Comparison of bivalirudin to lepirudin and argatroban in patients with heparin-induced thrombocytopenia

OBJECTIVE: To evaluate the safety, effectiveness, and dosing of off-label bivalirudin to argatroban and lepirudin in patients with heparin-induced thrombocytopenia (HIT) using a new pharmacist driven protocol. METHODS: Retrospective cohort study of forty eight patients treated with lepirudin, argatroban, or bivalirudin from November 2010 to February 2012 for suspected HIT. Patients were excluded if the bivalirudin therapy was being used for acute coronary syndrome or if the treatment duration was less than 24 hours. The primary endpoint was time to therapeutic activated partial thromboplastin time (aPTT 50-90 seconds for argatroban and bivalirudin and 50-85 seconds for lepirudin). The secondary endpoints were elevation in international normalized ratio (INR), bleeding episodes, and percent time in aPTT target range. RESULTS: Patients receiving bivalirudin reached a therapeutic aPTT more quickly than those receiving argatroban and lepirudin (3.7 hours vs. 14.2 hours vs. 14.7 hours, p <0.001). The INR was increased more in patients treated with argatroban than lepirudin and bivalirudin (1.3 vs. 0.3 vs. 0.4, p = 0.4). Clinically significant bleeding in patients treated with bivalirudin was significantly lower than that observed with argatroban or lepirudin (7% vs. 22% vs. 56%, p = 0.02). The average percentage of therapeutic aPTTs drawn was higher for patients treated with bivalirudin than those patients treated with argatroban and lepirudin (90% vs. 66% vs. 67%, p = 0.2). CONCLUSION: A pharmacist-driven protocol for bivalirudin provided a significantly shorter time to therapeutic aPTT and lower bleeding rate for patients being treated for HIT when compared to lepirudin and argatroban. A larger study should be considered to confirm the results of this single center study.