Histopathologic Validation of Optical Coherence Tomography Findings of Non-Apposed Side-Branch Struts in Porcine Arteries

Abstract: Background. The presence of uncovered struts overlying side branch is considered to be a potential risk of stent thrombosis. The accuracy in detection of neointimal strut coverage at branch point by optical coherence tomography (OCT) has not been validated in comparison with histology. Methods. A total of 5 stents (3 drug-eluting stents and 2 bare-metal stents) were implanted in the bifurcation segment of normal coronary arteries in 4 domestic swine (weight, 25-40 kg). The animals underwent follow-up OCT at 30 days after stent implantation and were then sacrificed for histologic evaluation. The neointimal coverage of the non-apposed struts over the side branch was assessed by light microscopy. Every millimeter of the stent was specified by the OCT frame rate, and comparisons between OCT and pathologic findings were performed through precise histological-OCT frame matching. Results. OCT images at the side branch corresponded well with histological cross-sections. The tissues covering struts as assessed by OCT contained smooth muscle cells with proteoglycan-collagen matrix, but platelets are attached above the neointima in one of them on histologic examination, suggesting that most of the struts were well healed, with normal neointimal coverage. Conclusion. This study demonstrated the accuracy of OCT for the detection of neointimal coverage of non-apposed struts over the side branch.ope