PO077 | BALANCING BLEEDING AND THROMBOSIS: SAFETY OF LOW-MOLECULAR-WEIGHT HEPARIN THROMBOPROPHYLAXIS IN PATIENTS WITH HEMOPHILIA UNDERGOING MAJOR SURGERY

S. Bergonzi^1|2|3, G. Murante^1|2|3, M. Capetta^1|2|3, F. Valeri^1|2, C. Dainese^1|2, A. Valpreda^3|4, R. Pastorino^3|4, F. Bocchi^3|4, B. Bruno^2|3, A. Borchiellini^1|2 | ¹Regional Centre for Hemorrhagic and Thrombotic Diseases, AOU Città della Salute e della Scienza, Turin, Italy; ²Division of Hematology, AOU Città della Salute e della Scienza, Università di Torino, Italy; ³Department of Molecular Biotechnology and Health Sciences, University of Turin, Italy; ⁴Central Laboratory Baldi and Riberi, AOU Città della Salute e della Scienza, Università di Torino, Italy

Background and Aims. In patients with hemophilia, the risk of venous thromboembolism (VTE) has historically been considered low. However, in the setting of major surgery, particularly orthopedic and oncologic procedures, this risk may become clinically relevant. Available evidence is limited and sometimes conflicting. The World Federation of Hemophilia guidelines (WFH, 3rd edition) recommend an individualized assessment of both thrombotic and bleeding risk, favoring mechanical thromboprophylaxis and reserving pharmacological prophylaxis for selected cases under adequate factor replacement and in patients without inhibitors. Similarly, the International Society on Thrombosis and Haemostasis (ISTH) highlights the low quality of available evidence and the need for a personalized approach. A recent systematic review reported a low incidence of VTE after major orthopedic surgery, but considerable heterogeneity in thromboprophylaxis use, reflecting the lack of consensus. In this context, we aimed to retrospectively evaluate the safety of pharmacological thromboprophylaxis with low-molecular-weight heparin (LMWH) in patients with hemophilia undergoing major surgery.
Methods. Medical records of 105 patients with moderate/severe hemophilia A or B followed at our center were retrospectively reviewed. Among these, 12 patients undergoing a total of 18 major surgical procedures received postoperative LMWH thromboprophylaxis. Data were verified and integrated through comparison with the rare diseases registry.
Results. All included patients had severe hemophilia A and received perioperative factor replacement therapy. Trough factor levels during the first three postoperative days were ≥14%, and ≥11% thereafter. Patient characteristics, type of surgery, and trough levels are reported in Table 1. A single bleeding event occurred in a patient undergoing intestinal reanastomosis for previous rectal adenocarcinoma (previously treated with LMWH prophylaxis without complications), who presented on postoperative day 4 with hematemesis and rectal bleeding, requiring LMWH discontinuation and transfusion support. No other major or minor bleeding events were observed. One patient developed a clinically evident VTE on postoperative day 8 despite LMWH thromboprophylaxis, in the presence of multiple risk factors (high-risk inherited thrombophilia and smoking). No additional clinically evident thromboembolic events were observed.
Conclusions. In a setting of limited and conflicting evidence, all patients underwent individualized assessment of thrombotic and bleeding risk. They received adequate factor replacement therapy and were monitored through factor levels. In this context, LMWH thromboprophylaxis appeared safe in the vast majority of cases. These findings support the feasibility of a personalized approach to pharmacological thromboprophylaxis in patients with hemophilia undergoing major surgery, although prospective studies are warranted to confirm its safety.