New evidence suggests patients with a history of skin allergy to nickel or other metal components found in coronary stents -- small tubes inserted into narrowed or weakened arteries to help improve blood flow to the heart -- may not need to worry about adverse allergic effects when it comes to stent placement. "Most interventional cardiologists will, at some stage, have to decide whether to place a coronary stent in a patient with a history of skin allergy to one of the metal components, most commonly nickel,” Rajiv Gulati, an interventional cardiologist at Mayo Clinic, said. “Our study found no evidence of an 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.” According to Gulati, there is not much data to support the warnings currently on the product labeling for stents about metal allergies, but caution is still advised.