Vessel response after implantation of BRS or DES Insights from invasive imaging techniques

Invasive imaging techniques including quantitative coronary angiography (QCA), intravascular ultrasound (IVUS), and optical coherence tomography (OCT) have been fundamental in describing vessel response after percutaneous coronary intervention (PCI). Fully bioresorbable scaffolds (BRS) -the fourth revolution in interventional cardiology- have been designed to realize the tenet of vascular reparative therapy. In addition, computational flow dynamics (CFD) is emerging to evaluate the physiological implication of implanted devices using current existing imaging modality(ies).
In this thesis, we evaluated vessel response after implantation of BRS or drug-eluting stent (DES) by invasive imagings including QCA, IVUS, and OCT, further extending to CFD analysis based on 3D vessel reconstruction. Quantitative analysis in IVUS indicated that expansive vessel remodelling was more frequent and intense with the BRS than with the metallic DES, whereas CFD analysis suggested a different impact of shear stress on vessel remodelling in vessels implanted with BRS and those with DES. Absence of caging in BRS therapy could be one of the factors leading to these results. We also found that scaffold sizing, device asymmetry and eccentricity had a different impact at early and late clinical outcomes in patients who underwent PCI using BRS. Neointimal growth was associated with low shear stress created behind thick BRS struts; however, a thin-strut next-generation BRS showed comparative shear stress as contemporary DES. Although BRS is currently not recommended for clinical use, careful consideration should be given before making a general recommendation of BRS use as a “class”, as future developments of BRS with improved mechanical properties are expected.