(996) Argatroban Dosing in a Patient With Heparin-Induced Thrombocytopenia Undergoing Vascular Surgery

Introduction: Heparin-induced thrombocytopenia (HIT) is an antibody-mediated thrombocytopenia that can paradoxically precipitate thrombosis. The most common alternative anticoagulants to heparin employed for patients undergoing cardiovascular surgery are the direct thrombin inhibitors bivalirudin and argatroban. However, little data or literature exist regarding the optimal dosing technique for patients undergoing a large non-cardiac vascular surgery. We present a case of a patient with a history of HIT undergoing fenestrated endovascular aortic repair (FEVAR) using argatroban for anticoagulation.

Description: A 59-year-old male with a history of Stanford Type A aortic dissection repaired by thoracic endovascular aortic repair (TEVAR) presented to the vascular surgery clinic for annual imaging follow-up with complaints of worsening low back pain at night. CT angiogram revealed enlarging thoracoabdominal aortic aneurysm and he was scheduled for FEVAR. Given his history of immunoassay-positive HIT and the need for intraoperative anticoagulation, argatroban was used intraoperatively. We utilized a bodyweight-based dose similar to well-described literature for percutaneous coronary intervention (PCI) with cardiopulmonary bypass (CPB), which was a 350 µg/kg bolus followed by an infusion beginning at 25µg/kg/min titrated based on goal activated clotting time (ACT) of 300-450 seconds intraoperatively. With eventual goal ACT below 300s prior to closure, the infusion rate was titrated down in 5µg/kg/min increments until eventually stopped, but ACT was consistently above 450s and could not be lowered below 300s before case conclusion. The case concluded without bleeding complications and the patient made a full recovery.

Discussion: Due to uncertainties surrounding the administration of intraoperative argatroban, it is important to determine a dosing strategy for large non-cardiac vascular cases with high bleeding risk. Ideal body weight dosing, as opposed to measured bodyweight, may be explored. Utilizing the dosing for PCI with CPB may have been an overestimation, and ACT control may be better achieved utilizing the American Society of Hematology guidelines for PCI without CPB, which involves infusion at 2-5µg/kg/min 30-60min prior to surgery for patients without hepatic dysfunction, with goal ACT 200-300s.