What is the therapeutic INR range after mechanical valve replacement?

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After mechanical valve replacement, lifelong anticoagulation with warfarin is needed because the artificial valve is prone to forming clots. The INR is used to gauge how thin the blood is and to keep it high enough to prevent valve thrombosis but not so high that bleeding occurs. For most mechanical valves, the therapeutic range sits above normal but not overly high. Among the given ranges, 2 to 3 best fits this balance: it’s high enough to lower clot risk compared with a normal population, yet not so high as to unduly raise the bleeding risk. In reality, some situations (like a mitral mechanical valve) may require higher targets (around 3 to 4), but the commonly tested range that fits the options is 2–3. Subtherapeutic levels (1–2) increase clot risk, while higher ranges (3–4 or 4–5) raise bleeding risk and are used selectively based on valve position and patient factors.