Incidence and mechanisms of longitudinal stent deformation associated with Biomatrix, Resolute, Element, and Xience stents: Angiographic and case-by-case review of 1,800 PCIs

Unintended Deformation of Stents During Bifurcation PCI: An OCTOBER Trial Substudy

BACKGROUND

Unintended deformation of implanted coronary stents can lead to loss of coronary access, stent thrombosis and coronary events during follow-up. The incidence, mechanisms and clinical outcomes of unintended stent deformations (USD) during complex bifurcation stenting are not well characterized.

OBJECTIVES

In a prespecified analysis of the OCTOBER (European Trial on Optical Coherence Tomography Optimized Bifurcation Event Reduction) trial, we aimed to: 1) determine the incidence and characterize mechanisms of USD identified by optical coherence tomography (OCT); and 2) evaluate physician's detection and correction of accidental abluminal rewiring and USD.

METHODS

OCT scans were analyzed for accidental abluminal rewiring and USD. When USD was identified, the plausible mechanism was determined by analysis of all procedural OCT scans and the corresponding angiograms.

RESULTS

USD was identified by the core lab in 9.3% (55/589) of OCT-guided cases. Accidental abluminal rewiring was the cause in 44% (24/55), and guide catheter collision was the cause in 40% (22/55) of cases. USD was found in 18.5% of all cases with left main bifurcation percutaneous coronary intervention. The total incidence of abluminal rewiring was 33 in 32 OCT-guided cases (5.4%) and was corrected by physicians in 18 of 33 appearances (54.5%). The 2-year major adverse cardiac event rate for patients with untreated USD (n = 30) was 23.3%, whereas patients with confirmed or possibly corrected USD (n = 25) had no events during follow-up.

CONCLUSIONS

USD was associated with adverse procedural complications and cardiac events during follow-up when not identified and corrected. The predominant mechanisms were undetected abluminal rewiring and guide catheter collision. Left main bifurcation percutaneous coronary intervention was a particular risk with USD detected in 18.5% of cases.

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.

Guide catheter extension systems: Hype or a need?

Guide catheter extension system (GCES) is a valuable tool for interventional cardiologists, especially in complex cases. GCES increases guide back-up support and is crucial in complex PCI procedures, particularly in cases of severe calcification and tortuosity. Apart from their primary use to increase back-up support of guide by providing coaxial alignment, deep intubation and facilitation of stent delivery, GCES are now being increasingly used in different clinical indications including complex and high-risk coronary intervention interventions.

Comparison of the Physical Characteristics of Support Stents for Cerebral Aneurysm Embolization

Objective

There is a limited understanding of the characteristics of individual intracranial stents used for aneurysm treatment. We used an experimental model to evaluate the physical characteristics of support stents for aneurysm embolization.

Methods

Enterprise 2 VRD 4.0 × 39 mm, Neuroform Atlas 4.5 × 21 mm, and LVIS 4.5 × 32 mm stents were: 1) observed under light microscopy and subjected to measurements of 2) circumferential radial force, 3) strut tension, 4) stent compression, and 5) conformability upon bending.

Results

1) Light microscopy showed a large structural difference between laser-cut (Enterprise 2 VRD, Neuroform Atlas) and braided (LVIS) stents. 2) Within the range of indicated blood vessel diameters, the radial force of Enterprise 2 VRD was higher than that of Neuroform Atlas. An extremely large force was required to decrease the LVIS diameter. 3) Neuroform Atlas easily deformed compared to Enterprise 2 VRD, while LVIS was extended with a smaller traction force than that required for Neuroform Atlas. 4) The compression strength was in the order of Enterprise 2 VRD >Neuroform Atlas >LVIS. 5) Enterprise 2 VRD showed a decreased cell area on the concave side, and Neuroform Atlas showed deformation with overlapping struts on the concave side. LVIS naturally adhered to the wall of the blood vessel model.

