Efficacy and safety of a novel nano-porous polymer-free sirolimus-eluting stent in pigs

Abstract

Background Drug-eluting stents represent a major advance in interventional cardiology. However, the current drug-eluting stents have significant limitations. One of the major problems is very late stent thrombosis, which is likely caused by inflammation and a hypersensitivity reaction related to a polymer on the stent. A polymer-free sirolimus-eluting stent with a unique nano-porous surface has been developed. This study aimed to evaluate this novel polymer-free sirolimus-eluting stent for its efficacy and safety in a pig model. Methods Stents were directly coated with sirolimus (a drug concentration of 2.2 μg/mm2 on the stent surface). The polymer-free sirolimus-eluting stents (PFSES) were compared to standard polymer-coated sirolimus-eluting stents (PCSES) and bare-metal stents (BMS) in 18 pigs. Results At one month the degree of neointimal hyperplasia was similar between the two sirolimus-eluting stent groups and was significantly less compared to BMS ((1.93±0.51) mm2, (1.57±0.69) mm2 vs. (4.45±1.05) mm2, P <0.05) At three months, PFSES maintained the low level of neointima ((2.41±0.99) mm2 vs. (4.32±1.16) mm2, P <0.05), whereas PCSES had developed significant neointimal proliferation similar to BMS. The inflammation level was significantly higher in PCSES when compared with BMS three months post-implantation (2.50±0.55 vs. 0.83±0.75, P <0.05) whereas PFSES showed a low level of inflammation comparable to PCSES (1.33±0.52 vs. 2.50±0.55, P <0.05). Conclusion The PFSES is effective and safe, and appears to be superior to standard PCSEs.