Longitudinal Deformation of Contemporary Coronary Stents: An Integrated Analysis of Clinical Experience and Observations from the Bench

Objective: To report clinical experience with longitudinal stent deformation (LSD) and observations from the bench. Background: LSD was recently reported with thin‐strut coronary stents. Whether it is related to a particular stent or constitutes a class‐effect remains debatable. Methods: After 2 cases of LSD were reported, information was sent to operators to warn of this event and identify possible cases. All cases were reviewed to ensure LSD had occurred. Simultaneously, bench testing was conducted to identify the susceptibility of stents to longitudinal compression and whether LSD detection is influenced by fluoroscopic stent visibility. Results: Between July 2010 and November 2011, 2,705 coronary interventions were performed with 4,588 stents (Promus Element = 41.6%, Xience Prime = 24.4%). Six patients with LSD were identified, all with Promus Element (0.31%). Wire bias was a predisposing factor in 4 cases. All patients were treated with postdilatation and/or additional stenting. No adverse events occurred (mean 5.8 months). In bench testing, LSD occured in all examined stents, but at different levels of applied force (weight). Most shortening at 50 g was observed with Promus Element (38.9%), as was the best visibility of LSD on x‐ray images. With postdilatation all stents showed some re‐elongation. Conclusion: In our practice LSD was a rare observation only seen with the Promus Element stent. When subjected to longitudinal compression in a bench test all contemporary stents can be compressed. Compression of Promus Element occurs at a lower force, but it is the only stent where deformations are detected with x ray. Postdilatation can partially improve LSD. (J Interven Cardiol 2012;25:576–585)     

Clinical and angiographic outcomes of axial stent deformations in unrestricted real world patient population

Background

Prior reports have suggested that the design of the Promus Element stent is prone to longitudinal stent deformation (LSD). However, little is known about the clinical and angiographic outcomes of Promus Element stent axial deformations when implanted in unrestricted coronary lesions.

Method and Results

Two independent reviewers retrospectively evaluated the procedure steps of 961 Promus Element stent (833 de novo lesions in 494 consecutive patients) implanted in unrestricted coronary lesions, between February 2012 and March 2013, and compared the prevalence, predictors, and the mid‐term clinical and angiographic outcomes between lesions with and without stent deformation. Fifteen stents (1.56%) with LSD were observed (95% confidence interval [CI]: 0.78–2.34%). The proximal edge of the stent was deformed in 13 stents (86.6%). Ostial stenting (Adjusted Odds ratio [OR]: 9; 95%CI: 2.27–33.3; P = 0.002), and bifurcation lesions (Adjusted OR: 3; 95%CI: 1.03–8.8; P = 0.04) were independently associated with the occurrence of stent deformation. LSD led to unplanned stenting in (53%, 8 of 15) of the deformed stents, which consumed larger contrast volume and longer fluoroscopy time. At 8‐month follow‐up, there was no significant difference in binary restenosis rate and target lesions revascularization between both groups (P = 0.98, and P = 0.56, respectively), while death occurred in six patients of the non‐LSD group (1.36%, 6 of 440) and none in the LSD group. All patients of the LSD group had no major adverse clinical events at 8‐month follow‐up.

Conclusions

Axial stent deformation in Promus Element platform is an infrequent event, occurs following manipulation of the interventional tools. Other than unplanned stenting, the LSD was not associated with any adverse clinical events at 8‐month follow‐up.

     

Occurrence of longitudinal stent compression before stent deployment: Two case studies

Several recent reports have described the occurrence of longitudinal stent deformation(LSD, defined as the distortion or shortening of a stent along the longitudinal axis), following its successful deployment. However, few reports have described LSD prior to any stent deployment. This previously unrecognized complication is the result of modifications to stent design. It has been noted that the new-generation stent platforms have a reduced number of connectors, which in turn causes a reduction in longitudinal stent strength. To corroborate previous findings by our lab and others(Vijayvergiya et al, 2013), we describe here two cases of LSD prior to stent deployment that occurred due to crushing of the proximal stent edge by the guide catheter while attempting to withdraw the crimped stent. In addition, we discuss the associated risk factors, such as the length of the stent, and specific management strategies, including technical guidelines and use of fluoroscopic guidance for maneuvering the stent during the procedure.     