Conclusion

Laser-cut and braided stents showed different physical characteristics that were visualized and shown as numerical data. These findings improve the understanding of the proper use of these stents in clinical applications.

A Practical Approach to the Management of Complications During Percutaneous Coronary Intervention

Percutaneous coronary intervention relieves symptoms in patients with chronic ischemic heart disease resistant to optimal medical therapy and alters the natural history of acute coronary syndromes. However, adverse procedural outcomes may occur during the intervention. Knowledge of possible complications and their timely management are essential for the practicing cardiologist and can be life-saving for the patient. In this review, the authors summarize potential complications of percutaneous coronary intervention focusing on their practical management.

Outcomes of patients treated with durable polymer platinum-chromium everolimus-eluting stents: a meta-analysis of randomised trials

AIMS

The durable polymer platinum-chromium everolimus-eluting stent (PtCr-EES) is a new-generation drug-eluting stent (DES) with a platinum-enriched metallic platform developed to improve the percutaneous treatment of patients with coronary artery disease. We sought to investigate the performance of durable polymer PtCr-EES versus other new-generation DES.

METHODS AND RESULTS

We undertook a meta-analysis of trials in which patients receiving percutaneous coronary intervention (PCI) were randomly assigned to durable polymer PtCr-EES versus other new-generation DES (other DES). Primary efficacy and safety outcomes were target lesion revascularisation (TLR) and definite/probable stent thrombosis (ST), respectively. Secondary outcomes were myocardial infarction (MI), target vessel revascularisation (TVR), death, cardiac death and longitudinal stent deformation (LSD). A total of 11,036 patients in seven trials received a PCI with either durable polymer PtCr-EES (n=6,613) or other DES (n=4,423). This latter group comprised patients treated with biolimus- (n=325), cobalt-chromium everolimus- (n=1,940) or zotarolimus-eluting stents (n=2,158). After a median follow-up of 12 months (interquartile range 12-24), durable polymer PtCr-EES displayed a risk of TLR (odds ratio 0.98, 95% confidence interval [CI]: 0.75-1.29; p=0.90) and definite/probable ST (0.89 [0.55-1.45]; p=0.63) comparable to that of other DES. However, the durable polymer PtCr-EES was associated with a higher risk of LSD (12.05 [1.60-90.71], p=0.02) compared to other DES. There was no significant difference with regard to other secondary outcomes nor was there heterogeneity across trials.

CONCLUSIONS

At one-year follow-up, the durable polymer PtCr-EES displays a performance comparable to that of other new-generation DES platforms.

The potential hazard of a non-slip element balloon causing distal longitudinal stent deformation: the first clinical experience and in vitro assessment

BACKGROUND

A new complication, longitudinal stent deformation (LSD), is increasingly reported with recent intracoronary stent designs. There have been experiences of unusual cases of distal LSD caused by entrapment of a Lacrosse® non-slip element (NSE) balloon (Goodman Co., Ltd., Nagoya, Japan), which has three flexible nylon elements to prevent slippage. Accordingly, the aim of this study is to report the clinical experience of distal LSD caused by the NSE in the documented center and to investigate the incidence and mechanisms involved.

METHODS

Coronary intervention cases were retrospectively reviewed using the NSE balloon in hospital between May 2014 and June 2017. In bench testing, distal LSD was reproduced in a silicon tube model to identify its mechanism.

RESULTS

A total of 95 patients with 107 lesions underwent coronary interventions with NSE. Of these, 72 lesions (12 de-novo lesions and 60 in-stent restenosis) were treated using in-stent dilatation. Two distal LSD cases occurred, representing an incidence of 2.78% (2/72) among all procedures; 16.7% (2/12) of the de-novo lesions developed LSD. In vitro experimentation allowed indentification of the mechanisms involved and bailout strategies.

CONCLUSIONS

This is the first study to evaluate NSE balloon catheter entrapment complicated by distal LSD in which reconstruction of the deformed stent and retrieval of the NSE could be achieved successfully. There is a potential hazard for distal LSD during post-dilatation using the NSE balloon due to its structural characteristics. Careful assessment is needed to prevent this complication.

