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Anticoagulant Managements of Left Ventricular Assist Device Implantation in Two Patients with Heparin-Induced Thrombocytopenia (HIT): Use of Argatroban as an Anticoagulant for Cardiopulmonary Bypass

Kazutomo Saito, Hiroaki Toyama, Yutaka Ejima, Kenji Kurotaki, Masanori Yamauchi and Shin Kurosawa

Heparin-induced thrombocytopenia (HIT) can cause fatal arterial or venous thrombosis/thromboembolism. In high-risk cases, heparin should be immediately discontinued and an alternative administered; the only alternative permitted in Japan is argatroban, a direct thrombin inhibitor. Anticoagulation in patients with recent HIT requiring cardiopulmonary bypass (CPB) surgery is challenging, because it is sometimes difficult to find out appropriate dosage of argatroban using ACT based monitoring calculation.

Two dilated cardiomyopathy patients with HIT were administered argatroban as the anticoagulant for the CPB in left ventricular assist device (LVAD) implantation. After discontinuing argatroban, blood coagulopathy persisted beyond its expected half-life, leading to abnormal haemostasis. Because of severe intraoperative and postoperative bleeding, both patients required massive transfusion support, despite the case 2 performed plasmapheresis to eliminate argatroban at the weaning from CPB. However, blood loss in case 2 (18,159 ml) was significantly lower than that in case 1 (31,292 ml), which might be contributed by the smaller dosage of argatroban (242 mg in case 2 vs. 489 mg in case 1) and plasmapheresis.

Prolongation of ACT is multifactorial and affected by platelet count, fibrinogen concentration and, particularly total dose of argatroban. Furthermore, literatures and our experienses revealed that the recovery time to baseline ACT after stopping argatroban was significantly correlated with the total dose of argatroban (r=0.927). But, we could not authenticate the potency of plasmapheresis to eliminate argatroban and HIT antibodies.

Because no specific antidotes are available for argatroban, surgical teams should carefully monitor timing of argatroban administration and the total dosage.