Aims: This study sought to compare thromboresistance and albumin binding capacity of different durable polymer DESs using dedicated preclinical and in vitro models.
Methods and Results: In an ex vivo swine arterio-venous shunt model, fluoropolymer everolimus-eluting stent (FP-EES) (n=14) was compared with two durable polymer DES (BioLinx polymer coated zotarolimus-eluting stent (BL-ZES)(n=9) and a CarboSil® elastomer polymer coated ridaforolimus-eluting stent (EP-RES)(n=6)), and bare metal stents (BMS)(n=10). Stents underwent immunostaining using a cocktail of anti-platelet antibodies and a marker for inflammation and then were evaluated by confocal microscopy (CM). Albumin retention was assessed by using a flow loop model with labeled human serum albumin [FP-EES(n=8), BL-ZES(n=4), EP-RES(n=4), and BMS(n=7)] and scanned by CM. The area of platelet adherence (normalized to total stent surface area) was lower in order of FP-EES (9.8%), BL-ZES (32.7%), EP-RES (87.6%) and BMS (202.0%) and inflammatory cell densities was least for FP-EES<BL-ZES<EP-RES<BMS. Although nearly full coverage by albumin binding was shown for all durable polymer DES, FP-EES showed significantly greater intensity of albumin as compared to BL-ZES, EP-RES and BMS (FP-EES;79.0%, BL-ZES;13.2%, EP-RES;6.1%, BMS;1.5%).
Conclusions: These results suggest that thromboresistance, and albumin retention vary by polymer type and that these differences might result in different suitability for short-term dual antiplatelet therapy.