Longitudinal deformation bench testing using a coronary artery model: a new standard?

Objectives

To compare susceptibility of five different stent platforms with longitudinal stent deformation (LSD) using a clinically relevant bench testing model simulating both short and long malapposed lengths.

Background

Recent data suggest that design modifications to the Promus Element stent which led to the Promus Premier stent has reduced susceptibility to LSD. However, susceptibility to LSD at long malapposed lengths has not been tested. Furthermore, the mechanisms behind susceptibility to LSD are as yet unclear.

Methods

The Omega, Integrity, Multilink 8, Biomatrixand Promus Premier stent platforms were tested. The Omega, Integrity and Multilink 8 platforms were used in place of their drug-eluting equivalents. 3.5 mm stents were deployed in a stepped tube with the distal portion fixed and the proximal test section exposed. The force required to compress stents by a fixed distance at different exposed lengths was compared. Symmetrical and point loading were used.

Results

The Promus Premier was longitudinally as strong as Multilink and Integrity at a short exposed length (4 mm) but weaker, in between Omega and the other platforms, at longer exposed lengths (12 mm). As previously noted, the Omega (Promus Element) platform was significantly weaker than the other stents and Biomatrix was the strongest stent.

Conclusion

Susceptibility to LSD varies depending on length of malapposed segment when tested using a clinically relevant model as in this study. The mechanisms behind the susceptibility are likely multifactorial, including connector number, strut thickness, connector alignment and ring orientation but remain to be elucidated.

Twelve-month results of a prospective, multicentre trial to assess the everolimus-eluting coronary stent system (PROMUS Element): the PLATINUM PLUS all-comers randomised trial

AIMS

The aim of the study was to compare the safety and efficacy of the platinum-chromium-based everolimus-eluting stent (EES) with a cobalt-chromium EES.

METHODS AND RESULTS

We performed a prospective, multicentre, single-blind non-inferiority all-comers study randomising patients with stable or unstable coronary artery disease (2:1) to treatment with the platinum-chromium EES (n=1,952) or the control cobalt-chromium EES (n=1,028) in Europe (PLATINUM PLUS trial). The primary endpoint was target vessel failure (TVF) at 12 months, a composite of target vessel-related cardiac death, myocardial infarction (MI), and ischaemia-driven target vessel revascularisation (TVR). Among 2,980 patients, 33% presented with acute coronary syndromes, and 48% with multivessel disease. At 12 months, the intention-to-treat analysis determined that the platinum-chromium EES was non-inferior to the cobalt-chromium EES for the primary endpoint (86 [4.6%] patients vs. 32 [3.2%], absolute difference 1.4%, 95% confidence interval [CI]: -0.1-2.9; upper limit of the one-sided 95% CI: 2.57%; non-inferiority p=0.012; superiority analysis: hazard ratio [HR] 1.44, 95% CI: 0.96-2.16, p=0.08). In the per protocol analysis, however, the primary endpoint was significantly more common in the platinum-chromium EES (HR 1.64, 95% CI: 1.05-2.55, p=0.03). There were no significant differences in the rates of cardiac death (1.1% vs. 1.0%, p=0.78), MI (1.6% vs. 0.8%, p=0.09), or ischaemia-driven TLR (2.0% vs. 1.6%, p=0.49). The rates of ARC definite or probable stent thrombosis were comparable between platforms (0.8% vs. 0.5%, p=0.44).

CONCLUSIONS

At one year, the platinum-chromium EES satisfied the pre-specified criteria for non-inferiority relative to the control cobalt-chromium EES in this all-comers trial.

