MONDAY, Jan. 26, 2004 (HealthDayNews) -- The sudden death of a heart patient who had a violent immune reaction against a stent has experts puzzled.
Stents, flexible metal tubes, are commonly implanted in arteries after angioplasty, a procedure done to remove blocks created by fatty deposits. The violence of the immune reaction and the fact that it took place 18 months after the stent was implanted are hard to explain, says Dr. Andrew Farb, a cardiovascular pathologist at the Armed Forces Institute of Pathology and a member of the team that reports the incident in the Jan. 27 issue of Circulation.
The stent was a newer kind that is coated with a clot-preventing chemical, but the immune attack appears to have been aimed at the metal in the stent, Farber says.
An immune reaction is not uncommon immediately after a stent implant, but it usually is mild and fades away quickly, he says. In this case, it happened a year and a half after the implant.
"It really is the time frame that makes this case so special," Farb says. "It not only occurred so late, but the pathology was so overwhelming."
Thus far, the case seems to be unique, Farb says. But the incident is enough to prompt a recommendation for cardiologists to be on the alert for the kind of abnormal widening of the arteries that preceded the death of the patient, the journal report says.
The patient was a 58-year-old man who had the stent implanted in Italy early in 2002. After some early, mild problems, he appeared normal, but he suffered chest pain and fainting spells 18 months later. He died of cardiac arrest a few weeks later.
The U.S. Food and Drug Administration was informed at once of the event, says Dr. Dennis Donohoe, vice president for clinical and regulatory affairs for Cordis Corp., a division of the Johnson & Johnson pharmaceutical company, which markets the coated stent.
"Our review indicates that this is a single case," Donohoe says. "We're not aware of any other such deaths related to an allergic response."
The reason for believing the metal in the stent, which contains a large amount of nickel, was the target of the immune attack is that the drug coating mostly had been absorbed when the reaction occurred, he says.
"There definitely is a known background of nickel sensitivity, which occurs in up to 10 percent of the population," Donohoe says. Studies indicate the rate of mild immune reaction is the same for coated and uncoated stents, he says.
Coated stents, which were first marketed by Cordis and now are available from other companies as well, are highly successful in preventing arteries from becoming blocked after angioplasty, Donohoe says.
In the studies that led to FDA approval of the Cordis stent, coated stents reduced the rate of closure by 90 percent, from a 35.4 percent rate for uncoated stents to 3.4 percent for the coated kind, he says.
More information
Learn more about stents and angioplasty from the American Heart Association or HeartCenterOnline.
