Abstract 13276: Intravascular Optical Molecular Imaging of Fibrin Deposition to Assess Vascular Healing After Coronary Stent Implantation
Objective: Stent thrombosis (ST) is a devastating complication of implanted coronary stents. Stents prone to ST are characterized by impaired healing, typified by fibrin deposition. Therefore, approaches to specifically image fibrin on stents could identify stents at risk of clinical ST. To address this unmet need, we have developed a new near-infrared fluorescence (NIRF) imaging agent (FTP11-CyAm7) for molecular imaging of fibrin. In this study, we utilize FTP11-CyAm7 in concert a newly validated intravascular NIRF-optical frequency domain imaging (OFDI) system capable of simultaneous quantitative molecular-structural imaging. Our objective is to image subacute fibrin deposition on coronary stents implanted in vivo in arteries of rabbits.
Methods: We first evaluated the specificity of FTP11-CyAm7 in human and rabbit plasma clots in vitro. Next the blood half-life of FTP11-CyAm7 was determined (n=3 rabbits). For in vivo studies, rabbits (n=4) underwent implantation of coronary bare metal stents into the iliac artery. At 5-7 days post stenting, FTP11-CyAm7 (100 nmol/kg) was injected, and intravascular NIRF-OFDI was performed over the next 2 hours. After sacrifice, ex vivo imaging, electrical stent dissolution, fluorescence microscopy (FM), and fibrin immunostaining was performed.
Results: In vitro, FTP11-CyAm7 showed a significantly higher NIRF clot-to-background ratio than a control NIRF peptide (4.1±0.6 vs. 1.7±0.1, p<0.01). The blood half-life of FTP11-CyAm7 was 10.2 minutes. Intravascular NIRF-OFDI demonstrated in vivo microscopic fibrin deposition precisely overlying stent struts and in several areas between stents (Figure). Findings were corroborated by en face FM. The in vivo NIRF fibrin signal correlated significantly with fibrin immunostaining (R=0.68, p<0.0001).
Conclusions: We demonstrate a new approach to specifically image fibrin deposition on unhealed coronary stents using in vivo NIRF-OFDI molecular imaging.
- © 2012 by American Heart Association, Inc.