Key result
Heparin-dose response guidance shows no benefit over ACT guidance in limiting thrombin generation during bypass.
Why the study?
The optimal anticoagulation strategy during cardiopulmonary bypass for acute type A aortic dissection surgery remains uncertain due to profound consumptive coagulopathy and perioperative transfusion needs.
Does heparin-dose response (HDR) guided anticoagulation improve suppression of thrombin generation compared to activated clotting time (ACT) guided anticoagulation in patients undergoing emergent surgery for acute type A aortic dissection?
RCT (n=26)
partially blinded
1:1, stratified by organ dysfunction and preoperative anticoagulation
No
Does heparin-dose response (HDR) guided anticoagulation improve suppression of thrombin generation compared to activated clotting time (ACT) guided anticoagulation in patients undergoing emergent surgery for acute type A aortic dissection?
Absolute Event Rate: 333% vs -92%
p-value: p=0.31
Current standard anticoagulation strategies, whether guided by HDR or ACT, are insufficient in suppressing thrombin generation during emergent surgery for acute type A aortic dissection.
Neither heparin protocol suppresses thrombin generation in acute aortic dissection repair; confirms persistent coagulopathy and supports trials of alternative strategies.
BACKGROUND: Acute type A aortic dissection remains a life-threatening condition characterised by profound consumptive coagulopathy and perioperative transfusion requirements. The optimal anticoagulation strategy during cardiopulmonary bypass remains uncertain. OBJECTIVES: To assess baseline coagulation and compare the impact of two standard anticoagulation strategies on thrombin generation and clinical outcomes in patients undergoing emergent surgery for acute type A aortic dissection. PATIENTS/METHODS: In this single-centre, partially blinded, randomised controlled trial, patients were allocated 1:1 to heparin-dose response (HDR) or activated clotting time (ACT) guided anticoagulation. Randomisation was stratified by organ dysfunction and preoperative anticoagulation. Primary endpoint was change in prothrombin fragment 1+2 (F1+2) from baseline to heparin reversal after cardiopulmonary bypass. Secondary endpoints included coagulation markers, bleeding, transfusion, and clinical outcomes up to 90 days. RESULTS: Between December 2022 and September 2024, 26 patients were randomised (HDR= 14; ACT= 12). Both groups demonstrated marked baseline consumptive coagulopathy with ongoing intraoperative thrombin generation. Despite baseline differences in F1+2, the primary endpoint did not differ significantly (median change HDR: 333 [IQR 654] vs. ACT: -92 pmol/L [IQR 1984], p = 0.31). Post hoc baseline-adjusted ANCOVA sensitivity analysis of log-transformed change (n = 25) showed a 14% lower fold-increase in HDR compared with ACT (HDR/ACT ratio 0.86, 95% CI 0.63-1.17; p = 0.32). Secondary endpoints were comparable, except for a lower protamine-to-heparin ratio in HDR group (0.51 vs 0.75; p < 0.001). CONCLUSIONS: Thrombin generation was insufficiently suppressed by either anticoagulation protocol. Exacerbation of preoperative consumptive coagulopathy highlights the insufficiency of current anticoagulation strategies in acute aortic dissection.
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Eschen et al. (2026) conducted an RCT in Acute type A aortic dissection (n=26). Heparin-dose response (HDR) guided anticoagulation vs. Activated clotting time (ACT) guided anticoagulation was evaluated on Change in prothrombin fragment 1+2 (F1+2) from baseline to heparin reversal after cardiopulmonary bypass (p=0.31). Heparin-dose response guided anticoagulation did not significantly differ from activated clotting time guidance in changing prothrombin fragment 1+2 levels (median 333 vs -92 pmol/L; p=0.31).
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