Evaluation of coronary stents using multidetector CT

Health Care Monitoring and Treatment for Coronary Artery Diseases: Challenges and Issues

In-stent restenosis concerning the coronary artery refers to the blood clotting-caused re-narrowing of the blocked section of the artery, which is opened using a stent. The failure rate for stents is in the range of 10% to 15%, where they do not remain open, thereby leading to about 40% of the patients with stent implantations requiring repeat procedure within one year, despite increased risk factors and the administration of expensive medicines. Hence, today stent restenosis is a significant cause of deaths globally. Monitoring and treatment matter a lot when it comes to early diagnosis and treatment. A review of the present stent monitoring technology as well as the practical treatment for addressing stent restenosis was conducted. The problems and challenges associated with current stent monitoring technology were illustrated, along with its typical applications. Brief suggestions were given and the progress of stent implants was discussed. It was revealed that prime requisites are needed to achieve good quality implanted stent devices in terms of their size, reliability, etc. This review would positively prompt researchers to augment their efforts towards the expansion of healthcare systems. Lastly, the challenges and concerns associated with nurturing a healthcare system were deliberated with meaningful evaluations.

Diagnostic value of intraluminal stent enhancement in estimating coronary in-stent restenosis

Objective

In-stent restenosis (ISR) diagnosis is among the most serious complications of patients undergone stent implantation. Although coronary computed tomography angiography (CCTA) has been widely used for ISR assessing, stent narrow lumen and presence of stent's struts artifacts have limited its efficacy. The use of quantitative techniques may provide more valuable findings for ISR diagnosis. The aim of this study is to assess the predictive value of a quantitative technique of ISR estimation based on stent intraluminal enhancement derived from CCTA.

Materials and Methods

In the current study, 40 patients with the previous history of coronary artery diseases (CADs) and coronary stent placement who reexperienced CAD symptoms and referred for CCTA were assessed in 2017-2018. Stent intraluminal "enhancement value" (EV) was measured using calcium score and post-contrast images of CCTA. The cutoff point was determined using conventional invasive coronary angiography as the gold standard.

Results

Total numbers of 58 stents were evaluated, in which stent intraluminal enhancement was assessed in initial, middle, and end sites of stent, achieved cutoff points for more than 50% of ISR were 204, 168, and 204 Hounsfield units, respectively. These cutoff points had diagnostic value of 77.5% for initial part, 86% for midpart, and 81% for end part, respectively.

Conclusion

The use of quantitative method of stent intraluminal EV for ISR estimation has better diagnostic value in comparison to qualitative techniques that can help better clinical decision making. Moreover, measurements of this method are somewhat easier and also secondary artifacts of stent struts and calcified plaques would be eliminated.

CTA Evaluation of Bioresorbable Scaffolds versus Metallic Coronary Stents – a Feasibility Study

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.