European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery, 18 3 2025, Pages S1078-5884(25)00690-2 Activated Clotting Time Guided Heparinisation during Open Abdominal Aortic Aneurysm Repair (ACTION-1): A Randomised, Multicentre, Single Blind, Superiority Trial. Jongkind V, Steunenberg TAH, Roosendaal LC, Hoebink M, Blankensteijn JD, Koelemay MJW, Kropman RHJ, Zeebregts CJ, van Schaik J, Heyligers JMM, Geelkerken RH, Pierie MEN, Reijnen MMPJ, Lemson SM, Hoencamp R, Teijink JAW, Steinbauer MG, Hissink RJ, Debus S, Buscher HCJL, Fioole B, van Dieren S, Wiersema AM, collaborators
Objective
The optimal dosage of intravenous unfractionated heparin and the role of monitoring its effect using activated clotting time (ACT) to prevent thrombo-embolic complications (TECs) during open abdominal aortic aneurysm (AAA) repair are uncertain. This trial aimed to compare ACT guided heparinisation with a single dose of 5 000 international units (IU) of heparin.
Methods
This was a multicentre, randomised controlled, single blinded, superiority trial (NCT04061798). Patients undergoing elective open AAA repair were randomly assigned (1:1) to receive either ACT guided heparinisation with a dose of 100 IU per kilogram with a target duration of 200 seconds or a single heparin bolus of 5 000 IU as a control group. The primary efficacy outcome was the combined incidence of TECs and all cause death at 30 days. The safety outcome was the incidence of bleeding complications. ACT measurements were performed using the same device to limit variability.
Results
The trial was ended prematurely due to futility after inclusion of 294 patients. After randomisation, 149 patients received ACT guided heparinisation and 145 patients were assigned to the control group. The primary outcome occurred in 34 patients (22.8%) in the ACT group vs. 37 patients (25.5%) in the control group (absolute difference -2.7%, 95% confidence interval [CI] -12.5 - 7.1%). Bleeding complications (absolute difference 9.2%, 95% CI -1.8 - 20.2%) and deaths (absolute difference 7.9%, 95% CI 2.3 - 13.6%) were higher in the ACT group. No difference was found in the incidence of TECs (absolute difference -5.4%, 95% CI -15.0 - 4.2%).
Conclusion
In patients undergoing open AAA repair, heparinisation with 100 IU/kg and ACT monitoring at a target of 200 seconds did not reduce the primary efficacy outcome and increased the risk of peri-operative bleeding compared with a single bolus of 5 000 IU. Additionally, increased mortality was observed.
