COMPARISON OF SELF-EXPANDING POLYETHYLENE TEREPHTHALATE AND METALLIC STENTS IMPLANTED IN PORCINE ILIAC ARTERIES

Purpose: Comparison of the biocompatibility of self-expanding polyethy lene terephthalate (PET) stents with self-expanding metallic stents (W allstents). Methods: Diameter- and length-matched PET stents and Walls tents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographicall y and with intravascular ultrasound immediately after stent implantati on. The angiographic stented lumen diameter was measured using quantit ative vessel analysis before, immediately after stenting, and at 6-wee k follow-up. Cross-section histopathology and area morphometry were pe rformed. Results: Immediately poststenting, intravascular ultrasound r evealed proximal dislocation of 5 of the 13 PET stents, whereas all me tal stents were firmly embedded at the implantation site. At 6-week fo llow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diamete r within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p < 0.02). This observat ion was confirmed by postmortem morphometry, wherein the PET-stented v essel segments a diameter stenosis of 40% was measured vs only 9% in t he metallic stents (p < 0.0001). Conclusion: PET-stent deployment is d ifficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neo intimal proliferation than metallic stents.