The functional evaluation of coronary stenoses has obtained important clinical results in recent years, resulting in strong guideline recommendations. Nonetheless, the use of coronary wire-based functional evaluation has not yet become part of the routine in catheterization laboratories for several reasons, including the need to advance a wire into the coronary vessel to interrogate the stenosis. Angiography-derived indexes have been introduced to expand the current use of physiology to estimate the functional meaning of a stenosis on the basis of angiographic data only. The most studied and validated angiography-derived index is certainly the quantitative flow ratio. This article will summarize the basics of the quantitative flow ratio, the related validation studies and its current and future applications.

Despite the important advancements in the stent technology for the treatment of diseased coronary arteries, major complications still affect the post-operative long-term outcome. The stent-induced flow disturbances, and especially the altered wall shear stress (WSS) profile at the strut level, play an important role in the pathophysiological mechanisms leading to stent thrombosis (ST) and in-stent restenosis (ISR). In this context, the analysis of the WSS topological skeleton is gaining more and more interest by extending the current understanding of the association between local hemodynamics and vascular diseases. The present study aims to analyze the impact that a deployed coronary stent has on the WSS topological skeleton. Computational fluid dynamics simulations were performed in three stented human coronary artery geometries reconstructed from clinical images. The selected cases presented stents with different designs (i.e., two contemporary drug eluting stents and one bioresorbable scaffold) and included regions with stent malapposition or overlapping. A recently proposed Eulerian-based approach was applied to analyze the WSS topological skeleton features. The results highlighted that the presence of single or multiple stents within a coronary artery markedly impacts the WSS topological skeleton. In particular, repetitive patterns of WSS divergence were observed at the luminal surface, highlighting a WSS contraction action proximal to the struts and a WSS expansion action distal to the struts. This WSS action pattern was independent from the stent design. In conclusions, these findings could contribute to a deeper understanding of the hemodynamic-driven processes underlying ST and ISR.

The latest advances in imaging technology have provided cardiologists with additional tools to help dealing challenging scenarios. A perfect example of such cases is represented by Spontaneous Coronary Artery Dissection (SCAD), which is often difficult to recognize and whose interventional treatment is not free from complications. New techniques, such as IVUS, OCT or CCTA, have improved our ability to confirm doubtful cases of SCAD, optimize the interventional strategy and properly monitor patients after discharge. Hence, in the present review, we discuss the main imaging tools employed in SCAD cases, introducing their advantages and drawbacks and focusing on the different role they may play in SCAD diagnosis, management and follow-up

Background: No data are currently available on the process of vessel healing and long-term physiological results after implantation of resorbable magnesium-made scaffold (RMS) in human coronary arteries.Objectives: To investigate after percutaneous coronary intervention (PCI) and at 12 months follow-up (a) RMS resorption process and vessel healing, as judged by optical coherence tomography (OCT) imaging; and (b) physiological result of RMS implantation evaluated by quantitative flow ratio (QFR).Methods: All patients successfully treated with at least one RMS from July 2016 to August 2018 at 2 Italian centers were evaluated. All cases with OCT pullback and/or coronary angiography suitable for QFR analysis performed after PCI and at 12 months were included. Resorption process was analyzed at OCT in each frame reporting presence of residual struts in the vessel.Results: Forty-four patients/forty-nine lesions were included. 12-months mean lumen area (LA; 7.54 ± 3.04 mm 2 ) significantly decreased compared to mean LA recorded immediately after PCI (8.12 ± 1.89 mm 2 ; p < .01). However, LA changes did not affect the functional result of PCI with a non-ischemic QFR value (>0.80) in 98% of cases at 12-months follow-up. Protruding struts were detectable in more than half of cases and their presence was correlated with an increase in mean LA (+0.73mm 2 [95% CI 0.51-0.94], p < .001).Conclusions: RMS implantation in a real-world population lead to significant decrease in mean LA without significant functional impairment. Two different patterns of RMS resorption were recorded, whose clinical significance remains to be investigated.

In the emergency setting of a coronary vessel perforation, the knowledge of materials needed to fix it and the intrinsic quality of the device used is mandatory for the interventional cardiologist. The PK Papyrus covered stent (Biotronik AG) is an ultrathin strut (60 μm) balloon-expandable stent covered on the abluminal surface with an electrospun polyurethane matrix. It is intended to facilitate device delivery and effectively treat coronary artery perforations. In published studies, rates of successful device delivery and perforation sealing were above 90%, respectively, and most events were usually resolved with a single stent. In this review we focused on the main technical characteristics as well on the published evidence that compare its performance with other coronary covered stent.