Surgery after drug-eluting stent implantation: it's not all doom and gloom!

Blood-repellent and anti-corrosive surface by spin-coated SWCNT layer on intravascular stent materials

Despite intravascular bare metallic stents (BMS) being indispensable products in cardiovascular surgery, they face in-stent restenosis (ISR), resulting in stent failure or secondary surgical operation necessity. Accumulation or corrosion processes are key factors that promote ISR development in a vascular pathway, including an intravascular stent. The ISR can be inhibited by increasing the blood-repellency, and electrochemical corrosion resistance features using surface modification techniques on intravascular stent materials. In this study, Single-Walled Carbon Nanotube (SWCNT) structures were deposited using the spin-coating method on stent specimens made of 316L, 316LVM, CoCr-alloy, and Ti-alloy. Hydrophobicity and blood-repellency functions of coated and uncoated specimens were analysed by the Contact Angle (CA) values for distilled water (DIW), glycerol, blood plasma, and total-blood droplets using a computer-controlled goniometer system. Using a potentiostat, the electrochemical corrosion resistance features were analysed from obtained Electrochemical Impedance Spectroscopy (EIS) and Tafel curves in 37 °C Simulated Body Fluid (SBF) mimicking the human blood plasma. Due to the CA values below 90°, the repellency limit for hydrophobicity and blood-repellency, bare specimens performed hydrophilic and blood-philic features. However, SWCNT coating increased the repellency functions to 95° for DIW and 96° for total blood. The electrochemical corrosion resistance analysis showed that 1.433 kΩ cm² polarization resistance and 1.07 kΩ cm² electrochemical impedance of bare specimens increased to 142.8 kΩ cm² and 141.3 kΩ cm² by SWCNT coating. These corrosion resistance enhancements led to ratios of 78.13% inhibition in the corrosion rate and mass loss rate per year for SWCNT-coated 316LVM specimens. The maximum inhibition efficiency was observed for SWCNT-coated 316LVM specimens with a ratio of 87.92%. Obtained results indicate that SWCNT coating of the intravascular stents can inhibit the ISR risks of the BMS group.

Influences of Stent Design on In-Stent Restenosis and Major Cardiac Outcomes: A Scoping Review and Meta-Analysis

Thanks to the developments in implantable biomaterial technologies, invasive operating procedures, and widespread applications especially in vascular disease treatment, a milestone for interventional surgery was achieved with the introduction of vascular stents. Despite vascular stents providing a solution for embolisms, this technology includes various challenges, such as mechanical, electro-chemical complications, or in-stent restenosis (ISR) risks with long-term usage. Therefore, further development of biomaterial technologies is vital to overcome such risks and problems. For this purpose, recent research has focused mainly on the applications of surface modification techniques on biomaterials and vascular stents to increase their hemocompatibility. ISR risk has been reduced with the development and prevalent usage of the art technology stent designs of drug-eluting and biodegradable stents. Nevertheless, their problems have not been overcome completely. Furthermore, patients using drug-eluting stents are faced with further clinical challenges. Therefore, the bare metal stent, which is the first form of the vascular stent technology and includes the highest ISR risk, is still in common usage for vascular treatment applications. For this reason, further research is necessary to solve the remaining vital problems. In this scoping review, stent-based major cardiac events including ISR are analyzed depending on different designs and material selection in stent manufacturing. Recent and novel approaches to overcome such challenges are stated in detail.

Antiplatelet Therapy in Patients Without a Coronary Stent and Mortality After Noncardiac Surgery

BACKGROUND

This study aimed to investigate the association between perioperative antiplatelet (anti-PLT) therapy and 90-d mortality after elective noncardiac surgery.

MATERIALS AND METHODS

This retrospective cohort study analyzed the medical records of adult patients aged 18 y and older who were admitted to a single tertiary academic hospital between January 1, 2012 and December 31, 2018 for planned elective noncardiac surgery. All patients with a history of coronary artery stent insertion before the day of surgery were excluded from the analysis. Propensity score matching and conditional logistic regression analysis were used for statistical analysis.

RESULTS

After propensity score matching, a total of 24,710 patients (12,355 in each group) were included in the final analysis. Ninety-day mortalities in the anti-PLT and non-anti-PLT groups were 0.9% (107/12,355) and 1.2% (143/12,355), respectively. The anti-PLT group showed significantly lower odds for 90-d mortality (by 27%) than the non-anti-PLT group (odds ratio, 0.73; 95% confidence interval, 0.55-0.95; P = 0.017). In the sensitivity analysis of the anti-PLT group classified according to the drug type and combination, the aspirin and clopidogrel subgroups significantly showed 23% and 41% lower odds for 90-d mortality compared with the non-anti-PLT group, respectively. The dual anti-PLT groups showed no significant difference in 90-d mortality (P = 0.658).

CONCLUSIONS

Perioperative anti-PLT therapy (aspirin, clopidogrel, or dual anti-PLT therapy) was associated with lower 90-d mortality after elective noncardiac surgery in adult surgical patients without a coronary stent. This association was most evident in patients on a monotherapy of aspirin or clopidogrel.

Ileal perforation caused by a fish bone shortly after drug-eluting stent implantation for acute myocardial infarction

During the past century, the incidence of myocardial infarction has markedly increased worldwide. Percutaneous coronary intervention with stent implantation is often considered as the first-choice treatment, especially in emergency cases. Current guidelines recommend delayed elective noncardiac surgery for such vulnerable patients. However, few suggestions are available regarding the exact treatment strategy for patients who have already undergone percutaneous coronary intervention but suddenly need emergent noncardiac surgery for an unrelated reason. We herein present a case involving a patient with acute myocardial infarction who had undergone implantation of a drug-eluting stent and developed an ileal perforation due to fish bone ingestion 3 days postoperatively. After carefully balancing the risks of stent thrombosis and uncontrollable bleeding, dual antiplatelet therapy and low-molecular-weight heparin were given with close monitoring. Emergency laparotomy and partial small bowel resection surgery were then performed, after which the patient eventually recovered. This case indicates a possible management strategy for patients with acute myocardial infarction complicated by emergency noncardiac surgery.