SYDNEY, Jan. 12 (UPI) -- Middle-aged patients who have aortic valve replacement, or AVR, may do better after surgery with tissue-based valves rather than metal ones, according to a new study.
Researchers at the University of Sydney report that while metallic valves tend to last longer, they can cause health issues not associated with bioprosthetic valves, such as blood clots forming on the valve.
Metal valves usually require patients to take blood thinning medications to prevent clots, which can break off and clog the valve, if not form an embolism, and move into the bloodstream and clog another blood vessel, leading to heart attack or stroke.
Bioprosthetic valves, often created from animal donors, can last 10 to 20 years, according to the American Heart Association, and don't require long-term medication, however the chances are high patients will need another surgery or valve replacement later in life.
"This is a complex decision that requires up-to-date evidence," said Dr. Paul Bannon, a researcher at the University of Sydney, in a press release. "There are options to reduce the bleeding risk of mechanical valves, so, ideally, a discussion with both the surgeon and cardiologist is warranted to take into account an individual's circumstances."
For the study, published in Annals of Thoracic Surgery, researchers analyzed 13 studies comparing the two types of valves used in replacement surgeries for patients between the ages of 40 and 70.
Fifteen years after the procedure, no significant difference was found for survival, freedom from stroke, or freedom from infection of the inner lining of the heart or the valves. Mechanical valves were associated with a significantly lower risk of reoperation, but were linked to more thromboembolic and major bleeding events compared to bioprosthetic valves.
While researchers say the study supports the use of bioprosthetic valves in patients younger than than 65 years old, the current recommendation for doctors, they caution the risks and benefits should be evaluated based on the health situations and age of individual patients.
"We combined the best available evidence comparing mechanical valves versus bioprosthetic valves to determine the risks and benefits to patients following surgery, depending on the type of valve they received," said James Wu, a researcher at the University of Sydney. "We hope that our results can give future patients needing AVR more information to help them choose the appropriate replacement valve for their condition."