Clinical And Experimental Studies of Contact Allergy to Stent Metals - with focus on gold
Abstract: A large number of patients are treated with coronary stents, and restenosis (recurrent narrowing of the vessel) is a serious problem. Contact allergy to metal ions eluted from stainless steel stents has been suggested to contribute to in-stent restenosis. Studies have reported a higher rate of restenosis with gold-plated stents, but the correlation to contact allergy was not evaluated. Nickel is the most common contact allergen known, with a median prevalence of 8.5% in North America and Western Europe. Contact allergy to gold has been demonstrated by patch testing with various gold salts and with the metal itself. The patients included in the study had received one type of stent manufactured from stainless steel but differing in that one was electroplated with gold. The result of this work show that contact allergy to gold is more common in a stented population than in a control population. Dental gold, ear piercing and age were all found to be independent risk factors for contact allergy to gold. However, the possibility of sensitization due to the gold-plated stent remains. Statistical analysis suggests the induction of contact allergy to gold due to the gold-plated stent implanted in the coronary vessel. Allergy to Myroxylon pereirae (a wood extract used in dental cement, as fragrance in cosmetics, creams, ointments and as flavouring) and caine mix (three anaesthetics for topical use), was also more common in the stented population than in controls, indicating the importance of the oral mucosa for sensitization. A correlation was found between gold-plated stents, contact allergy to gold and an increased frequency of restenosis. The gold concentration in blood (B-Au) was 5 times higher in gold-stented patients than in Ni-stented patients. The patch test reactions for gold were also correlated to B-Au: the higher the B-Au, the stronger the patch test reaction and the lower the concentration eliciting a positive patch test. In conclusion, the results indicate that implantation of a gold-plated stent in the coronary vessel induces gold allergy, and that contact allergy could be a risk factor in the restenosis process. The findings underline the importance of careful evaluation of new products, routines and materials with regard to the risk of sensitization and/or elicit an allergic reaction to a contact allergen. The gold concentration in blood was shown to correlate with the result of patch tests, which indicates that systemic exposure to an allergen, at least in the case of gold, causes skin reactivity to gold following topical exposure.
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