Fondaparinux for the treatment of patients with acute heparin-induced thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a life-threatening immune response to heparin that is associated with a high risk of thromboembolic complications. We prospectively treated seven subjects with acute HIT with fondaparinux and compared the results to a similar historical control population from the same hospital. Six of the seven fondaparinux-treated subjects were transitioned to warfarin, beginning after platelet count recovery occurred. Ten historical controls were treated with a direct thrombin inhibitor (DTI), eight of which were transitioned to warfarin. The primary study outcome was platelet count recovery which was defined as an increase from baseline by at least 30% of nadir to greater than 100,000/mm(3) by day seven. Seven subjects were prospectively treated with fondaparinux for a median of eight days. Six of the seven had HIT with thrombosis at the time of enrollment. All fondaparinux treated subjects had a complete platelet count recovery, and none experienced a new thromboembolic complication, major bleeding or death by week four. One subject underwent limb amputation. Ten historical controls were treated with a DTI for a median duration of eleven days. Platelet count recovery occurred in eight of the ten historical controls. No new thromboembolic complications or major bleeds occurred but limb gangrene occurred in four controls. The development of limb gangrene in the historical controls may have been a result of delayed recognition of HIT and/or inappropriately early institution of warfarin in the historical controls. This pilot study suggests that fondaparinux may be useful in patients with acute HIT.