<b><i>Aims:</i></b> Percutaneous coronary intervention is routinely performed to treat occlusive coronary artery disease. Coronary perforation is a potential complication and can be treated with a stent graft. Current stent grafts are associated with high restenosis rates. We tested the safety and feasibility of biodegradable stent grafts in pig and rabbit models. <b><i>Methods and Results:</i></b> Stent grafts were examined in pig coronaries with repeated OCT imaging for 42 days. Novel biodegradable coatings were applied on a bare metal stent by either an electrospinning (ES) or dip coating (DC) method. A completely biodegradable system was made by ES coating a magnesium-based stent. A commercially available stent graft served as a control. ES devices showed less restenosis (44.3 ± 8.8 vs. 59.1 ± 11.1% in controls, <i>p</i> < 0.05) and smaller reduction in minimum lumen area (44.3 ± 13.4 vs. 64.4 ± 13.6% in controls, <i>p</i> < 0.05) at day 42. DC devices occluded during follow-up. ES devices showed recanalization through the graft wall at day 42. Feasibility of the ES and DC devices was evaluated in pig coronary aneurysms and rabbit aortic perforation models and sealed aneurysms and perforations without complications. <b><i>Conclusions:</i></b> Recanalization of the graft wall improves biocompatibility. Biodegradable stent grafts may present an alternative to permanent implants by showing reduced restenosis at day 42.
Introduction: Biodegradable stents present challenges during percutaneous coronary intervention (PCI) because they are typically radiolucent. For the same reason they cannot be visualized in vivo with clinical CT. By impregnating a contrast agent in the stents’ polymer coating, the stents can be seen during PCI and their degradation can be tracked in vivo using serial CT imaging. We evaluated the degradation of a polymer coated magnesium (Mg) stent in a bioreactor using dual energy microCT. Methods: Bare Mg stents with 125 μm strut thickness were coated with either a mixture of poly(lactic-co-glycolic acid) (PLGA) and triiodobenzoic acid (TIBA) or PLGA and iodinated dendrimer (ID), deployed in latex tubing, and imaged using high resolution microCT (eXplore CT120, GE) at both 80kVp and 120kVp. Stents were exposed to physiological flow in a bioreactor for 5 days, removed and dual energy microCT was repeated using same protocol. Dual energy images were processed using a custom Matlab algorithm, and the iodinated polymer was digitally segmented from the Mg struts. Results: Images of stents at baseline coated with both PLGA-ID and PLGA-TIBA showed a marked increase in CT attenuation. Images of degraded stents coated with PLGA-TIBA showed a loss of attenuation in the polymer coating but little degradation, which suggests the small TIBA molecules was not retained in the polymer. Using dual energy CT enabled segmentation of the struts and polymers. Conclusions: We have demonstrated that the radio-opacity of polymer-coated biodegradable stents can be improved with the addition of an X-ray contrast agent during the process of polymer coating with microCT. The results suggest that the degradation of biodegradable stents could be tracked in vivo. This approach could help with stent deployment and determine when the standard dual anti-platelet therapy can be stopped based on degradation as assessed with dual energy CT.
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