Occurrence of longitudinal stent compression before stent deployment: Twocase studies简

Several recent reports have described the occurrence of longitudinal stent deformation (LSD, defined as the distortion or shortening of a stent along the longitudinal axis), following its successful deployment. However, few reports have described LSD prior to any stent deployment. This previously unrecognized complication is the result of modifications to stent design. It has been noted that the new-generation stent platforms have a reduced number of connectors, which in turn causes a reduction in longitudinal stent strength. To corroborate previous findings by our lab and others (Vijayvergiya et al, 2013), we describe here two cases of LSD prior to stent deployment that occurred due to crushing of the proximal stent edge by the guide catheter while attempting to withdraw the crimped stent. In addition, we discuss the associated risk factors, such as the length of the stent, and specific management strategies, including technical guidelines and use of fluoroscopic guidance for maneuvering the stent during the procedure.     

In early returns scoring scores big

• A scoring or cutting balloon is always useful in preventing slippage during therapy of in‐stent restenosis.
• A drug‐coated scoring balloon for in‐stent restenosis may be an alternative to a drug‐coated balloon
• Definitive comparison trials are needed and likely to help define their exact role in patients with in‐stent restenosis

     

Early stent thrombosis: Nearly gone,but never forgotten

• Early stent thrombosis occurs in ～1% of patients treated with primary PCI and increases shock, stroke, and mortality.
• Early stent thrombosis was associated with small stent diameter, failure to use glycoprotein inhibitors, and bivalirudin use.
• Minimizing stent thrombosis may require the use of imaging and aggressive antithrombotic therapy

     

Percutaneous pulmonary valve implantation: It's not like the aortic valve

• Children with branch pulmonary artery stenosis represent a challenging cohort for stenting
• Premounted stent implantation provides immediate obstruction relief and hemodynamic improvement in infants
• Planned stent intervention is required to account for somatic growth and next stage palliation in children
• Continued slenderization of adult coronary and peripheral interventions, stent technology, and delivery systems may allow for more durable solutions in light of patient size

     

Another tool for the fork‐in‐the‐road toolbox

• A provisional stent strategy for bifurcation disease is a good rule of thumb.
• The Tryton bifurcation stent is an additional potential useful tool for use in complex coronary disease.
• If and when this device has a drug‐eluting side branch, its true role may be clearer.

     

Treating on the edge

• Treatment of stent graft edge restenosis can be successfully treated but optimal treatment has not been identified.
• The practice of continued duplex surveillance for stent grafts appears to be important.
• Randomized trials comparing drug technology and to properly sized stent graft extension will be needed.

     

Expanding the armamentarium for the treatment of left main disease

• The BiOSS LIM stent is a dedicated device for the treatment of bifurcation lesions that present a proximal and distal part with two different diameters and a middle zone with two connecting struts facilitating side branch rewiring.
• In this study, after implanting the BiOSS LIM stent in the left main, rewiring to the side branch was easier compared to standard metallic stent.
• The device may be very useful in the treatment of bifurcation lesions for provisional stenting strategies or for two‐stent strategies such as T‐stenting or T‐and‐Protruding (TAP).

     

All stent strut malappositions are not created equal

• The current meta‐analysis evaluates the relationship of late incomplete stent apposition (LISA) observed either by IVUS or OCT 6–18 months after PCI and long‐term outcomes, particularly in regard to stent thrombosis (ST) and has demonstrated a small but significant increase in ST with LISA.
• The results of the current study do not apply to acute stent malapposition whose relevance to adverse outcomes is uncertain based on current evidence and a malapposition classification based on presence, length, and severity of malapposed struts.
• A classification of stent malapposition based on cause of malapposition is proposed as a method to determine prognostic importance of acute incomplete stent apposition.

     

Embolic protection device use and its association with procedural safety and long‐term outcomes following saphenous vein graft intervention: An analysis from the British Columbia Cardiac registry

• Coronary stents are commonly deployed using high pressure. However, the duration time of balloon inflation during deployment is still to be determined.
• Vallurupalli and coworkers, in this issue of CCI, show that the stent system takes an average of 33 sec to “accommodate” its pressure during in vitro deployment. In patients, the mean stent inflation time to achieve pressure stability was 104 seconds, ranging from 30 to 380 sec.
• These results challenge a rapid inflation/deflation approach for stent deployment. It is suggested that the duration of the inflation might be individualized, in a case‐by‐case approach.
• However, the findings must be interpreted with caution, as they cannot be directly extrapolated to more diverse clinical, angiographic, and interventional scenarios.

