Vascular response and mechanical integrity of the new biodegradable polymer coated sirolimus-eluting PROLIM stent implanted in porcine coronary arteries.

BACKGROUND: Although durable polymer coated drug-eluting stents (DES) are standard care in percutaneous coronary interventions, new stent platforms employing biodegradable polymer based drug delivery are increasingly being used in clinical practice. AIM: To evaluate the short- (28 days) and medium-term (90 days) vascular effects of the new biodegradable polymer coated sirolimus-eluting stent - the PROLIM stent. METHODS: The objectives of the study were evaluated using standard angiographic and histological methods. In addition, the mechanical integrity of tested stents was assessed using Faxitron imaging. A total of 12 PROLIM stents, 11 biodegradable polymer only coated stents (BPCS), and 12 bare metal stents (BMS) were implanted in the coronary arteries of 16 female non-atheroslerotic domestic swine using an overstretch of 1.1:1.0. RESULTS: At 28 days, neointimal proliferation was significantly lower in the PROLIM and BMS stents compared to the BPCS stents (p ≤ 0.05). Interestingly, despite thin neointima found at this time in the PROLIM group, there was a further significant decrease in neointimal formation between 28 and 90 days (p = 0.04). Although a statistically bigger neointima was found in BPCS stents at 28 days compared to the PROLIM and BMS stents, there was a 50% decrease in the neointimal area at 90 days follow-up (p = 0.02) which reached the level seen in other groups. The endothelialisation was completed in all tested stents after 28 days. There was a significant increase of fibrin depositions in the PROLIM treated arteries at 28 days which were resorbed nearly completely at 90 days follow-up. At 28 days, the inflammatory response was found to be numerically higher in the BPCS stents (p = NS) compared to other tested groups. On the contrary, at 90 days follow-up when the degradation process of the polymer had been completed, the inflammatory reaction decreased substantially to the level seen in the PROLIM and BMS stents. Faxitron analysis of the stented arteries revealed no major abnormalities except for isolated strut fractures observed in the mid portions of two BMS stents and one BPCS stent. CONCLUSIONS: The PROLIM - a biodegradable polymer coated sirolimus-eluting stent - demonstrates very good short-term and medium-term angiographic and histological results. The lack of 'catch-up phenomenon', fast endothelialisation process, and minimal inflammatory reaction may contribute to favourable clinical outcomes using PROLIM stents.

Novel biodegradable polymer-coated, paclitaxel-eluting stent inhibits neointimal formation in porcine coronary arteries.

BACKGROUND: Biodegradable polymer-coated stents may have positive effects on arterial healing, and reduce the need for prolonged antiplatelet therapy. AIM: To assess the vascular effects of the biodegradable polymer proposed as a stent coating, as well as to evaluate inhibition of intimal hyperplasia by Biodegradable Polymer-Coated Paclitaxel-Eluting Stents (BP-PES, LUC-Chopin, Balton) in porcine coronary arteries. METHODS: A total of 19 stents were implanted into the coronary arteries of 13 pigs: seven bare metal stents (BMS), six biodegradable polymer-coated stents (PCS) and six BP-PES. Animals were followed up for 28 days. Additionally, 11 BP-PES were implanted in four pigs which were followed for 90 days. Twenty eight and 90 days after stent implantation, the control coronary angiography was performed. Subsequently, the animals were sacrificed, their hearts were extracted and the coronary arteries were isolated for further histopathological analysis. RESULTS: After 28 days, BP-PES stents effectively limited neointimal hyperplasia in comparison to the control group (LL = 0.48 +/- 0.06 for BMS vs 0.87 +/- 0.16 for PCS vs 0.15 +/- 0.05 mm for BP-PES; p < 0.05). However, at three months, a 'catch-up' effect in neointimal formation was observed. Histopathology demonstrated favourable safety, with complete endothelialisation and inflammation significantly decreased between one and three months. CONCLUSIONS: It seems that the biodegradable polymer-coated, paclitaxel-eluting stent examined in the present study is both safe and feasible. This supports the first such study in humans being conducted.