Recurrent coronary artery in-stent restenosis caused by metal allergy: a case report

This article describes the case of a middle-aged woman who developed recurrent in-stent restenosis (ISR) due to metal allergy. The first ISR occurred after implantation of a nickel-rich Medtronic Endeavor Resolute stent (35% nickel, 35% cobalt, and 20% chromium). A skin patch test revealed a strong nickel allergy (++), with no allergic reaction to cobalt. Nickel allergy was considered to be the cause of the first ISR. Then, a drug-coated balloon platinum-chromium alloy stent was implanted, and ISR occurred again during follow-up. The article discusses this special case and clinically relevant management options. This case highlights a scenario with refractory in-stent restenosis persisting despite various treatment strategies, including stents with different metal components, drug-coated balloons, and intensive drug therapy.