     

Aorto‐Ostial Lesions: Battling an Old Foe

• Aorto‐ostial lesions (AOLs) entail several diagnostic and treatment challenges.
• The Flash Ostial System enables flaring of the overhanging stent, optimizing stent deployment in AOLs.
• Careful planning is essential to achieve optimal stent implantation and avoid early and late complications during the treatment of AOLs.

     

Advances in the treatment of coronary perforations

• Coronary artery perforation is an infrequent, but potentially life‐threatening complication of percutaneous coronary intervention. There are four types of coronary perforation: (a) large vessel; (b) distal vessel; (c) septal collateral; and (d) epicardial collateral perforation.
• Implantation of a covered stent is the cornerstone of large vessel perforation treatment and can be used in some distal vessel perforations, when embolization is not feasible. Until now the only available covered stent in the US was the Graftmaster stent (two bare metal stents with a PTFE membrane in‐between them), that has high profile and is challenging to deliver and expand. Use of the Graftmaster has been associated with high rates of in‐stent restenosis and stent thrombosis.
• Availability of more deliverable covered stents, such as the BeGraft (Bentley InnoMed GmbH, Hechingen, Germany) and PK Papyrus (BIotronik, Lake Oswego, Oregon, that recently received FDA approval) will greatly facilitate treatment of large vessel coronary perforations.

     

Statin attenuation of stent inflammatory response

• Stenting induces inflammation
• Inflammation mediates endothelialization, but may contribute to in‐stent restenosis
• Immunomodulatory effects of statins reduce post stent inflammation

     

Intravascular lithotripsy for stent under-expansion: Panacea or Pandora's box?

• Balloon undilatable lesions are common and can be challenging to treat, especially within stents, and require a systematic, algorithmic approach.
• Stent under-expansion is usually treated with high-pressure balloon inflations, followed by plaque modification balloons, laser with contrast, orbital or rotational atherectomy, and subintimal crossing with coronary artery bypass graft being the ultimate solution is all techniques fail to expand the stent.
• Intravascular Lithotripsy (IVL) appears to be an easy to use and effective tool for treating stent under-expansion, but further study is needed to confirm its efficacy and (acute and long-term) safety.

     

Back to nature: A more natural alternative to the PTFE covered stent: Twenty‐two years in the making

• The introduction of easily deployed covered stents has made PCI safer.
• The homemade venous and PTFE covered stent were effective but not practical for sealing perforations.
• The novel pericardial covered stent graft goes back to a more natural covering and is more easily deployed.

     

Panta rhei,also drug eluting stent technology

• The Resolute zotarolimus eluting stent (ZES) is a next‐generation durable polymer, thin‐struts drug eluting stent. Although several randomized and observational studies have proven its safety and efficacy, long‐term follow‐up data are still limited.
• This prospective, multicenter, single arm study, showed favorable 5‐year outcomes in patients undergoing Resolute ZES implantation, with considerably low rate of repeated revascularization and stent thrombosis.
• Data on long‐term performance of next‐generation drug eluting stents are of paramount importance to adequately inform decision‐making in contemporary clinical practice.

     

Leave nothing behind: Promising results for coronary drug‐coated balloons in clinical practice

• 1,025 patients with de novo coronary artery disease (66.9%) or in‐stent restenosis (ISR) (33.1%) underwent treatment with paclitaxel drug‐coated balloons in a multinational single‐arm registry. Bail‐out stenting rate was only 4.8%.
• One‐year target lesion revascularization was 2.3% for de novo lesions, 2.9% for bare metal stent ISR, and 5.8% for drug‐eluting stent ISR.
• Short‐term results with coronary drug‐coated balloons are promising. Nonetheless, long‐term data, preferably from randomized trials are necessary to confirm their safety and efficacy.

     

Overlapping bio‐absorbable scaffolds: Aim for D2D technique?

• The results of overlapping metallic stents have been concerning but this practice is often unavoidable in the setting of long or tortuous lesions, diameter discrepancy of proximal and distal vessel, and for residual dissections.
• Theoretically, bio‐absorbable scaffolds may carry an advantage over metallic stents due to the progressive resorption of the scaffold theoretically rendering the overlap a non‐issue; this has not been clinically evident.
• Since stent/scaffold overlap cannot be entirely avoided, improved stent delivery/deployment and scaffold design modification may reduce complications in this complex patient subset.