A heart valve manufacturer bowed to the demands of consumer activists and agreed to inform thousands of implant patients of potential defects. Shiley Inc. of Irvine, a subsidiary of New York-based Pfizer Inc., said Tuesday it will identify and notify 21,000 patients in the United States of product defects that could prove dangerous. Its notices will advise patients about the warning signs of mechanical valve failure and what steps to take should the device fail, company officials said. The announcement affects those patients who received the Bjork-Shiley 60-degree ``convexo-concave'' heart valve. The company voluntarily pulled the valves from the U.S. market in 1986 following reports of valve fractures. Roger Sachs, vice president and medical director at Shiley, said the firm was determining how patients will be notified. He said Shiley was negotiating with another company to compile a registry of implant patients. The decision comes after Public Citizen Health Research Group, a Washington, D.C.-based consumer organization, filed a lawsuit against Shiley and Pfizer to force Shiley to warn patients about the defects. A judge dismissed the suit in May after ruling that the U.S. Food and Drug Administration had sole authority to issue such an order. ``If the company does what it says it is going to do, there is no question that some people who otherwise would die will live,'' said Public Citizen's director, Dr. Sidney Wolfe. ``I think they (Shiley) saw the handwriting on the wall and yielded to something they should have done a long time ago,'' he added. Originally, Shiley had cautioned only surgeons about the valve's problems, replying upon them to notify their patients. In March, the company mailed warnings to surgeons, cardiologists, primary physicians and emergency room practitioners. A statement issued Tuesday by Shiley said the decision to notify patients directly came in response to FDA concerns that physicians may not have effectively communicated the product's defects to implant patients. Shiley officials added they will ask the FDA to review the notices it will send to patients. FDA spokeswoman Susan Cruzan said the agency could decide by early next year whether to require valve manufacturers to notify patients directly of any potential product defects.