Coronary Artery Stenting Affects Wall Shear Stress Topological Skeleton.

Despite the important advancements in the stent technology for the treatment of diseased coronary arteries, major complications still affect the postoperative 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. This study aims to analyze the impact that a deployed coronary stent has on the WSS topological skeleton. Computational fluid dynamics (CFD) 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 exerted proximal to the stent struts and a WSS expansion action distal to the stent struts. This WSS action pattern was independent from the stent design. In conclusion, these findings could contribute to a deeper understanding of the hemodynamics-driven processes underlying ST and ISR.

Quantitative flow ratio as a new tool for angiography-based physiological evaluation of coronary artery disease: a review.

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.

Lay abstract Coronary arteries are the main vessels that carry blood and oxygen to the heart muscle, ensuring its functionality. In cardiology, coronary stenoses are defined as pathological narrowing of one or more of these vessels, which can lead to a critical reduction in blood flow, ischemic problems and myocardial infarction. Currently, percutaneous coronary intervention is considered the first-line treatment of myocardial infarction. This technique consists of a procedure in which the stenosis is resolved and proper blood flow is restored thanks to balloon inflation and stent implantation through a percutaneous procedure performed under local anesthesia. Coronary angiography was, for many years, the only available tool to diagnose and assess the consequences of coronary atherosclerosis, becoming the standard reference in the study of ischemic heart disease, allowing us to routinely describe the severity of coronary stenosis or the severity of the disease based on the number of vessels affected. Subsequently, the introduction of invasive methods to assess coronary physiology allowed us to obtain a precise assessment regarding the physiological impact of stenoses located in main vessels while demonstrating the poor diagnostic performance of angiography to assess the functional impact of these stenoses. Among these coronary physiology techniques, quantitative flow ratio has recently been the object of many investigations. In contrast to invasive techniques that can be performed only by advancing a wire into the coronary artery, quantitative flow ratio allows us to perform a functional evaluation of coronary stenoses on the basis of angiographic data only. Given its potential, this work will summarize the basics of quantitative flow ratio, the main validation studies and its current and future applications in interventional cardiology.

Anatomical and functional healing after resorbable magnesium scaffold implantation in human coronary vessels: A combined optical coherence tomography and quantitative flow ratio analysis.

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 mm2 ) significantly decreased compared to mean LA recorded immediately after PCI (8.12 ± 1.89 mm2 ; 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 (+0.73mm2 [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.

PK Papyrus coronary stent system: the ultrathin struts polyurethane-covered stent.

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.

Role of Invasive and Non-invasive Imaging Tools in the Diagnosis and Optimal Treatment of Patients with Spontaneous Coronary Artery Dissection.

PURPOSE OF REVIEW: Spontaneous coronary artery dissection (SCAD) is a serious non-atherosclerotic disease, most frequently presenting as an acute coronary syndrome and affecting female patients. Considering that diagnosis of SCAD is often elusive, and its interventional treatment is associated to a higher rate of complications than obstructive atherosclerotic disease, we aim to review all the imaging tools currently available for the optimal diagnosis and treatment of this condition. RECENT FINDINGS: The developments in both invasive and non-invasive imaging alternatives to coronary angiography, such as intravascular ultrasound, optical coherence tomography, and computed coronary angiography, have largely contributed to appraise the epidemiology of SCAD, understand its causative pathophysiological mechanisms, and improve our ability to confirm doubtful cases of SCAD. Intracoronary imaging is also a valuable in deciding the best therapeutic approach and in guiding interventions in those patients requiring percutaneous treatment. Furthermore, non-invasive imaging is a key tool in ruling out significant extracoronary vascular abnormalities which frequently occur in patients with underlying conditions like fibromuscular dysplasia who develop SCAD. Main imaging tools employed in SCAD cases could have advantages and drawbacks. Focusing on different types of SCAD, operators should be able to choose the best imaging technique for diagnosis, management, and follow-up.