Towards a Digital Twin of Coronary Stenting: A Suitable and Validated Image-Based Approach for Mimicking Patient-Specific Coronary Arteries

Considering the field of application involving stent deployment simulations, the exploitation of a digital twin of coronary stenting that can reliably mimic the patient-specific clinical reality could lead to improvements in individual treatments. A starting step to pursue this goal is the development of simple, but at the same time, robust and effective computational methods to obtain a good compromise between the accuracy of the description of physical phenomena and computational costs. Specifically, this work proposes an approach for the development of a patient-specific artery model to be used in stenting simulations. The finite element model was generated through a 3D reconstruction based on the clinical imaging (coronary Optical Coherence Tomography (OCT) and angiography) acquired on the pre-treatment patient. From a mechanical point of view, the coronary wall was described with a suitable phenomenological model, which is consistent with more complex constitutive approaches and accounts for the in vivo pressurization and axial pre-stretch. The effectiveness of this artery modeling method was tested by reproducing in silico the stenting procedures of two clinical cases and comparing the computational results with the in vivo lumen area of the stented vessel

Focus on the research utility of intravascular ultrasound - comparison with other invasive modalities

Intravascular ultrasound (IVUS) is an invasive modality which provides cross-sectional images of a coronary artery. In these images both the lumen and outer vessel wall can be identified and accurate estimations of their dimensions and of the plaque burden can be obtained. In addition, further processing of the IVUS backscatter signal helps in the characterization of the type of the plaque and thus it has been used to study the natural history of the atherosclerotic evolution. On the other hand its indigenous limitations do not allow IVUS to assess accurately stent struts coverage, existence of thrombus or exact site of plaque rupture and to identify some of the features associated with increased plaque vulnerability. In order this information to be obtained, other modalities such as optical coherence tomography, angioscopy, near infrared spectroscopy and intravascular magnetic resonance imaging have either been utilized or are under evaluation. The aim of this review article is to present the current utilities of IVUS in research and to discuss its advantages and disadvantages over the other imaging techniques

PI16 is a shear stress and inflammation-regulated inhibitor of MMP2

Raised endothelial shear stress is protective against atherosclerosis but such protection may be lost at sites of inflammation. We found that four splice variants of the peptidase inhibitor 16 (PI16) mRNA are among the most highly shear stress regulated transcripts in human coronary artery endothelial cells (HCAECs), in vitro but that expression is reduced by inflammatory mediators TNFα and IL-1β. Immunohistochemistry demonstrated that PI16 is expressed in human coronary endothelium and in a subset of neointimal cells and medial smooth muscle cells. Adenovirus-mediated PI16 overexpression inhibits HCAEC migration and secreted matrix metalloproteinase (MMP) activity. Moreover, PI16 inhibits MMP2 in part by binding an exposed peptide loop above the active site. Our results imply that, at high endothelial shear stress, PI16 contributes to inhibition of protease activity; protection that can be reversed during inflammation

Angiographic Thrombus Burden Classification in Patients With ST-Segment Elevation Myocardial Infarction Treated With Percutaneous Coronary Intervention

The presence of thrombus is associated with adverse clinical outcomes. Our aim was to develop a classification of thrombus burden (TB) in patients with ST-segment elevation myocardial infarction (STEMI). Methods. We retrospectively analyzed 900 consecutive patients treated with percutaneous coronary intervention for STEMI. Drug-eluting stents were used in 90.1%. TB was graded (G) as G0 = no thrombus, G1 = possible thrombus, G2 = small [greatest dimension 1/2 but = 2VD), G5 = unable to assess TB due to vessel occlusion. Patients with G5 were reclassified to a thrombus category after flow achievement either with a guidewire or a small (1.5 mm) balloon. The incidence of major adverse cardiac events (MACE) - defined as death, myocardial infarction and infarct-related artery revascularization - was computed using the Kaplan-Meier method. Results. Median duration of follow-up was 18.5 months. G5 patients constituted 57.7% of all patients and reclassification was achieved in 97.9%. TB after reclassification was G0, 8.1%; G1, 19%; G2, 24.5%, G3, 16.6%, G4, 30%, G5, 1.9%. The 2-year cumulative MACE-free survival was comparable in G1, G2, G3 (84.5%, 85.9% and 87% respectively, p = 0.83), while G0 (75.8%) and G4 (75%) did significantly worse (p = 0.001). After stratification in two groups of small (G0-3) and large (G4) TB, the latter was found to be an independent predictor for 2-year mortality (HR: 1.66, 95% CI: 1.04-2.68, p = 0.035) and MACE rate (HR: 2.04, 95% CI: 1.44-2.88, p = 2 VD) is a significant independent predictor for mortality and MACE