A small percentage of patients are allergic to the polymer on drug-eluting stents, and a handful have died from the reactions, according to an adverse-event records review initiated by cardiologists from the Health Science Center. The allergy risk to the vast majority of patients is small, the authors note.
“The patients in question are not allergic to the stent itself, but to the polymer coating the metal used to hold the drugs for 30-day release,” said the report’s senior author, Marc D. Feldman, M.D., associate professor of medicine at the Health Science Center and associate director of cardiac catheterization laboratories at its teaching hospital, University Hospital. “We conclude that a next generation of drug-eluting stents is needed to deliver drugs without polymers. This is an important issue of which the public and the medical community should be aware.”
Dr. Feldman located cases himself, and also asked biostatisticians and epidemiologists at Northwestern University and the University of Utah to analyze a U.S. Food and Drug Administration (FDA) database of adverse events since the first drug-eluting stent’s introduction in 2003. The groups identified 17 distinct cases that were probably or certainly caused by two well-known drug-eluting stents. Autopsies of four individuals who died of heart attacks revealed inflammation caused by immune activity against the polymer.
“This is not seen in patients with bare-metal stents,” Dr. Feldman said.
The study will appear in the January issue of the Journal of the American College of Cardiology. The Journal made the article and an accompanying editorial available to physicians by early online publication. Jorge Alvarez, M.D., and Gordana Gligoric, M.D., Ph.D., of the Health Science Center are among the 18 co-authors.
Dr. Feldman, who conceived the study and enlisted the help of the other research groups, is working with Brooke Army Medical Center in San Antonio to develop a skin test for polymer hypersensitivity. “We’d love to evaluate patients who think they have this syndrome,” he said. “All patients referred to the three universities will come to our cardiologists in San Antonio.”
Symptoms from cases reported to the FDA included rash, shortness of breath, hives, itching and fevers. Any physician who suspects a patient may have an allergic reaction to a drug-eluting stent may call (210) 567-2106 to reach Dr. Feldman’s group.
The prevalence of allergic reactions to drug-eluting stents is unknown, but Dr. Feldman said reactions are probably rare. Many untold thousands of physicians treated their patients with drug-eluting stents without incident and did not feel any need to contact the FDA.
The drug-eluting stent hit the market two decades after Julio Palmaz, M.D., of the Health Science Center, invented the first stent in the 1980s. Dr. Palmaz’s stent and succeeding generations of stents have saved countless lives and reduced the need for open-heart surgery. Today, stents are used in 2 million patients annually. The Palmaz Stent, which never had a polymer attached to it, is one of the world’s most successful medical devices, and the original patent has been called one of the 10 most significant medical patents in the world.