Fondaparinux in Patients With Acute Heparin-Induced Thrombocytopenia (HIT)

Inclusion Criteria: * Male or female at least 18 years of age; * If female of childbearing potential, negative pregnancy test result; * Diagnosis of HIT confirmed by the following: Decreased platelet count by 50% or greater OR platelets \< 100,000/mm3 during or within 2 weeks after heparin exposure and/or new thromboembolic complications during or within 2 weeks after heparin exposure; * Laboratory confirmation (either heparin PF4 antibody or serotonin release assay positive). Exclusion Criteria: * Estimated creatinine clearance less than 30 ml/min (either measured or by using Cockcroft Gault equation); * Pregnancy or lactating; * Blood dyscrasia other than HIT; * History of thrombocytopenia associated with fondaparinux; * Recent (within 6 weeks) or planned surgery of CNS, eye or traumatic surgery resulting in large open surfaces or other procedures with high bleeding risk or if lumbar puncture is planned; * Active bleeding of GI tract, GU tract, CNS or respiratory tract; * Malignant hypertension, pericarditis, pericardial effusion, endocarditis or eclampsia; * Inadequate laboratory facilities, inadequate support system at home, alcoholism, drug abuse, psychosis or dementia; * Hypersensitivity or contraindication to warfarin or fondaparinux.