Long-term outcomes of titanium-nitride-oxide coated stents and drug-eluting stents in acute coronary syndrome: A systematic review and meta-analysis

BACKGROUND

In severe cases of coronary artery disease, percutaneous coronary intervention provide promising results. The stent used could be a drug-eluting stent (DES) or a titanium-nitride-oxide coated stent (TiNOS).

AIM

To compare the 5-year effectiveness and safety of the two stent types.

METHODS

The following systematic review and meta-analysis was conducted in accordance with the preferred reporting items for systematic reviews and meta-analysis guidelines, and PubMed/MEDLINE, Scopus, and Cochrane Central were searched from inception till August 2023. Primary outcomes were major adverse cardiac events (MACE), cardiac death, myocardial infarction (MI), cardiac death or MI, and ischemia-driven total lesion revascularization (ID-TLR).

RESULTS

Four randomized controlled trials (RCT), which analyzed a sum total of 3045 patients with acute coronary syndrome (ACS) after a median follow-up time of 5 years were included. Though statistically insignificant, an increase in the ID-TLR was observed in patients receiving TiNOSs vs DESs. In addition, MI, cardiac death and MI, and definite stent thrombosis (DST) were significantly decreased in the TiNOS arm. Baseline analysis revealed no significant results with meta-regression presenting non-ST elevated MI (NSTEMI) as a statistically significant covariate in the outcome of MACE.

CONCLUSION

TiNOS was found to be superior to DES in terms of MI, cardiac death or MI, and DST outcomes, however, the effect of the two stent types on ID-TLR and MACE was not significant. A greater number of studies are required to establish an accurate comparison of patient outcomes in TiNOS and DES.

Five-Year Efficacy and Safety of TiNO-Coated Stents Versus Drug-Eluting Stents in Acute Coronary Syndrome: A Meta-Analysis

(1) Background: Percutaneous coronary interventions (PCI) in patients with acute coronary syndrome (ACS) are performed with titanium-nitride-oxide-coated stents (TiNOSs) or drug-eluting stents (DESs). The initial completion of this prospective systematic literature review (SLR) of prospective randomized controlled trials (RCTs) showed that TiNOSs are non-inferior to DESs in major adverse cardiac event (MACE) rates and present a lower risk of recurrent myocardial infarction (MI) at 1-year follow-up. This iteration of the SLR protocol performs the critical assessment of 5-year follow-up outcomes with clinical validity and generalizability assessments. (2) Methods: The previously described SLR and meta-analysis protocol, per PRISMA, Cochrane methods, and GRADE, was applied to 5-year follow-up outcomes. (3) Results: Three RCTs were eligible, comprising 1620 patients with TiNOS vs. 1123 with DES. The pooled risk ratios (RRs) and 95% confidence intervals were MACE 0.82 [0.68, 0.99], MI 0.58 [0.44, 0.78], cardiac death (CD) 0.46 [0.28, 0.76], ischemia-driven target lesion revascularization (TLR) 1.03 [0.79, 1.33], probable or definite stent thrombosis (ST) 0.32 [0.21, 0.59], and all-cause mortality (TD) 0.84 [0.63, 1.12]. The evidence certainty was high in MACE, CD, MI, and ST, and moderate in TLR and TD. (4) Conclusions: TiNOSs in ACS at 5-year follow-up appear safer than DESs and equally efficacious. The pooled RRs stratified by clinical presentation and stent type will be required to test this meta-analysis's clinical validity and generalize its results to patient populations with varying proportions of clinical presentations and DES options.

Integral Algorithms to Evaluate TiO2 and N-TiO2 Thin Films' Cytocompatibility

Titanium oxide (TiO₂) and oxynitride (N-TiO₂) coatings can increase nitinol stents' cytocompatibility with endothelial cells. Methods of TiO₂ and N-TiO₂ sputtering and cytocompatibility assessments vary significantly among different research groups, making it difficult to compare results. The aim of this work was to develop an integral cytocompatibility index (ICI) and a decision tree algorithm (DTA) using the "EA.hy926 cell/TiO₂ or N-TiO₂ coating" model and to determine the optimal cytocompatible coating. Magnetron sputtering was performed in a reaction gas medium with various N₂:O₂ ratios and bias voltages. The samples' morphology was studied by scanning electron microscopy (SEM) and Raman spectroscopy. The cytocompatibility of the coatings was evaluated in terms of their cytotoxicity, adhesion, viability, and NO production. The ICI and DTA were developed to assess the cytocompatibility of the samples. Both algorithms demonstrated the best cytocompatibility for the sample sputtered at U_bias = 0 V and a gas ratio of N₂:O₂ = 2:1, in which the rutile phase dominated. The DTA provided more detailed information about the cytocompatibility, which depended on the sputtering mode, surface morphology, and crystalline phase. The proposed mathematical models relate the cytocompatibility and the studied physical characteristics.

Titanium-nitride-oxide-coated coronary stents: insights from the available evidence

Coating of stent surface with a biocompatible material is suggested to improve stent safety profile. A proprietary process was developed to coat titanium-nitride-oxide on the stent surface, based on plasma technology that uses the nano-synthesis of gas and metal. Preclinical in vitro and in vivo investigation confirmed blood compatibility of titanium (nitride-) oxide films. Titanium-nitride-oxide-coated stents demonstrated a better angiographic outcome, compared with bare-metal stents at mid-term follow-up; however, they failed to achieve non-inferiority for angiographic outcome versus second-generation drug-eluting stents. Observational studies showed adequate clinical outcome at mid-term follow-up. Non-randomized studies showed an outcome of titanium-nitride-oxide-coated stents comparable to - or better than - first-generation drug-eluting stents at long-term follow-up. Two randomized controlled trials demonstrated comparable efficacy outcome, and a better safety outcome of titanium-nitride-oxide-coated stents versus drug-eluting stents at long-term follow-up. Evaluation by optical coherence tomography at mid-term follow-up revealed better neointimal strut coverage associated with titanium-nitride-oxide-coated stents versus drug-eluting stents; yet, neointimal hyperplasia thickness was greater. Key messages Stents coated with titanium-nitride-oxide demonstrated biocompatibility in preclinical studies: they inhibit platelet and fibrin deposition, and reduce neointimal growth. In observational and non-randomized studies, titanium-nitride-oxide-coated stents were associated with adequate safety and efficacy outcome. In randomized trials of patients with acute coronary syndrome, titanium-nitride-oxide-coated stents were associated with a better safety outcome, compared with drug-eluting stents; efficacy outcome was comparable.