Serial intravascular ultrasonographic measurements after implantation of biodegradable polymer-coated stents in porcine coronary arteries.

Background: Biodegradable stent coatings provide a potential for local drug delivery at the time of vascular injury, while possible tissue toxicity is avoided through constant degradation, leaving behind a bare metal stent.

Design: Serial three-dimensional (3D) intravascular ultrasonographic results on bare Megaflex stents and biodegradable polymer-coated Megaflex stents (Hyper stents) (Eurocor, Bonn, Germany) were compared 1 and 4 weeks after intracoronary implantation in pigs.

Methods: Under general anaesthesia, the left anterior descending and circumflex coronary arteries of domestic pigs were stented with Megaflex and Hyper stents, using right femoral artery access. Control coronary angiography and intravascular ultrasonography (IVUS) were performed 1 and 4 weeks after stent implantation using left femoral artery access and right carotid artery access. After recording of angiographic and IVUS data, the pigs were allowed to recover.

Results: The 1- and 4-week IVUS follow-ups revealed less neointima formation with Hyper stents than with Megaflex stents: 1-week intimal volume, 11.8+/-0.93 compared with 15.02+/-4.18 mm3, P=0.065; intimal area, 0.81+/-0.06 compared with 1.1+/-0.16 mm2, P =0.003; maximal intimal thickness, 0.12+/-0.01 compared with 0.14+/-0.02 mm, P =0.049; 4-week intimal volume, 12.4+/-1.77 compared with 27.32+/-12.79 mm3, P =0.016; intimal area, 0.82+/-0.12 compared with 1.95+/-0.65 mm2, P=0.003; and maximal intimal thickness, 0.13+/-0.04 compared with 0.30+/-0.10 mm, P=0.003.

Conclusions: Implantation of biodegradable polymer-coated (Hyper) stents results in significantly less neointima formation 1 and 4 weeks after intracoronary implantation than with bare Megaflex stents. Taking advantage of the good collateralization of femoral and carotid arteries of pigs, the use of different arterial accesses allows serial angiographic and 3D IVUS measurements on neointimal development without sacrificing the animals.