are more than happy to include other major vascular centres around the world. We need only 748 patients in five years to prove a reduction for the combined incidence of thromboembolic complications and mortality from 19% to 11%. If this method is proven to be better during open aortic aneurysm repair, it can be directly incorporated for all our other procedures.”
Concluding, Wiersema said “the ACTION pilot showed that ACT-guided heparinisation increases patient safety and looks very promising as a method to decrease thromboembolic complications, without a relevant rise in bleeding complications.”