Which device requires warfarin to prevent clot formation on the valve?

• A. Bioprosthetic valve
• B. Mechanical valve
• C. Cardiac pacemaker
• D. Stent

Answer: (B)

Clotting risk is highest on artificial valve surfaces, and the type of valve determines whether long-term anticoagulation is needed. A mechanical valve uses non-biologic material that disrupts blood flow and provides a surface where clots can form, so patients typically require lifelong warfarin to prevent valve-related thrombosis and stroke. Bioprosthetic valves are made from animal tissue and are less prone to clotting, so they often don’t need ongoing warfarin (antiplatelet therapy may be used instead or in combination with other risk factors). A cardiac pacemaker is not a valve and does not inherently require warfarin to prevent clotting on the device. Stents are vascular devices where antiplatelet therapy is standard to prevent in-stent thrombosis, not routine warfarin for the device itself. Therefore, the device that requires warfarin to prevent clot formation on the valve is the mechanical valve.