Risk of fracture for some sizes of these valves may be higher. The Food and Drug Administration has asked Shiley Inc. of Irvine, Calif., the maker of Bjork-Shiley heart valves, to notify patients and physicians that risk of fracture for some sizes of these valves may be higher than previously thought.
The fracture rate for the large sizes of the 60-degree Shiley (C-C) valve is now thought to be as much as five times higher than previously estimated. Valve fracture is often fatal. FDA believes that the risk of fracture of these large valves, over an eight-year period, when implanted to substitute for the heart’s mitral valve, may be high enough for doctors and patients to consider replacing currently intact valves in some individuals.
“When a critical device such as a heart valve is found to have a problem that could result in death or serious injury, FDA has an obligation to see that doctors and patients are notified so that they can consider the new
information in deciding on a course of action,” said FDA Commissioner David A. Kessler, M.D.
About 23,000 people in the United States and Canada have 60-degree Shiley (C-C) valves
About 23,000 people in the United States and Canada have 60-degree Shiley (C-C) valves. These valves were removed from the market in 1986.
FDA has received about 350 reports of 60-degree valve fractures among the roughly 82,000 C-C valves implanted worldwide.
FDA requested Shiley to notify patients with these valves of the fracture problems, in a program begun in 1990 after the agency became aware of some risk of fracture.
However, replacement of intact valves was not
recommended at that time because the surgical risk was thought to far outweigh the risk of fracture.
The risk of fracture depends on the age of the patient, valve size and valve position. The rate may be as high as 0.8 percent per year for people under 50.
Which patients should now have their heart valve replaced is a decision that should be made on a case by case basis by physicians, based on the new fracture figures and the patient’s medical status, lifestyle and wishes.
Since certain patients may be at higher risk for valve fracture than was previously known, it is important for patients with the larger valves, especially those in the higher risk group–younger patients with the larger
valves implanted in the mitral position–to talk to their doctors about what the new risk numbers mean to them, Dr. Kessler said.
FDA asked Shiley to send letters to all patients with C-C heart valves
FDA asked Shiley to send letters to all patients with C-C heart valves informing them of the increased risk of fracture. Patients in the affected groups will be provided with both the new and old fracture risk figures for
various valve sizes and age groups and will be advised to discuss the new information with their doctors.
Patients unaffected by the new figures will be reassured that the new data do not apply to them.
Shiley was also asked to send a letter to physicians, enclosing a copy of the study upon which the higher estimates are based and discussing the option of valve replacement.
“It is important to remember that this new risk information applies only to Shiley C-C valves, not to other makes and models,” said James S. Benson, director of FDA’s Center for Devices and Radiological Health.
“Even with the C-C valves, the increased fracture risk is confined to certain size valves. The risk figures have not appreciably changed for C-C valve patients who have the smaller size valves.”
The study on which the new estimates of risk are based was published in the Feb. 1 British medical journal The Lancet.