Which anticoagulant can be used as an alternative to heparin in patients with heparin-induced thrombocytopenia?

• A. Bivalirudin
• B. Warfarin
• C. Enoxaparin
• D. Abciximab

Answer: (A)

In HIT you can’t use heparin or low‑molecular‑weight heparin because the immune reaction to the PF4–heparin complex drives platelet activation and thrombosis. The treatment goal is to anticoagulate without relying on heparin, using agents that do not cross-react with HIT antibodies. Direct thrombin inhibitors fit this role, since they block thrombin directly and don’t involve heparin in their mechanism. Bivalirudin is a direct thrombin inhibitor given by IV infusion with a relatively short half‑life, allowing quick control and easy adjustment based on the patient’s partial thromboplastin time. It’s commonly used in HIT, including during procedures like PCI, when ongoing anticoagulation is needed without heparin.

Warfarin isn’t used right away in HIT because starting it early can precipitate a transient hypercoagulable state due to depletion of protein C, and it’s not effective for immediate anticoagulation in the acute HIT setting. Enoxaparin, while an anticoagulant, is a heparin‑derived factor and can cross‑react with HIT antibodies, increasing thrombotic risk. Abciximab is an antiplatelet agent, not an anticoagulant, and doesn’t address the anticoagulation needs in HIT.