Bioresorbable Vascular Scaffolds (BVS) are polymer-based materials implanted in the coronary arteries in order to treat atherosclerotic lesions, based on the concept that once the lesion has been treated, the material of the implanted stent will undergo a process of gradual resorption that will leave, in several years, the vessel wall smooth, free of any foreign material and with its vasomotion restored. However, after the first enthusiastic reports on the efficacy of BVSs, the recently published trials demonstrated disappointing results regarding long-term patency following BVS implantation, which were mainly attributed to technical deficiencies during the stenting procedure. Intracoronary imaging could play a crucial role for helping the operator to correctly implant a BVS into the coronary artery, as well as providing relevant information in the follow-up period. This review aims to summarize the role of intracoronary imaging in the follow-up of coronary stents, with a particular emphasis on the role of intravascular ultrasound and optical coherence tomography for procedural guidance during stent implantation and also for follow-up of bioabsorbable scaffolds.

Background: Computed tomography angiography (CTA) presents important limits in in-stent restenosis (ISR) evaluation in case of metallic coronary stents, due to the artifacts determined by stent struts, which alter in-stent plaque analysis. In case of bioresorbable scaffolds, stent strut resorption allows accurate evaluation of the vessel wall. Aim of the study: This study aims to compare the feasibility of CTA as a follow-up imaging method for ISR diagnosis following elective PTCA procedures, between bioresorbable scaffolds and metallic coronary stents. Material and methods: We conducted a prospective, observational study on 73 patients with elective PTCA procedures in their medical history, in whom 113 stents were assessed via CTA in order to diagnose ISR. Based on stent type, the patients were divided into two groups: Group 1 -patients with bioresorbable vascular scaffolds (BVS) (n = 30); and Group 2 -patients with bare metal stents (BMS) (n = 43). Plaque analysis was possible only in the BVS group with a post-processing research-dedicated software, Syngo.via Frontier, which identified plaque morphology and virtual histology composition. Results: After CTA evaluation, the BVS group presented a significantly higher incidence of severe coronary artery disease (CAD) (Group 1 -73% vs. Group 2 -30%, p <0.0001). The proximal part of the right coronary artery (RCA) presented a significantly higher percentage of metallic stents (14% BMS vs. 2% BVS, p = 0.0029). The comparative analysis of CTA sensibility for the visual evaluation of ISR identified a significantly higher percentage of diagnostic CT evaluations in the BVS group (Group 1 -94% vs. Group 2 -76.19%, p = 0.0006). CTA evaluation provided the most accurate results for the 3.0 and 3.5 mm devices. Regarding CTA sensibility for ISR diagnosis, the BVS group presented the smallest incidence of non-diagnostic CT evaluations. Conclusions: CTA evaluation of bioresorbable scaffolds is superior to metallic stent assessment, the latter being influenced by numerous sources of error dependent mainly on the presence of the metal structure.

Introduction: The coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with an inflammatory and prothrombotic state that increases the risk of thromboembolic events. High levels of D-dimer are associated with the severity of the disease and acute pulmonary embolism (PE) is the most common thrombotic complication. Material and methods: We analyzed a series of four cases of COVID-19 in young patients (under 45 years) who developed PE with a delay of two to four weeks after hospital discharge. Results: These patients had elevated D-dimer (at least 10 times the upper limit of normal) at the initial admission and at the time of the PE diagnostic, while other parameters which involved inflammation and coagulation (C-reactive protein - CRP; lactate dehydrogenase - LDH; fibrinogen; international normalized ratio - INR) were normal. There were no pre-existing risk factors for PE and all the patients were anticoagulated with prophylactic intermediate doses of enoxaparin. Conclusions: PE is a complication of the COVID-19 disease which may occur later, especially in young patients with no other risk factors for the condition. The highly elevated levels of D-dimer at COVID-19 admission seem to be associated with the post-discharge apparition of PE. This data suggests the role of extended anticoagulation in selected COVID-19 patients and warrants further investigations.

Background:Myocardial revascularization procedures have undergone important developments over the last decades, which led to a major shift in current clinical practice and therapeutic guidelines across the world. Bare metal and drug-eluting stents present several limitations, all centered on the concept of disturbed coronary hemodynamics after implantation, which can be surpassed by bioresorbable vascular scaffolds (BVS). BVSs are fourth-generation stents used in coronary revascularization procedures, but despite all the promising initial results published on their efficiency, several clinical trials have reported unsatisfactory results, and the main explanation was accredited to improper implantation method. Shear stress is a central element of intravascular homeostasis; it controls vascular remodeling, as well as the development, progression, and destabilization of atheromatous plaques. This studyaimsto assess the role of in-stent flow hemodynamics (evaluated by computational determination of shear stress via coronary CT imaging) in predicting the clinical evolution following BVS implantation.Material and methods:This case-control observational study will include patients with BVSs implanted at least 12 months prior to randomization. Each patient will undergo a complete evaluation of the demographic and clinical characteristics, cardiovascular risk factors, and imaging acquisitions via coronary CT angiography, based on which the endothelial shear stress will be calculated before and after BVS implantation. Post-processing of CT imaging data will evaluate the shear stress and the composition of the coronary plaques along the entire coronary tree. The primary endpoint will be the major adverse cardiovascular events (MACE) in patients with altered vs. non-altered BVS-related shear stress, and the secondary endpoints will comprise evaluating the rate of progression of stent resorption and progression of shear stress alteration.Conclusions:The findings of the STAFF study can be extremely useful in clinical practice for providing an answer to a key question that is still under debate: why do BVSs fail and how can we prevent this?.