Mechanical or biological heart valve:
what are the differences?

Article written and reviewed by Dr Luca Moretti

When a heart valve has to be replaced, there is no single prosthesis that is best for everyone. A mechanical valve is very durable but requires permanent anticoagulation with a vitamin K antagonist. A biological valve does not require lifelong anticoagulation solely because the prosthesis is present, but it can deteriorate over time and make another intervention necessary.
The choice is therefore a balance between prosthesis durability, bleeding risk, the likelihood of needing another intervention and the person’s preferences.

The 2025 ESC/EACTS guidelines emphasize that the decision should be shared with the patient. Age is important, but it is not an automatic rule: life expectancy, other diseases, the ability to maintain good INR control, daily activities, any plans for pregnancy and the options available if the prosthesis later deteriorates all matter.

What is the difference between a mechanical and a biological valve?

Mechanical prostheses are made of highly durable artificial materials. Their main advantage is durability: structural deterioration is rare. The disadvantage is that blood is more likely to form clots on the prosthesis, so lifelong treatment with a vitamin K antagonist anticoagulant and regular monitoring of the INR are necessary.
The INR target is not the same for everyone: it depends on the type and position of the prosthesis and on any factors that increase thrombotic risk.

Biological prostheses are made of treated tissue, generally of animal origin, mounted on a supporting frame or used in transcatheter systems. They have a lower tendency to thrombosis than mechanical valves and do not require permanent anticoagulation solely because they are present.
The limitation is structural valve deterioration: over the years, the leaflets can calcify, stiffen or become damaged, causing stenosis or regurgitation. This process tends to occur earlier in younger patients.

How long they last and what happens if a biological prosthesis deteriorates

There is no single number of years that applies to every bioprosthesis. Durability depends on the model, position, age at implantation and individual characteristics. In general, the younger the patient, the greater the risk that a biological prosthesis will deteriorate during that person’s lifetime.
For this reason, the initial choice must consider not only today’s procedure but also the so-called lifetime strategy: what will technically be possible if that prosthesis fails many years later.

A degenerated bioprosthesis does not automatically mean another open-heart operation. In some patients, a new transcatheter valve can be implanted inside the previous one in a valve-in-valve procedure. This solution, however, is not possible or optimal for every anatomy: prosthesis size, the risk of obstructing the coronary arteries and the risk of leaving high gradients must be assessed in advance.

The possible causes of problems after valve replacement are not all the same as prosthesis aging. Structural valve deterioration must be distinguished, for example, from thrombosis, endocarditis and non-structural abnormalities.

How age affects the choice

Age serves as a practical indicator of life expectancy and therefore of how long the prosthesis will need to function. According to the 2025 ESC/EACTS guidelines, a mechanical valve should be considered especially below 60 years of age in the aortic position and below 65 years in the mitral position, if there are no contraindications to anticoagulation.
A biological prosthesis should instead be considered especially above 65 years in the aortic position and above 70 years in the mitral position.

These thresholds are not rigid boundaries. Between the indicated ages there is a range in which both options may be reasonable. Even outside those ranges, a person may have important reasons for preferring the apparently less typical option.
A younger person with high bleeding risk or an inability to monitor the INR regularly may be directed toward a bioprosthesis; a person with a long life expectancy and a strong desire to avoid reinterventions may instead prefer a mechanical prosthesis.

Anticoagulants, INR and daily life

With a mechanical prosthesis, anticoagulation with a vitamin K antagonist is permanent. Direct oral anticoagulants such as apixaban, rivaroxaban, edoxaban or dabigatran must not be used instead of vitamin K antagonists to prevent thrombosis of a mechanical valve.
Treatment requires INR monitoring, attention to interactions with other medications and planned management when operations or invasive procedures are needed.

A biological prosthesis does not necessarily mean that anticoagulants are absent. After implantation, antithrombotic medications may be prescribed according to the type of prosthesis and procedure performed; moreover, a person may have another indication for anticoagulation, such as atrial fibrillation.
It is therefore not correct to choose a bioprosthesis simply on the assumption that it means “no anticoagulants.”

Pregnancy, sports and other situations that can influence the decision

A future pregnancy weighs heavily in the choice. Mechanical prostheses require anticoagulation that is essential to protect the mother from valve thrombosis, but the different medications that can be used during pregnancy involve different risks and trade-offs for the mother and fetus. The 2025 guidelines therefore favor a biological prosthesis, when appropriate, in women who anticipate a pregnancy.
If a mechanical prosthesis is already present, pregnancy must not be managed by changing treatment independently: it requires specialist planning and a Pregnancy Heart Team.

Work or sports activities with a high risk of trauma may also make permanent anticoagulation less desirable. Conversely, already needing a vitamin K antagonist for another indication may reduce one of the practical disadvantages of a mechanical prosthesis.
The final choice should therefore be made after discussing not only the durability of the two valves, but also how each option would concretely affect the person’s life.

Frequently asked questions about choosing a prosthesis

Which lasts longer?
The mechanical valve. Bioprostheses can degenerate over time, especially when implanted in younger people.

Do you need to take anticoagulants for life with a mechanical valve?
Yes. Permanent anticoagulation with a vitamin K antagonist is necessary, with an INR target defined according to the prosthesis and risk profile.

Does a biological valve always avoid anticoagulants?
No. Antithrombotic therapy may be needed after the procedure or anticoagulation may be required for other cardiac conditions.

Does age alone determine the choice?
No. Age thresholds guide the choice but do not replace individual assessment and the patient’s informed preferences.

If I want a pregnancy, which prosthesis is preferred?
When appropriate, guidelines favor a biological prosthesis because it avoids the complex mandatory anticoagulation associated with mechanical valves.