In-stent restenosis after revascularization of myocardium with drug-eluting stents is accompanied by elevated level of blood plasma eosinophil cationic protein.

The aim of this study was to assess the involvement of eosinophil cationic protein, a marker of eosinophil activation, in the development of in-stent restenosis after drug-eluting stent implantation. Follow-up angiography at 6 to 12 months was performed in 32 patients who were treated with percutaneous coronary intervention and implantation of sirolimus-eluting stents. Blood plasma levels of eosinophil cationic protein (ECP) and total immunoglobulin E (IgE) were measured by enzyme-linked immunosorbent assay and the level of C-reactive protein (hs-CRP) by high-sensitivity nephelometry. According to angiography data, in-stent restenosis occurred in 13 patients, while 19 patients did not develop it. There were no differences between the hs-CRP and IgE levels in patients with or without restenosis. In contrast, ECP level was higher in patients with restenosis compared with that in patients without restenosis [17.7 ng/mL (11.2-24.0) vs. 9.0 ng/mL (6.4-12.9), p = 0.017]. The incidence of in-stent restenoses was 63% in patients with ECP level higher than or equal to 11 ng/mL, and 19% in patients with an ECP level lower than 11 ng/mL (p = 0.019). These findings suggest that elevated eosinophil activation may play an important role in the pathogenesis of in-stent restenosis after implantation of drug-eluting stents.