A study of coronary patients with sensitivity to metal and who have received metal stents found that those patients did not experience any adverse health risk nor any allergic reaction to these medical devices, report the authors of the research at the Mayo Clinic.
The study is the first to compare clinical reactions in patients who have sensitivity to metal with those without a history of metal skin allergies. Both groups received stents — small tubes places in narrowed or weakened arteries to help improve blood flow to the heart — containing nickel and other metal components. The findings are published in an April issue of Circulation: Cardiovascular Interventions.
Dr. Rajiv Gulati, an interventional cardiologist at the clinic, says:
Our study found no evidence of increased risk of heart attack, death or restenosis, which is a recurrent narrowing within a stent, in patients who reported themselves to be allergic to metal prior to implantation. These findings should provide some reassurance to clinicians and patients who are faced with this clinical issue, especially as there has been scarce and conflicting information in the literature.
Researchers followed early and long-term reactions in 29 patients with a history of metal allergies and compared them with a control group of 250 nonallergic patients. In addition to finding no differences between the two groups in increased health risks, the study also found that white blood cell, eosinophil, and lymphocyte counts did not change after the stents were inserted. The finding lends weight to the idea that there is no worrisome systemic immune reaction to the stents in those with a history of skin allergies, the clinic says.
Coronary stents in the United States have been made since 1997 with stainless steel, cobalt-chromium, or platinum-chromium alloy platforms. All stents contain some nickel (10% to 35%) and chromium as chromate (18% to 20 %).
About 8% of the population has a skin allergy when coming into contact with nickel. “We do not routinely test for nickel allergy, so we don’t know how many people coming to the cath lab have this problem,” Gulati says. “Still, our findings would suggest that the mechanism of skin reaction to metal exposure might differ from that within the arterial wall.”
Labels for stents marketed in the United States must include warnings about potential contraindications in people with metal allergies. There is not much data to support those warnings, Gulati says, but he advises patients to take caution and he recommends that further research take place.
Source: “Mayo Clinic Study Suggests Coronary Stents Not Harmful to Patients with History of Metal Allergy,” Mayo Clinic, 4/16/12
Image by U.S. Food and Drug Administration, used under Fair Use: Reporting.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.