POLYMERIC STENTING IN THE PORCINE CORONARY-ARTERY MODEL - DIFFERENTIAL OUTCOME OF EXOGENOUS FIBRIN SLEEVES VERSUS POLYURETHANE-COATED STENTS

Objectives. In a porcine coronary model, fibrin film soaked for 3 h in heparin was used as a circumferential coating on a tantalum stent to assess the effect of this naturally occurring biopolymer on arterial h ealing. The results were compared with those obtained with medical gra de polyurethane coated stainless steel stents. Background. Thrombus pl ays an important role in healing after arterial injury and may affect the development of neointimal hyperplasia. Manipulation of the initial thrombus may alter the healing response. To study this, we placed a t emplate of fibrin in a porcine coronary artery restenosis model. Metho ds. Thirty-four fibrin film stents were delivered in 20 swine. Oversiz ing was avoided, to prevent deep arterial injury, by placement of opti mally sized stents. Initial patency of the stented vessel was confirme d by angiography. Results. Three fibrin-stented swine died within 48 h ; in each, the stent was occluded with a fibrin/red blood cell mass. I n two of these three, a portion of the exogenous fibrin had become det ached from the stent and partially occluded the lumen. Of the remainin g 31 stents, all were patent at elective sacrifice at 28 days. Eighty- four percent had a diameter stenosis < 50%, and the mean (+/-SD) diame ter stenosis was 32.3 +/- 13%. There was no evidence of significant fo reign body giant cell reaction. These results contrasted with the medi cal grade polyurethane coated stents placed according to the same prot ocol without oversizing. Twelve of these stents were placed; six swine died of thrombotic occlusion within the 1st 48 h. At elective sacrifi ce at 28 days, the remaining polyurethane-coated stents were occluded by marked neointimal hyperplasia. Conclusions. Fibrin film-coated sten ts seem promising as a template for modifying the local response to ar terial injury and for potentially decreasing restenosis rates.