Angiographic and Optical Coherence Tomography Insights into Bioresorbable Scaffold Thrombosis: Single-Center Experience

Background - As bioresorbable vascular scaffolds (BVSs) are being increasingly used in complex real-world lesions and populations, BVS thrombosis cases have been repo

Neoatherosclerosis development following bioresorbable vascular scaffold implantation in diabetic and non-diabetic swine

Background: DM remains a risk factor for poor outcome after stent-implantation, but little is known if and how DM affects the vascular response to BVS. Aim The aim of our study was to examine coronary responses to bioresorbable vascular scaffolds (BVS) in swine with and without diabetes mellitus fed a ‘fast-food’ diet (FF-DM and FF-NDM, respectively) by sequential optical coherence tomography (OCT)-imaging and histology. Methods: Fifteen male swine were evaluated. Eight received streptozotocin-injection to induce DM. After 9 months (M), 32 single BVS were implanted in epicardial arteries with a stent to artery (S/A)-ratio of 1.1:1 under quantitative coronary angiography (QCA) and OCT guidance. Lumen, scaffold, neointimal coverage and composition were assessed by QCA, OCT and near-infrared spectroscopy (NIRS) pre- and/or post-procedure, at 3M and 6M. Additionally, polarization-sensitive (PS)-OCT was performed in 7 swine at 6M. After sacrifice at 3M and 6M, histology and polymer degradation analysis were performed. Results: Late lumen loss was high (~60%) within the first 3M after BVS-implantation (P0.20). Neointimal coverage was highly heterogeneous in all swine (DM vs. NDM P>0.05), with focal lipid accumulation, irregular collagen distribution and neointimal calcification. Likewise, polymer mass loss was low (~2% at 3M, ~5% at 6M;P>0.20) and not associated with DM or inflammation. Conclusion: Scaffold coverage showed signs of neo-atherosclerosis in all FF-DM and FF-NDM swine, scaffold polymer was preserved and the vascular response to BVS was not influenced by diabetes

(PS)-OCT and corresponding histology at 6M.

<p>OCT demonstrated the development of a highly heterogeneous neointima with lipid and calcium accumulation in FF-DM and FF-NDM swine at 6 months (<b>A, L</b>), which was confirmed by histology (<b>D, I, O, S</b>; Oil-red-O). Phase retardation corresponding to tissue birefringence (<b>B, M</b>) and depolarization (<b>G, Q</b>) imaged by PS-OCT, demonstrated enhanced birefringence and depolarization (<b>C</b>) in an SMC-poor area (<b>E</b>; aSMA) with inflammation (<b>F</b>; CD45). Furthermore, PS-OCT demonstrated focal depolarization (<b>H</b>) in a collagen-poor area with loss of structure and evidence of early necrosis (<b>J, K</b>; HE, PSR). <b>N</b> shows coarse-grained high birefringence in an area with strongly circumferentially organized intimal SMCs (<b>P</b>; RF); lipid-rich, SMC-poor tissue (<b>T</b>; SMA) exhibits a more finely speckled heterogeneity, associated with a rapid loss of polarization degree (<b>R</b>). Asterisk (*) indicates guidewire artefact, arrowheads lipid, white lines calcium.</p

Corresponding QCA, OCT, NIRS and histology at 6M.

<p>QCA (<b>A</b>) demonstrates the scaffolded region (white block), with the yellow line indicating the region corresponding to the NIRS, (PS)-OCT and histology images (<b>B-G</b>). The NIRS chemogram demonstrates presence of lipid (<b>B</b>), also observed by OCT (<b>D</b>; arrowheads) that additionally demonstrates the presence of calcium (white circles). The PS-OCT phase retardation image demonstrates a finely grained pattern (<b>E</b>) consistent with lipid-rich neointima (<b>F</b>; Oil-Red-O) and active inflammation (<b>G</b>; CD45).</p

Irregular collagen distribution in the neointima.

<p>Collagen poor areas in peri-strut regions and neointima (<b>A, D</b>; Picrosirius Red) often demonstrated lipid accumulation (<b>B, E</b>; Oil-red-O), and leucocytes (<b>C, F</b>; CD45). Additionally, <b>G</b> (Picrosirius Red) demonstrates a patchy collagen poor lesion with lipid accumulation (<b>H</b>; Oil-red-O) and smooth muscle cells (<b>I</b>; aSMA). *: strut void, <b>L</b>: lumen.</p

Study design.

<p>BVS = bioresorbable vascular scaffold, FUP = follow-up, QCA = quantitative coronary angiography, PS = Polarization Sensitive, OCT = optical coherence tomography, NIRS = near-infrared spectroscopy, GPC = gel permeation chromatography.</p