Metal allergy to everolimus-eluting cobalt chromium stents confirmed by positive skin testing as a cause of recurrent multivessel in-stent restenosis.

A 54-year-old woman treated with cobalt-chromium everolimus eluting stents (CoCr-EES) for her left distal circumflex and diagonal branch lesions suffered from repeated in-stent restenosis in both lesions. Neointimal proliferation occurred rapidly and almost simultaneously in the two lesions. The cause was established to be metal allergy, as determined by patch tests which were strongly positive for bare metal stents and weakly positive for CoCr-EES. Following the third successive angioplasty, we initiated treatment with prednisolone (30 mg daily) and the anti-allergic and anti-proliferative drug tranilast (300 mg daily). An elective angiogram performed 3 months later showed no evidence of in-stent restenosis in any of the stented lesions. Furthermore, the patient has remained angina-free for 15 months. The unique features of this case include: (1) near-simultaneous repeated multivessel in-stent restenosis in a patient with skin test-documented metal allergy to cobalt-chromium stents; (2) adjunctive systemic medical therapy with prednisolone and tranilast appeared to terminate the malignant restenotic cycle.