Anti-CD34 capturing in coronary stenting leads to improved endothelial coverage: COMBO vs. Xience Prime

Introduction: Drug-eluting stents (DES) reduce neointimal hyperplasia (NIH) by inhibition of vascular smooth muscle cell (VSMC) proliferation. Because of their non-selective anti-proliferative effect, stent re-endothelialization is also inhibited, which may increase the risk for stent thrombosis. The COMBO stent combines an abluminal sirolimus-eluting coating with endothelial progenitor cell (EPC) capturing technology to combine intimal hyperplasia reduction with improved reendothelialization. Purpose: The aim of our study was to compare the novel COMBO stent with current standard treatment. Methods: Twelve New-Zealand White (NZW) rabbits were subjected to iliac artery stent placement. Twenty-eight days after implantation, optical coherence tomography (OCT) was performed (n=6) and tissue was harvested from the animals (n=6). Late lumen loss ratio was defined as angiographic stent diameter directly after implantation/stent diameter at twenty-eight days of follow-up. Intimal hyperplasia was assessed by both histology and OCT. Additionally, scanning electron microscopy (sEM) was performed to evaluate stent coverage. Results: Compared to EES, strut coverage was significantly higher in the COMBO stent (78.5±16.8% vs. 96.6±3.5%; p=0.043). Intimal hyperplasia did not differ between the EES and COMBO stent as assessed by OCT (0.227±0.025 mm2 vs. 0.188±0.044 mm2; p=NS) or histology (0.823±0.200 mm2 vs. 0.891±0.312 mm2; p=NS). No differences were observed in late lumen loss ratio between both EES and COMBO stent (0.95±0.027 vs. 0.94±0.024; p=NS). Conclusion: Re-endothelialization was significantly improved in the COMBO stent as compared to EES with equal inhibition of intimal hyperplasia. As stent endothelialization is a major determinant of stent thrombosis, this may reduce thrombotic events after DES implantation.