Which anticoagulation strategy is used for antithrombin deficiency?

• A. Warfarin alone
• B. DOAC monotherapy
• C. Heparin then aspirin
• D. LMWH → warfarin or DOAC ± antithrombin concentrate supplement

Answer: (D)

In antithrombin deficiency, heparin-based anticoagulation can be ineffective because heparin requires antithrombin to inhibit thrombin and factor Xa. The key is to restore antithrombin activity so heparin/LMWH can work, then switch to a long-term option that doesn't rely on antithrombin. Start with low-molecular-weight heparin and, if needed, give antithrombin concentrate to replenish levels. Once the patient is stabilized, transition to long-term anticoagulation with either warfarin or a direct oral anticoagulant (DOAC). In some cases, continuing antithrombin concentrate alongside anticoagulation is considered if ongoing AT deficiency would blunt heparin-based therapy. This approach addresses both the acute need for effective anticoagulation (via LMWH with AT) and the long-term prevention (via warfarin or DOAC). Warfarin alone would lack immediate protection and DOAC monotherapy is typically used after initial heparin-based management; aspirin is antiplatelet rather than anticoagulant and is not the primary strategy here.