Long-term preclinical evaluation of bioabsorbable polymer-coated drug-eluting stent in a porcine model

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Bioabsorbable polymer-based drug-eluting stents have been shown to be effective and safe in the actual practice. The objective of the present study was to evaluate a biodegradable poly-L-lactic acid (PLLA)-based sirolimus-coated stent in comparison with a commercial everolimus-eluting stent with a permanent polymer in a porcine coronary restenosis model on a short-, mid-, and long-term basis. Pigs were randomized into eight groups in which the coronary arteries (36 pigs with 72 coronary arteries) had either a sirolimus-eluting stent with PLLA (SES, n=24, follow-up after 4, 12, and 24 weeks), bare metal stent (BMS, n=12, follow-up after 4 weeks), PLLA-coated stent without a drug (PCS, n=12, follow-up after 4 weeks), or commercial everolimus-eluting stent with a permanent polymer (EES, Promus PREMIER®, n=24, follow-up after 4, 12, and 24 weeks). Histopathological analysis was performed at 4, 12, or 24 weeks after stenting. The surface morphology of the SES, visualized using an optical microscope and a scanning electron microscope, was smooth and uniform with virtually no defects. Sirolimus was released slowly over 60 days. There was no significant difference in the percent area stenosis between the SES and EES at any of the follow-up time points (13.0±8.10% in SES vs. 14.1±9.12% in EES at 4 weeks, 23.1±8.63% in SES vs. 21.3±7.92% in EES at 12 weeks, 28.2±8.20% in SES vs. 25.1±8.51% in EES at 24 weeks, each p=NS). The percent area stenosis using micro-computed tomography and intravenous ultrasound demonstrated similar restenosis rates with histopathological stenosis between the SES and EES. The SES with a biodegradable polymer was as effective as the commercial EES with a permanent polymer in inhibiting neointima proliferation at 4, 12, and 24 weeks in a porcine coronary restenosis model.