6-Month Follow-Up of a Novel Biodegradable Drug-Eluting Stent Composed of Poly-L-Lactic Acid and Amorphous Calcium Phosphate Nanoparticles in Porcine Coronary Artery.

We reported previously, in porcine coronary arteries, that the novel biodegradable PowerStent Absorb paclitaxel-eluting stent had improved and sustained structural strength and functional performance at one month post-implantation. To report the stent performance at 6-month follow-up. Six PowerStent Absorb and six TAXUS stents were randomly implanted in the left anterior descending and right coronary arteries of six Tibet miniature pigs. Quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) images were obtained at the time of implantation (T0) and at 6 months (T6). Two animals were sacrificed at T6 for histopathological evaluation. At T6, QCA showed that the mean luminal vascular diameter (mLD) between the PowerStent and the TAXUS stents were similar (2.36 ± 0.38 vs. 2.61 ± 0.31, respectively). Based on the IVUS analysis, the mLD and the mean lumen cross-sectional area (mCSA) in the PowerStent-treated arteries were similar between T0 and T6 (mLD: 2.74 ± 0.13 vs. 2.70 ± 0.20 and mCSA: 6.81 ± 0.62 mm2 vs. 6.68 ± 0.94 mm2). Histopathology showed that the PowerStent stents were well apposed to the vessel wall with no recoil, strut fracture and thrombus formation. The stents were fully covered with a layer of endothelial cells. At six-month post-implantation, the PowerStent Absorb stents maintained their structural strength and functional performance. The development of restenosis was controlled, no stent thrombosis was observed and the stents were fully re-endothelialized. These results suggest the PowerStent Absorb stent is safe and effective for up to 6 months when implanted in porcine coronary arteries.