Intraoperative Unfractionated Heparin Unresponsiveness during Endovascular Repair of a Ruptured Abdominal Aortic Aneurysm following Administration of Andexanet Alfa for the Reversal of Rivaroxaban.

The authors describe a case of unfractionated heparin (UFH) unresponsiveness in the operating room secondary to reversal of rivaroxaban with coagulation factor Xa (recombinant) inactivated-zhzo (andexanet alfa). A 70-year-old man with a known 4.5- to 5.0-cm abdominal aortic aneurysm and atrial fibrillation managed with rivaroxaban presented with severe right-sided flank pain radiating to the left side of his abdomen. Computed tomography-angiography on arrival demonstrated a left retroperitoneal hematoma and a suspected ruptured abdominal aortic aneurysm. He received andexanet alfa to reverse rivaroxaban prior to an emergent endovascular aneurysm repair. During surgery, he received a total of 14,000 units (167 units/kg) of UFH with minimal changes in activated clotting time (132-144 sec; baseline 135 sec [reference range 74-137 sec]). This case highlights the potential complications of using UFH anticoagulation following reversal of factor Xa inhibitors with andexanet alfa and underscores the importance of peri-procedural anticoagulation planning. For patients who require intra-operative anticoagulation, providers should consider anticoagulation reversal with prothrombin complex concentrate instead of andexanet alfa or administration of a parenteral direct thrombin inhibitor, such as argatroban or bivalirudin during the surgical procedure.