Relation of Nickel Allergy with in-Stent Restenosis in Patients Treated with Cobalt Chromium Stents

BACKGROUND In-stent restenosis (ISR) is the major limitation of percutaneous coronary stenting procedure. The elements like nickel, chromate and molybdenum are known to cause contact allergy. Hypersensitivity reaction, against these metal ions, may be one of the reasons of ISR. Cobalt chromium coronary stents, which are increasingly being used in percutaneous coronary interventions, have more nickel amount than the stainless steel stents. OBJECTIVE We aimed to investigate the association between nickel hypersensitivity reaction and ISR in patients treated with cobalt chromium coronary stents. METHODS Epicutaneous patch tests for nickel were applied to 31 patients who had undergone elective cobalt chromium coronary stent implantation and had ISR in control angiogram. Thirty patients, without ISR, were included as the control group. Patch test results and other clinical variables were compared. RESULTS There was no statistically significant difference of the mean age, sex, body mass index, rate of hypercholesterolemia, diabetes, hypertension and smoking between the patients with and without ISR. All other lesion characteristics were similar in the 2 groups. According to the patch test results, 7 patients had nickel contact allergy. All of these patients were in the ISR group, which was statistically significant (p<0.006). CONCLUSION Patients treated with cobalt chromium coronary stents and had ISR were found to have significantly more nickel allergy than the control group. Nickel allergy may play role in restenosis pathophysiology.