Preclinical Serial Assessment at 6 Months of Sirolimus-Eluting Bioresorbable Poly-L-Lactic Acid (PLLA) Coronary Stents Compared with Metallic Sirolimus-Eluting Stents in a Porcine Model

Purpose: Drug-eluting Bioresorbable Scaffolds or stents (BRSs) may change drastically percutaneous coronary revascularization. This study focused on multi-imaging modality assessment in parallel with histopathology for BRSs. Methods: The effects of fully bioabsorbable sirolimus-eluting Poly-L-Lactic Acid (PLLA) stents (BSES) were evaluated in a porcine coronary model. Cobalt chromium-based Sirolimus-Eluting Stents (CSES), were used as control stents. A total of 32 porcines were treated with 64 stents (BSES 32 and CSES 32,randomly impalanted into Coronary Arteries (RCA,LCXor LAD)). The Quantitative Coronary Angiography (QCA) and Optical Coherence Tomography (OCT) at 14,28,90 and180days were followed-up. Neointima formation and endothelial recovery were measured by histomorphometry and Scanning Electron Microscopy (SEM). Results: At 6 months, no significant differences in the angiographic stenosis (%) were seen for the BSES and CSES (18.7 vs. 12.7; p =0.111). OCT analysis of cross sections and struts demonstrated similar neointimal thickness (0.17±0.04mm vs. 0.20±0.02 mm; p=0.11) and in-stent area obstruction (25.63±3.36% vs. 22.71±2.87%; p=0.08), respectively. By histomorphometry,there was no significant difference in inflammation and injury scores and neointimal area (NA), lumen area (LA) and Internal Elastic Lamina (IEL)at 14,30,90 days between two stents. By SEM, at 30 days, the struts surface had been almost completely endothelialized for both stents. Conclusions: The fully bioabsorbable sirolimus-eluting PLLA stents (BSES) demonstrated a similar neointimal response and recoil as metallic DES (CSES) at least 90 days. BSES had shown noninferiority to the metallic one in safety and efficacy in porcine model, which hold the promise for further clinical study.