Coronary stent restenosis and the association with allergy to metal content of 316L stainless steel

BACKGROUND: Most intra-coronary stents in use are made of 316 L stainless steel, which contains nickel, chromate and molybdenum. Whether inflammatory and allergic reactions to metals contribute to in-stent restenosis is still a matter of debate. AIM: The aim of this study was to ascertain the relationship between metal allergy and the occurrence of in-stent restenosis. METHODS: Ninety-nine adult patients who underwent two cardiac catheterisations, up to two years apart, were included in the study. Seventy patients had patent stents at the second angiogram (patent stent group) and 29 were found to have in-stent restenosis (restenosis group). All patients underwent patch testing with the relevant metals and the 316L stainless steel plate. RESULTS: Twenty-eight (28.3%) patients were found to have an allergy to at least one metal. There was no significant difference in the prevalence of metal allergy between the patent stent group and the restenosis group (28.6 and 27.6%, respectively; p = 0.921). CONCLUSION: Our data do not support the theory that contact allergy plays a role in the pathogenesis of in-stent restenosis.