Bivalirudin Use With Percutaneous Ventricular Assist Device in Suspected Heparin-Induced Thrombocytopenia

We describe a patient case utilizing a bivalirudin purge solution with an Impella CP device (ABIOMED, Inc, Danvers, MA) in a patient suspected of having heparininduced thrombocytopenia (HIT). An 85-year-old man weighing 104 kg presented with chest pain, hypotension, and ST-segment and J-point depressions, in cardiac shock. Significant cardiac history included coronary artery disease, 2 coronary artery bypass grafts, implanted cardioverter, atrial fibrillation, and heart failure. Labs demonstrated a creatinine clearance of 50 mL/ min and positive troponins. All other available laboratory values at admission were within normal limits (Table 1). The patient experienced cardiac arrest in the catheterization lab and was successfully resuscitated. A stent was placed in the left anterior descending artery. An ECHO demonstrated an ejection fraction of 5% to 10%. An Impella was placed for cardiac support. The patient remained on a ventilator with propofol, norepinephrine, and Impella with heparin-based anticoagulation. He was started on 81 mg aspirin daily and ticagrelor 90 mg twice daily after the loading dose. On day 3, his platelet count dropped from a baseline of 158 to 56 × 10/L leading to a suspicion of HIT. The purge solution and systemic anticoagulation were switched to bivalirudin, and a heparininduced platelet antibody (HIPA) test was collected. The purge solution consisted of 25 mg of bivalirudin in 500 mL of 5% dextrose. Impella infuses the purge solution at a variable rate that averages roughly 0.01 mg/kg/h. Systemic bivalirudin, per recommended HIT dosing (0.15 mg/kg/h) for normal renal function, was initiated at a dose of 0.14 mg/kg/h to account for systemic exposure from the purge solution. The systemic bivalirudin was adjusted to maintain our institution’s therapeutic range of activated partial thromboplastin time (aPTT) of 40 to 60 s (1.5-2.5 times that in controls). Purge and systemic anticoagulation were continued for 23 hours until the HIPA returned negative. The patient was then switched back to heparin. While on bivalirudin, the patient maintained therapeutic aPTTs in 8 of 9 results. No bleeding complications were experienced, and the functionality of the device was maintained while on bivalirudin. On day 5, Impella was removed with no further cardiovascular interventions planned. A platelet infusion was given in preparation and immediately after the device removal. Furosemide was initiated. The patient remained on ventilator and vasopressor support. On days 6 to 7, the patient developed fever with a slight increase in white blood cells, worsening hypotension, and plural effusions from volume overload. The patient’s code status was changed to withdrawal of care, and died late on the seventh day. Impella complications may include platelet destruction, leading to thrombocytopenia from the device itself or HIT from the heparin-based anticoagulation. This presents a challenge because there is limited literature available for anticoagulation in these patients suspected of having HIT. Two similar patient cases utilized argatroban for the purge and systemic anticoagulation; both demonstrated successful maintenance of therapeutic aPTTs and device functionality. Another successfully anticoagulated the patient using only an argatroban-based purge solution without systemic anticoagulation because the patient had liver failure. Unfortunately, argatroban at our institution is purchased as a premixed product suspended in normal saline. Normal saline can corrode and compromise the device according to the manufacturer. 875151 AOPXXX10.1177/1060028019875151Annals of PharmacotherapyRobinson et al research-article2019