Heparin Management and Coagulation in Acute Aortic Dissection Surgery: A Randomised Controlled Trial

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.

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.

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.

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).

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.