Bivalirudin in Patients with HIT or Clinically Suspected HIT.
Authors: Ramirez Luz M. , Carman Teresa L. , Begelman Susan M. , AlMahameed Amjad , Joseph Douglas , Kashyap Vikram S. , White David A. , Andersen-Harris Krista , Bartholomew John R. 
Published: April 2020

Abstract
Background: Heparin-induced thrombocytopenia (HIT) is a serious complication of heparin and low molecular weight heparin therapy. All patients with HIT need treatment with a non-heparin anticoagulant. In the United States, two direct thrombin inhibitors are FDA-approved for patients with HIT: lepirudin and argatroban. Lepirudin is eliminated by the kidneys and is not ideal in patients with renal dysfunction. Argatroban is metabolized in the liver and should be used with caution in patients with hepatic insufficiency. Bivalirudin is approved for use in percutaneous coronary intervention and is under study for use in patients with HIT undergoing cardiopulmonary bypass. Bivalirudin has a short half-life (25 min) and is 20% metabolized via the kidneys and 80% by proteolytic cleavage.
Methods: We are reporting our experience from a retrospective review of 42 patients with clinically suspected, laboratory-confirmed, or previously diagnosed HIT treated with bivalirudin.
Results: Thirteen patients had a history of HIT; 9 were admitted for an interventional procedure or surgery. In 29 (69%) patients, HIT was suspected because of a fall in platelet count and/or thrombosis in the setting of current or recent heparin therapy. HIT was confirmed in 15/29 (51.7%) (Table). Bivalirudin was initiated by continuous intravenous infusion (range 0.03–0.2 mg/kg/h) and adjusted to an aPTT of 1.5–2.5 times patient baseline. The mean infusion rate was 0.1 mg/kg/h. The average duration of therapy was 7.8 (range 1–24) days. 7/42 (16.7%) of patients had overt bleeding and received ≥ 2 units of packed red blood cells during their hospitalization. There were three new thrombotic events: ischemic stroke (subtherapeutic aPTT), cephalic vein thrombosis, and left ventricular thrombus. There were no amputations and 5 patients died: 2 withdrawal of care, 1 MSOF, 1 respiratory failure, 1 disseminated intravascular coagulation.
Conclusions: Our experience indicates that bivalirudin is a suitable alternative anticoagulant for patients with HIT or suspected HIT. The bleeding and thrombotic complications were deemed acceptable in our largely critically ill and postoperative patients.
Class of patients No. of pts Indication for initial use of anticoagulation Mean platelet count (K/μL) at the time of bivalirudin initiation (Range) Renal dysfunction (RD) OR Liver dysfunction (LD) OR Both (RD&LD) ICU stay OR Required mechanical ventilation (MV) Multi-system organ failure (MSOF) OR Sepsis VTE = Venous Thromboembolism, Mech Valve = Mechanical Valve, ACS = Acute Coronary Syndrome, Afib = Atrial Fibrillation History of HIT 13 VTE 3, Intervention or Surgery 9, Other 1 172 (30–374) RD 23.1%, LD 0%, RD&LD 0% ICU 61.5%, MV 0% MSOF 7.7% Sepsis 0% Clinically suspected HIT 14 VTE 8, Mech Valve 1, ACS 4, Other 1 57.9 (7–115) RD 21.4%, LD 7.1%, RD&LD 7.1% ICU 85.7%, MV 42.9% MSOF 14.3% Sepsis 28.6% Confirmed HIT 15 VTE 3, Afib 2, ACS 4, Other 6 44.6 (10–107) RD 26.7%, LD 6.7%, RD&LD 13.3% ICU 86.7%, MV 53.3% MSOF 20% Sepsis 20%