Drug-eluting stents ameliorate pulmonary vein stenotic changes in pigs in vivo.

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 ± 0.033 vs SES 0.226 ± 0.031 mm; P < 0.01; injury score 2: BMS 1.232 ± 0.244 vs SES 0.609 ± 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.