Safety and efficacy of a novel abluminal groove‐filled biodegradable polymer sirolimus‐eluting stent for the treatment of de novo coronary lesions: Final five‐year results of the patient‐level pooled analysis from the TARGET I and TARGET II trials

Sirolimus Release from Biodegradable Polymers for Coronary Stent Application: A Review

Drug-eluting stents (DESs) are commonly used for the treatment of coronary artery disease. The evolution of the drug-eluting layer on the surface of the metal stent plays an important role in DES functionality. Here, the use of biodegradable polymers has emerged as an attractive strategy because it minimizes the occurrence of late thrombosis after stent implantation. Furthermore, understanding the drug-release behavior of DESs is also important for improving the safety and efficacy of stent treatments. Drug release from biodegradable polymers has attracted extensive research attention because biodegradable polymers with different properties show different drug-release behaviors. Molecular weight, composition, glass transition temperature, crystallinity, and the degradation rate are important properties affecting the behavior of polymers. Sirolimus is a conventional anti-proliferation drug and is the most widely used drug in DESs. Sirolimus-release behavior affects endothelialization and thrombosis formation after DES implantation. In this review, we focus on sirolimus release from biodegradable polymers, including synthetic and natural polymers widely used in the medical field. We hope this review will provide valuable up-to-date information on this subject and contribute to the further development of safe and efficient DESs.

The Effects of Rapamycin on the Proliferation, Migration, and Apoptosis of Human Tracheal Fibroblasts (HTrF) and Human Tracheal Epithelial Cells (HTEpiC)

Background: Restenosis after airway stenting needs to be addressed urgently. Rapamycin has been proven to inhibit restenosis elsewhere. This study aimed at observing its effects on the respiratory tract. Methods: CCK-8, wound healing, Transwell and apoptosis assays were performed to detect the effects of rapamycin on the survival, migration, and apoptosis, respectively, of human tracheal fibroblasts (HTrF) and human tracheal epithelial cells (HTEpiC). Results: The effective concentrations of paclitaxel, mitomycin C and rapamycin on HTrF were 10⁻⁷–10⁻⁴ mol/L, 10⁻⁶–10⁻⁴ mol/L, and 10⁻⁵–10⁻⁴ mol/L, respectively. At the effective concentrations, the inhibition rates of paclitaxel on HTEpiC were (43.03 ± 1.12)%, (49.49 ± 0.86)%, (55.22 ± 1.43)%, and (93.19 ± 0.45)%; the inhibition rates of mitomycin C on HTEpiC were (88.11 ± 0.69)%, (93.82 ± 0.96)%, and (94.94 ± 0.54)%; the inhibition rates of rapamycin on HTEpiC were (10.19 ± 0.35)% and (94.55 ± 0.71)%. At the concentration of (1–4) × 10⁻⁵ mol/L, the inhibition rate of rapamycin on HTrF was more than 50%, and that on HTEpiC was less than 20% (p < 0.05). Conclusions: Compared to paclitaxel and mitomycin C, rapamycin had the least effect on HTEpiC while effectively inhibiting HTrF. The optimum concentration range was (1–4) × 10⁻⁵ mol/L.

Bioresorbable polymer and durable polymer metallic stents in coronary artery disease: a meta-analysis

BACKGROUND

Literature on bioresorbable-polymer-stents (BPS) and second-generation durable-polymer-stents (DPS) in percutaneous coronary intervention (PCI) for all comer CAD is conflicting.

METHODS

Randomized controlled studies comparing PCI among BPS and second-generation DPS were identified up until May-2020 from online databases.  Primary outcomes included are all-cause myocardial infarction (MI), cardiac-death, target-vessel-revascularization (TVR), target-vessel MI (TVMI), and stent-thrombosis (ST). Random effect method of risk ratio and confidence interval of 95% was used.

RESULTS

25 prospective randomized controlled trials with 31,822 patients (BPS n = 17,065 and DPS n = 14,757) were included in the study. Follow-up ranged between a minimum of 6 months to more than 5 years. Cardiac death (RR 1.02, 95% CI 0.89-1.45, p = 0.16) was comparable in BPS and second-generation DPS. Risk of all-cause MI was similar between BPS and DPS (RR 0.97, 95% CI 0.84-1.11, p = 0.73). TVMI (RR 0.88, 95% CI 0.69-1.11, p = 0.33) and ST rates were also comparable in BPS and DPS groups (RR 1.06, 95% CI 0.80-1.40, p = 1.00). Overall TVR had comparable outcomes between BPS and DPS (RR 0.95, 95% CI 0.79-1.14, p < 0.001); however, higher TVR was seen among BPS group at follow-up of ≥5 years (RR 1.39, 95% CI 1.12-1.14, p = 0.02). Bias was low and heterogeneity was moderate.

CONCLUSION

Patients undergoing PCI treated with BPS had comparable outcomes in terms of cardiac death, TVR, ST, TVMI, and all-cause MI to patients treated with second-generation DPS; however, BPS had higher rates of TVR for follow-up of ≥5-years.

Increased incidence of serious late adverse events with drug-eluting stents when compared with coronary artery bypass surgery: a cause of concern

Percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) in pre-drug-eluting stents (DESs) era, randomized trials and meta-analysis showed that the extension of coronary artery disease was not associated with a better survival with CABG, and only diabetic patients had an inferior survival with PCI. After the introduction of DES, we would expect a substantial improvement in PCI results compared with CABG, narrowing the gap between both revascularization strategies, However, on the contrary, most randomized studies between DES and CABG showed that rate of recurrences remained and there is an unexpected increased of late serious adverse events including spontaneous myocardial infarction and death. In this review, we try to described each of these problems and find out explanations for these new findings searching for potential solutions.