What determines the target INR for patients with mechanical heart valves on warfarin?

The target International Normalized Ratio (INR) for patients with mechanical heart valves on warfarin is primarily determined by the type and location of the valve. Different types of mechanical valves (such as bileaflet, ball-and-cage, and others) and their positioning within the heart influence the risk of thromboembolic events.

For example, bileaflet valves typically necessitate a lower target INR compared to older valve designs, which might require a higher target to prevent thrombosis. Additionally, certain locations of the valve, like mitral versus aortic positions, may also reflect different guidelines for INR management due to varying risks associated with each position.

The other options do not directly set the target INR. While the patient's age, duration of treatment, and type of anticoagulant can influence overall management and individual patient considerations, they do not specifically dictate the INR target level for mechanical heart valve patients on warfarin, which is primarily a reflection of the valve characteristics and associated risk factors.