Background: In critically ill patients, heparin-induced
thrombocytopenia (HIT) is estimated to account for
approximately 1 to 10% of all causes of thrombocytopenia. HIT exerts a strong procoagulant state. In case of suspected HIT, it is an important clinical decision to stop heparin and start treatment with alternative nonheparin anticoagulation, awaiting the results of laboratory testing for the final diagnosis of HIT (bridging therapy). Fondaparinux acts by factor Xa inhibition and expresses no cross-reactivity with HIT antibodies. Excretion of fondaparinux is mainly renal. We describe our early experience with fixed low-dose fondaparinux bridging therapy and monitoring of anticoagulant activity for safety reasons.
Methods: This retrospective cohort study was conducted
in a closed format general intensive care unit in a teaching hospital. Consecutive critically ill patients suspected of HIT were treated with fondaparinux after discontinuation of unfractionated heparin or nadroparin. Anti-Xa levels were determined afterwards.
Results: Seven patients were treated with fondaparinux
2.5 mg/day for 1.8 to 6.5 days. Anti-Xa levels varied
from 0.1 to 0.6 u/ml. A negative correlation was found
between creatinine clearance and mean and maximum
anti-Xa levels. No thromboembolic complications
occurred. Bleeding complications were only minor during
fondaparinux treatment. Transfusion requirements did
not differ significantly between treatment episodes with
fondaparinux or with heparin anticoagulants.
Conclusion: In this small sample of critically ill patients
suspected of HIT, bridging therapy with fixed low-dose
fondaparinux resulted in prophylactic and therapeutic anti-Xa levels. Monitoring of anticoagulant activity is advised in patients with renal insufficiency.