Permanent polymer of drug eluting stents increases eosinophil cationic protein levels following percutaneous coronary intervention independently of C-reactive protein

Aim: To assess eosinophil cationic protein (ECP) and C-reactive protein (CRP) serum levels at three time points according to different stent types. Methods: 54 patients (age 64 ± 10 years, male 78%), undergoing Bare Metal Stent (BMS) (n = 11), mammalian Target Of Rapamycin (mTOR)-inhibitor DES (n = 27) and mTOR-inhibitor bioabsorbable DES (BES) (n = 16) implantation for stable angina (SA) or non-ST-elevation acute coronary syndromes (NSTE-ACS), were prospectively enrolled. ECP and CRP serum levels were assessed before revascularization, at 1-month and at 1-year after the procedure. Moreover, 21 patients found to have inducible ischemia or angina symptoms at 6 month-stress test underwent 1-year follow-up (FU) angiography. Results: Baseline and 1-month ECP levels were similar among the 3 groups, whilst 1-year ECP was significantly higher in m-TOR-DES [8.61 (6.55-19.77) μg/ml] compared with m-TOR-BES [2.03 (1.78-5.53) μg/ml] and BMS-treated patients [2.23 (1.45-8.95) μg/ml] (p = 0.02), without significant difference between BES and BMS. CRP was similar among the 3 groups at all time points. 1-year ECP significantly correlated with late loss in patients undergoing FU angiography (r = 0.64, p = 0.002), while CRP did not (p = NS). Conclusions: Our finding suggests that mTOR-DES stent type is associated with an increase of ECP levels at 1-year, possibly reflecting a persistent eosinophil activation triggered by permanent polymer.