Allergy in coronary in-stent restenosis

Abstract

Sir—Ralf Koster and colleagues (Dec 2, p 1895) report on nickel and molybdenum contact allergies in patients with coronary restenosis. We have reservations about their study design and the interpretation of their findings. 131 patients presented with suspected restenosis after coronaryartery stenting underwent patch testing for possible metal allergy. Ten (8%) patients had a delayed-type hypersensitivity reaction to nickel (seven) or molybdenum (four), one reacting to both. All had stent restenosis of more than 50%. However, the prevalence of nickel allergy in the general population is around 10% in women and 1–2% in men, and, therefore, the high incidence in the study population is not altogether unexpected. The finding of molybdenum allergy is surprising since this element is not recognised as a contact sensitiser. As such, molybdenum is not regularly used in patch testing and so there is little guidance on the concentration of salt to apply. Metal chlorides can be irritant even in low concentration and, although Koster and colleagues used a low concentration of salt, this finding needs to be verified with use of more controls. Paediatric emergency care in less-developed countries