Abstract 4162: Assessment of a New Biodegradable Drug Eluting Stent for the Inhibition of Neovascularisation and Neointimal Hyperplasia: An Experimental Study With Optical Coherence Tomography
Background: Vascular endothelial growth factor (VEGF) appears to be the most important mediator of neovascularisation. We assumed that inhibition of VEGF, using local delivery of bevacizumab, a monoclonal antibody specific for VEGF, could affect neovascularization and intimal hyperplasia in hypercholesterolemic rabbits.
Methods: We used 10 New Zealand white rabbits under atherogenic diet for 3 weeks. Eleven biodegradable bevacizumab-eluting stents (BES) were implanted in the distal aorta. The control group consisted of 7 New Zealand white rabbits that were treated with 7 bare metal stents covered by biodegradable polymer. All animals were treated with aspirin and clopidogrel for 4 weeks. Follow-up angiography and Optical Coherence Tomography (OCT) study were performed at 4 weeks. OCT images of each stent were analyzed and each strut was examined for apposition. A strut was defined as embedded when it was buried in the intima for more than half its thickness, protruding when apposed to the intima but not embedded, and malapposed when there was no intimal contact. Tissues were obtained for immunohistological analysis.
Results: Angiography and OCT in all stented arteries revealed no stent thrombosis and no restenosis. We acquired 121 cross-sectional images from 110 mm in the stents of the BES group and 77 cross-sectional images from 70 mm of the stents in the control group. From the total of 1103 struts in the BES group, 1075 (97.5%) were embedded, while 28 (2.5%) struts were protruding and none malapposed. In the control group, 710 struts were analyzed, of which 697 were embedded (98.1%), 13 protruding (1.9%), and none malapposed (p=NS). Mean neointimal area in the bevacizumab group was 0.15±0.09 mm2 comprising 2.45% of the lumen area, versus 0.78±0.21 mm2 and 14.3% respectively in the control group (p<0.001). Maximal intimal thickness was significantly lower in the BES group compared to the control (60±11 μm versus 135±7 μm, p<0.001). Bevacizumab-treated arterial segments had significantly decreased microvessel density compared to the control group (1.7±0.7 vessels per mm2 vs 15.5±1.2 vessels per mm2, p<0.001)
Conclusions: This study demonstrated the safety and effectiveness of a new biodegradable eluting stent in animal model.