Mechanical heart valves may be safer than biological ones: study

In certain cases mechanical heart valves may be safer than those made of animal tissue and should be used more as a replacement, especially in younger patients, a study says.

According to researchers at the Stanford University School of Medicine in the US, the best choice could depend on whether the aortic or mitral valve is being replaced.

The study showed that for patients undergoing mitral valve replacement, a mechanical valve is actually beneficial until the age of 70, while for patients undergoing aortic valve replacement, the benefit of implanting mechanical valves ceased after the age of 55.

"This has potential to significantly impact the current national practice guidelines," said Joseph Woo, professor at Stanford, PTI reported.

Most patients in need of open-heart surgery to remove a diseased heart valve have to take a call after consulting with their heart surgeons about whether to use a natural-tissue or mechanical valve as a replacement.

Mechanical valves can last a lifetime, but they come with increased risks of blood clotting and bleeding and patients necessitate lifetime use of blood-thinning medication warfarin.

On the other hand biological valves, mostly made from pig or cow tissue, do not increase the risk of bleeding or clotting, but wear out within about 10 to 15 years, making a second surgery likely.

What makes the decision difficult is the lack of sufficient scientific evidence to back up either choice, according to Woo.

For people younger than 50, a mechanical valve is currently recommended, and for those older than 70, a biologic tissue valve is recommended, Woo said.

However, the guidelines do not make a distinction between whether the mitral or aortic valve is being replaced.

"If you think about this just in terms of age, the older you are, the less likely that you will outlive the durability of a biological valve," Woo said.