Comparative assessment of three drug eluting stents with different platforms but with the same biodegradable polymer and the drug based on quantitative coronary angiography and optical coherence tomography at 12-month follow-up

Drug-Eluting Stents: Technical and Clinical Progress

Drug-eluting stents (DES) demonstrated superior efficacy when compared to bare metal stents and plain-old balloon angioplasty and are nowadays used in almost all percutaneous revascularization procedures. The design of the stent platforms is constantly improving to maximize its efficacy and safety. Constant development of DES includes adoption of new materials used for scaffold production, new design types, improved overexpansion abilities, new polymers coating and, finally, improved antiproliferative agents. Especially nowadays, with the immense number of available DES platforms, it is crucial to understand how different aspects of stents impact the effect of their implantation, as subtle differences between various stent platforms could impact the most important issue-clinical outcomes. This review discusses the current status of coronary stents and the impact of stent material, strut design and coating techniques on cardiovascular outcomes.

Association between angiographic and intravascular ultrasound optimizations after new-generation drug-eluting stent implantation and clinical outcomes

BACKGROUND

Uncertainty remains regarding the associations of angiographic optimization and intravascular ultrasound (IVUS) optimization after new-generation drug-eluting stent (DES) implantation.

METHODS

From four randomized trials comparing outcomes between IVUS and angiography-guidance for long or chronic total occlusion (CTO) lesions, 1396 patients who underwent IVUS-guided new-generation DES implantation were enrolled. Of these, 1112 patients (80%) met angiographic optimization criteria (postprocedural diameter stenosis, ≤20%) and were further classified into the matched (same results for angiographic optimization and IVUS optimization) and the mismatched group (opposite results for angiographic optimization and IVUS optimization) according to the meeting of IVUS optimization criteria (minimal stent area, ≥5.5 mm2 or ≥80% of mean reference lumen area). The major adverse clinical events (MACE) were compared.

RESULTS

Of 1112 patients with angiographic optimization, 675 patients met the IVUS optimization criteria (61%; matched), but 437 patients (39%; mismatched) failed to meet IVUS optimization criteria (false-positive rate = 76%). On multivariate analyses, age >60 years, reference vessel diameter ≤2.7 mm, left circumflex artery and lesion length ≥33 mm were significant predictors for the mismatched. When comparing the 12-month MACE rates, the mismatched group (6.8%) showed a significantly higher rate than the matched group (1.5%; hazard ratio = 2.62; 95% confidence interval = 1.20-5.72; P = 0.012), mainly driven by a higher target-vessel revascularization rate (6.4 vs 1.4%; P = 0.021).

CONCLUSION

Despite meeting angiographic optimization criteria in long or CTO lesions, more than one-third of the patients with IVUS-guided new-generation DES implantation failed to meet the IVUS optimization criteria and had worse clinical outcomes. Therefore, IVUS optimization should be considered for patients who had predictors of mismatch.

Effect of Paclitaxel-Coated Balloon Angioplasty on Side Branch Lesion and Cardiovascular Outcomes in Patients with De Novo True Coronary Bifurcation Lesions Undergoing Percutaneous Coronary Intervention

PURPOSE

To compare the effects of paclitaxal-coated balloon (PCB) versus conventional balloon (CB) on side branch (SB) lesion and cardiovascular outcomes in patients with de novo true bifurcation lesions.

METHODS

In total, 219 patients with de novo true bifurcation lesions were enrolled and divided into PCB group (102 cases) and CB group (117 cases) according to angioplasty strategy in SB. Drug-eluting stent (DES) was implanted in main vessel (MV) for each subject. All subjects underwent a 12-month follow-up for late lumen loss (LLL), restenosis, and major adverse cardiovascular events (MACE) after percutaneous coronary intervention (PCI). MACEs included cardiac death, nonfatal myocardial infarction, and unstable angina requiring admission.

RESULTS

There were no differences in diameter, minimum lumen diameter (MLD), and stenosis for bifurcation lesions between the two groups before and immediately after PCI (P > 0.05). After 12-month follow-up, no differences occurred in MV-MLD and MV-LLL between the two groups (P > 0.05); SB-MLD in PCB group was higher than that in CB group (1.97 ± 0.36 mm vs. 1.80 ± 0.43 mm, P = 0.007); SB-LLL in PCB group was lower than that in CB group (0.11 ± 0.18 mm vs. 0.19 ± 0.25 mm, P = 0.024). Multivariate COX analyses indicated that PCB group had lower MACE risk than CB group (HR = 0.480, 95%CI 0.244-0.941, P = 0.033).

CONCLUSION

PCB could decrease SB-LLL and MACE risk in patients with de novo true coronary bifurcation lesion 12 months after single-DES intervention.

Everolimus-Eluting Biodegradable Abluminal Coating Stent versus Durable Conformal Coating Stent: Termination of the Inflammatory Response Associated with Neointimal Healing in a Porcine Coronary Model

Objectives

We evaluated the effect of the different carrier systems on early vascular response through histological analysis and scanning electron microscopy using a porcine model.

Background

Although Synergy™ and Promus PREMIER™ share an identical stent material and drug elution (everolimus), they use different drug carrier systems: biodegradable abluminal coating polymer or durable conformal coating polymer, respectively. However, data regarding the impact of the different coating systems on vessel healing are currently limited.

Methods

Twelve Synergy™ and Promus PREMIER™ were implanted in 12 swine. Histopathological analysis of the stented segments was performed on the 2^nd and 14^th days after implantation. Morphometric analysis of the inflammation and intimal fibrin content was also performed.

