Animal-Tissue Heart Valves Appear Safe

They equal mechanical devices in extending young patients' survival, study finds.

By Amanda Gardner
HealthDay Reporter
Thursday, November 16, 2006; 12:00 AM

Copyright © 2006 ScoutNews, LLC. All rights reserved.

THURSDAY, Nov. 16 (HealthDay News) -- Young patients who receive replacement heart valves made from animal tissue live just as long as those who get mechanical valves, new research shows.

The results, being presented at the annual meeting of the American Heart Association, in Chicago, stand in contrast to the conventional wisdom but are in sync with current practice, experts say.

"The study confirms the value of putting in tissue valves, even in younger people," said Dr. Robert Bonow, chief of cardiology and professor of medicine at Northwestern University in Chicago, and past president of the AHA.

Heart-valve replacement is one of the oldest types of heart surgery, with two basic types of valves available: mechanical (from manmade materials) or biological (made from animal tissue).

Mechanical devices have long been considered a better option for younger people. The problem is that the risk of blood clots is higher, necessitating the use of anticoagulants (blood thinners) and frequent blood tests.

"There's a trade-off," Bonow explained. "If you put in a mechanical device, you need anticoagulants for the rest of your life, but tissue valves run the risk of degeneration and don't last as long."

Guidelines released in 1998 were "very black and white," Bonow said. "People under 65 were supposed to receive mechanical valves." But, he added, since that time, "the field has moved away from that."

Still, there's been little data to validate whether that move is the best option for younger patients, the team asserted.

"Our goal was to look at very long-term survival implications for patients receiving tissue and mechanical heart valves," said study author Dr. Vincent Chan, a cardiac surgery resident at the University of Ottawa Heart Institute in Canada.

His team analyzed 20-year follow-up data for more than 1,500 patients who had received a new aortic valve or a new mitral valve during the past 35 years. Almost 300 of the patients were under the age of 50 at the time of their first valve operation.