Problem definition/Rationale: Heparin is used during open abdominal aortic aneurysm (AAA) surgery to reduce thrombo-embolic complications (TEC): myocardial infarction, stroke and peripheral embolic events. But heparin increases blood loss causing harm for the patient. Heparin has an unpredictable effect in the individual patient. The effect can be measured by the Activated Clotting Time. ACT measurement in open AAA repair should be introduced to ensure the individual patient of safe, tailor-made anticoagulation. An ACT of 250 seconds should be reached. A RCT has to prove that ACT guided heparinization results in less TEC than a standardized bolus of heparin, the current gold standard. The ACT guided heparinisation should also decrease the mortality caused by TEC. ACT guided heparinisation leads to higher doses of heparin during operation. This should not result in significantly more bleeding complications of importance.
Objective: Does ACT guided heparinization decreases TEC during open AAA surgery?
Study design: International multi-center randomised controlled trial.
Patient population: Patients undergoing open AAA surgery, AAA originating below the SMA.
Investigational product and comparator: Heparin LEO®. ACT guided dosing compared to a single dose of 5.000 IU heparine.
Outcome variables and assessment: All thrombo-embolic, death and bleeding complications, PROMS and QALY. All costs of care.
Analysis: Intention to treat principle. Absolute risk differences with 95% confidence intervals. Level of significance set at a p-value < 0.05.
Sample size AAA: 624 patients.
Economic evaluation: Cost-effectiveness analysis based on total costs per TEC and death within 12 months and a reduction of 50% of TEC.