Results

On the 2^nd day, neointimal thickness, percentage of neointimal area, and inflammatory and intimal fibrin content scores were not significantly different between the two groups. On the 14^th day, the inflammatory and intimal fibrin content scores were significantly lower in Synergy™ versus those observed in Promus PREMIER™. In Synergy™, smooth muscle cells were found and the neointimal layers were smooth. In contrast, inflammatory cells were observed surrounding the struts of Promus PREMIER™.

Conclusions

These results demonstrate that termination of reactive inflammation is accelerated after abluminal coating stent versus implantation of conformal coating stent.

Comparison of neointimal coverage between ultrathin biodegradable polymer-coated sirolimus-eluting stents and durable polymer-coated everolimus-eluting stents: 6 months optical coherence tomography follow-up from the TAXCO study

Aim

The TAXCO study was designed to compare the degree of neointimal coverage and the prevalence of malapposition at 6 months subsequent to implantation of ultrathin biodegradable polymer‐coated sirolimus‐eluting stents (SES) and durable polymer‐coated everolimus‐eluting stents (EES) of thin strut thickness using optical coherence tomography (OCT).

Methods

The TAXCO study included a total of 42 patients who gave consent and underwent OCT examination between August 2017 and September 2017. Of 42, five patients' OCT examinations were of insufficient quality for quantitative analysis. Thus, the OCT analysis group consisted of 37 patients. Among them, 16 patients were treated with Xience (Abbott Vascular) and 21 with Tetriflex (Sahajanand Medical Technologies Pvt. Ltd., Surat, India), 6 (±1) months earlier at our institution. The OCT was performed using a C7 Dragonfly™ imaging catheter (St. Jude Medical Inc.). All OCT images were analyzed at an independent core laboratory (Cardiovascular Research Center, São Paulo, Brazil) by analysts who were blinded to patient and procedural information.

Results

A total of 763 crosssections (6,882 struts) were analyzed in Xience group, and 1,127 crosssections (9,968 struts) in Tetriflex group. At 6 months, on per‐lesion basis, no significant differences were observed between Xience group and Tetriflex group in mean percentage of uncovered struts (1.87 ± 3.86 vs. 2.42 ± 3.46, p = .137) and malapposed struts (0.05 ± 0.2 vs. 0.21 ± 0.69, p = .302). Strut‐level neointimal thickness also did not differ between Xience group and Tetriflex group (0.18 ± 0.12 vs. 0.14 ± 0.08 mm, p = .286).

Conclusion

This OCT study found no significant difference in strut coverage and neointimal thickness at 6 months after implantation of biodegradable polymer‐coated Tetriflex, when compared with durable polymer‐coated Xience.

Angiographic Restenosis in Coronary Bifurcations Treatment with Regular Drug Eluting Stents and Dedicated Bifurcation Drug-Eluting BiOSS Stents: Analysis Based on Randomized POLBOS I and POLBOS II Studies

Aim

The marked variation in bifurcation anatomy has brought about an ongoing search for stents specifically constructed for coronary bifurcations. This study aimed to analyze the angiographic restenosis prevalence and patterns and predictors of different patterns in dedicated bifurcation BiOSS® vs. current generation drug-eluting stents implanted in coronary bifurcation lesions based on data from two clinical trials POLBOS I and II.

Methods

Dedicated bifurcation BiOSS® stents were compared with drug-eluting stents (DES) in patients with stable coronary artery disease (CAD) or nonST elevation acute coronary syndrome (NSTE-ACS) (POLBOS I: paclitaxel eluting BiOSS® Expert vs. DES; POLBOS II: sirolimus eluting BiOSS® LIM vs. DES). Provisional T-stenting was the default treatment. Morphological pattern of in-stent restenosis according to the modified Mehran classification adopted for bifurcation lesions was assessed with bifurcation dedicated quantitative coronary angiographic software (CAAS 5.11, Pie Medical Imaging BV, the Netherlands).

Results

In total, 445 patients (222 patients in BiOSS group and 223 patients in DES group) were included into the analysis. In BiOSS group 24 cases of angiographic restenosis (10.8%) were recorded, and in DES group-17 cases (7.6%) at 12 months follow-up (angiographic control rate at follow-up-90.3%). In the BiOSS group most frequent medina classification in restenotic cases was 0.0.1 (25%), whereas in DES-0.0.1 and 0.1.1 (23.5% each). In multivariate regression analysis proximal optimization technique was associated with the lowest chance for restenosis (OR 0.15, 95% CI 0.06-0.33), whereas diabetes on insulin was associated with the highest risk of restenosis (OR 4.21, 95% CI 1.48-11.44).

Conclusions

The angiographic restenosis pattern and rate was similar between BiOSS stents and DES in coronary bifurcation lesions.

Recent Advances in Polymeric Implants

Implantable drug delivery systems, such as drug pumps and polymeric drug depots, have emerged as means of providing predetermined drug release profiles at the desired site of action. While initial implants aimed at providing an enduring drug supply, developments in polymer chemistry and pharmaceutical technology and the growing need for refined drug delivery patterns have prompted the design of sophisticated drug delivery implants such as on-demand drug-eluting implants and personalized 3D printed implants. The types of cargo loaded into these implants range from small drug molecules to hormones and even therapeutic cells. This review will shed light upon recent advances in materials and composites used for polymeric implant fabrication, highlight select approaches employed in polymeric implant fabrication, feature medical applications where polymeric implants have a significant impact, and report recent advances made in these areas.