slow recruitment

Heparin is an anticoagulant (blood thinner) that is commonly used to treat patients with heart attacks and patients with blood clots in their legs or lungs (venous thrombosis). Some patients develop an allergic reaction to heparin, a condition called heparin-induced thrombocytopenia (HIT). HIT makes blood clot, which is the opposite of what heparin was designed to do. These blood clots can lead to heart attacks, strokes, limb amputations, and death. The objective of this 200 patient study is to determine if a new blood thinner called rivaroxaban (Xarelto) can be used to treat HIT. Rivaroxaban can be taken by mouth, does not require blood testing, and had a low risk of bleeding when it was used to treat blood clots in other clinical trials. If this study shows that rivaroxaban can be used to treat HIT, there will be two very important benefits. For patients with HIT, the benefit will be having a safe, and easy-to-use drug to protect them from developing further life or limb-threatening blood clots. For the Canadian health care system, the benefit will be having a drug that is much less expensive than the drugs currently used to treat HIT.

Consecutive adult patients with an intermediate or high clinical probability for HIT (according to the clinical prediction rule called the "4T's Score) will receive rivaroxaban 15 mg bid while awaiting confirmation or exclusion of HIT by the local laboratory assay. Patients who are confirmed to have HIT by the local laboratory assay will continue to receive rivaroxaban 15 mg bid until their platelet count ≥ 150 or until end of study (Day 30). At the time of platelet count recovery (typically 4-7 days), they will be transitioned to a maintenance dose of rivaroxaban (20 mg od) for a maximum of 30 days.

Inclusion Criteria:

• Adult patients with 4T's Score greater than or equal to 4.

Exclusion Criteria:

• Require ongoing anticoagulant therapy for a mechanical heart valve.
• Severe renal insufficiency (CrCl<30 ml/min)
• Hepatic disease (including Child-Pugh B and C) associated with coagulopathy and a clinically relevant bleeding risk
• Inability to take oral medications.
• Ongoing requirement for systemic treatment with azole-antimycotics (except fluconazole) or HIV-protease inhibitors or strong CYP3A4 inducers
• Clinically significant active bleeding or lesions at increased risk for bleeding within the last 6 months
• Platelet count less than 80 and an ongoing need for antiplatelet therapy may be excluded at the discretion of the investigator
• Pregnant or a woman of child-bearing potential not using an adequate birth control method
• Hypersensitivity to rivaroxaban or to any ingredient in the formulation.