Clinical, angiographic and procedural characteristics of longitudinal stent deformation

Recently, longitudinal stent deformation (LSD) has been reported increasingly. Even though the reported cases included almost all stent designs, most cases were seen in the Element™ stent design (Boston Scientific, Natick, MA, USA). It is considered that stent design, lesion and procedural characteristics play a role in the etiology of LSD. Yet, the effect of LSD on long-term clinical outcomes has not been studied well. Element stents implanted between January 2013 and April 2015 in our hospital were examined retrospectively. Patients were grouped into two according to the presence of LSD, and their clinical, lesion and procedural characteristics were studied. Twenty-four LSD's were detected in 1812 Element stents deployed in 1314 patients (1.83 % of PCI cases and 1.32 % of all Element stents). LMCA lesions (16.7 % vs 1.6 %, p < 0.001), complex lesions (75 % vs 35.1 %, p < 0.001), bifurcation lesions (37.5 % vs 18.3 %, p = 0.017), ostial lesions (33.3 % vs 12.8 %, p = 0.003), using of extra-support guiding catheter (54.2 % vs 22.3 %, p < 0.001) and extra-support guidewire (37.5 % vs 16.2 %, p = 0.005) were found to be more frequent in cases with LSD than in cases without it. In addition, the number of stents, stent inflation pressure and the use of post-dilatation were significantly different between the two groups. Two patients had an adverse event during the follow-up period. LSD is a rarely encountered complication, and is more common in complex lesions such as ostial, bifurcation and LMCA lesions. The use of extra-support guiding catheter, extra-support guidewires and low stent inflation pressure increases the occurrence of LSD. Nevertheless, with increased awareness of LSD and proper treatment, unwanted long-term outcomes can be successfully prevented.

Stent fracture and longitudinal compression detected on coronary CT angiography in the first- and new-generation drug-eluting stents

To evaluated prevalence and clinical implication of stent fracture and longitudinal compression in first- and new-generation drug-eluting stents (DES) using coronary computed tomography angiography (CCTA). The incidence of stent fracture and longitudinal compression were compared between first- and new-generation DES in 374 patients who underwent coronary stenting using DES and follow-up CCTA due to recurrent angina. 235 and 139 patients received 322 first- and 213 new-generation DES, respectively. The crude per-stent incidence of longitudinal compression (6.1 vs. 0.3 %, p < 0.001) was higher after new- than first-generation DES implantation using CCTA and the incidence of stent fracture (11.3 vs. 8.1 %, p = 0.23) was comparable. On follow-up coronary angiography for 347 stents, stent fracture (3.2 %) and longitudinal compression (0.9 %) were less detected than those on CCTA. Ostial stenting was a risk factor of longitudinal compression (p < 0.001). Stent fracture was associated with younger patients (p = 0.03), longer stent (p = 0.010), and excessively tortuous lesions (p = 0.001). The presence of stent fracture or longitudinal compression was not associated with poor clinical outcomes. The longitudinal compression more frequently occurred after new-generation DES implantation. The stent fracture was comparable between two DES. However, the occurrence of such mechanical deformities did not translate into a poor clinical outcome.

Clinical utility of platinum chromium bare-metal stents in coronary heart disease

Coronary stents represent a key development for the treatment of obstructive coronary artery disease since the introduction of percutaneous coronary intervention. While drug-eluting stents gained wide acceptance in contemporary percutaneous coronary intervention practice, further developments in bare-metal stents remain crucial for patients who are not candidates for drug-eluting stents, or to improve metallic platforms for drug elution. Initially, stent platforms used biologically inert stainless steel, restricting stent performance due to limitations in flexibility and strut thickness. Later, cobalt chromium stent alloys outperformed steel as the material of choice for stents, allowing latest generation stents to be designed with significantly thinner struts, while maintaining corrosion resistance and radial strength. Most recently, the introduction of the platinum chromium alloy refined stent architecture with thin struts, high radial strength, conformability, and improved radiopacity. This review will provide an overview of the novel platinum chromium bare-metal stent platforms available for coronary intervention. Mechanical properties, clinical utility, and device limitations will be summarized and put into perspective.