For AVR, Which Valve Is Best?

Tissue-based heart valves may benefit middle-aged patients undergoing aortic valve replacement more than metal-based valves

(RxWiki News) Tissue or metal? For aortic valve replacement (AVR) surgery, which one you choose may make a difference.

A new study from Australia found that middle-aged patients who underwent AVR fared significantly better with tissue-based replacement valves than with metal-based ones.

Patients in this study who received metal valves were about twice as likely as patients who received tissue valves to experience a major bleeding event or blood clot within 15 years of surgery.

"We combined the best available evidence comparing [metal] valves versus [tissue] valves to determine the risks and benefits to patients following surgery, depending on the type of valve they received," said lead study author James J. Wu, a cardiothoracic surgeon at the University of Sydney, in a press release. "We hope that our results can give future patients needing AVR more information to help them choose the appropriate replacement valve for their condition."

AVR is a type of surgery used to treat patients with aortic valve disease. During this surgery, a damaged aortic valve is removed and replaced with an artificial one. Some artificial valves are composed of man-made substances like metal. Others are composed of animal tissue, often taken from a pig.

The main advantage of metal valves is their durability — they don't wear out as fast as tissue ones. However, blood tends to clot on metal, which can increase the risk of stroke. That means patients who receive these valves must take blood-thinning medications for the rest of their lives.

Tissue valves are less likely to cause blood clots, but may need to be replaced in the future.

For this study, Wu and team looked at 13 prior studies on middle-aged patients (ages 40 to 70) undergoing AVR.

At 15 years post-surgery, tissue valve patients were about twice as likely as metal valve patients to need another surgery to replace a worn-out valve. However, metal valve patients were about twice as likely to experience a major bleeding event or blood clot.

Because these events are linked to a significantly higher risk of death than additional surgery, researchers concluded that tissue valves should be strongly considered for patients in this age group.

No differences in the rates of survival, stroke or endocarditis (infection of the heart lining) between either valve type were found.

This study was published online Jan. 12 in the journal The Annals of Thoracic Surgery. No funding sources or conflicts of interest were disclosed.

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Review Date: 
January 11, 2016