Comparison of acute thrombogenicity and albumin adsorption in three different durable polymer coronary drug-eluting stents

Background: The relative thrombogenicity and albumin adsorption and retention of different durable polymers used in coronary stents has not been tested.

Aims: This study sought to compare the thromboresistance and albumin binding capacity of different durable polymer drug-eluting stents (DES) using dedicated preclinical and in vitro models.

Methods: In an ex vivo swine arteriovenous shunt model, a fluoropolymer everolimus-eluting stent (FP-EES) (n=14) was compared with two durable polymer DES, the 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 antiplatelet antibodies and a marker for inflammation and were then evaluated by confocal microscopy (CM). Albumin retention was assessed using a flow loop model with labelled human serum albumin (FP-EES [n=8], BL-ZES [n=4], EP-RES [n=4], and BMS [n=7]), and scanned by CM.

Results: The area of platelet adherence (normalised to total stent surface area) was lower in the order FP-EES (9.8%), BL-ZES (32.7%), EP-RES (87.6%) and BMS (202.0%), and inflammatory cell density 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.