Drug-Eluting Stents Ameliorate Pulmonary Vein Stenotic Changes in Pigs In Vivo

Abstract

The outcome of stent implantation for pulmonary vein stenosis (PVS) in children remains poor. Several reports describe placing drug-eluting stents to treat PVS, but their effectiveness remains unknown. In this study, three bare-metal stents (BMSs) and three sirolimus-eluting stents (SESs) were implanted in 1-month-old pigs. The pigs were killed 8 weeks later to compare in-stent stenosis rates. The extent of neointimal thickness, as measured by injury score, was significantly less in the SES group than in the BMS group (injury score 1: BMS 0.351 + or - 0.033 vs SES 0.226 + or - 0.031 mm; P < 0.01; injury score 2: BMS 1.232 + or - 0.244 vs SES 0.609 + or - 0.208 mm; P < 0.01). The pathologic findings showed confluence of inflammatory cells around the stent wires in BMS-treated areas and granuloma formation. Granuloma formation was not seen with SES. The degree of in-stent stenosis was significantly reduced in the SES group, suggesting that the use of drug-eluting stents is an effective treatment for PVS. Because of the small sample size and the considerable variation in injury scores and balloon-to-vein ratios, future studies with larger samples are necessary.