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  3. Non-longitudinal Stent Deformation – Case 1
 Stent Deformation

Non-longitudinal Stent Deformation – Case 1

Clinical Presentation

  • 52-year-old female who presented with chest pain (CCS Class IV).

Past Medical History

  • HTN, HLD, DM, Former Tobacco Use, CAD s/p 1-Vessel CABG and Multiple PCI’s, PAD s/p PTCA, GERD
  • LVEF 60%

Clinical Variables

  • Stress MPI: Mild inferolateral ischemia.

Medications

  • Home Medications: Aspirin, Prasugrel, Atorvastatin, Metoprolol Succinate, Amlodipine, Ranitidine
  • Adjunct Pharmacotherapy: Prasugrel, Heparin IV

Pre-procedure EKG

Angiograms

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Left internal mammary artery (LIMA) to LCx graft angiography
  • no obstruction in the graft.
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Left internal mammary artery (LIMA) to LCx graft angiography

  • no obstruction in the graft.
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Right coronary artery (RCA) angiography

  • no significant disease in the RCA.
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Left coronary artery angiography

  • 70-80% distal left main (LM) lesion
  • 80-90% stenosis in the proximal left anterior descending (LAD) artery.
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Cutting balloon angioplasty of the LM-LAD lesion with a Wolverine 3.5/6mm balloon.

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Angiography of the LM-LAD after cutting balloon angioplasty.

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Positioning of an Xience Sierra 4.0/18mm stent in the LM extending into the proximal LAD.

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Angiography of the LM after stent placement.

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Post-dilatation of the stent in the LM-LAD with a NC Emerge 4.5/8mm balloon.

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Angiography of the LM-LAD after stent post-dilatation.

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Guide catheter was inadvertently disengaged, and wire position was lost. LM was re-engaged with the guide catheter, and the wire was reintroduced.

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Repeat post-dilatation of the LM with a NC emerge 4.5/8mm balloon.

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Angiography of the LM after stent post-dilatation showing stent deformation. When the guide catheter was re-engaged, it was not positioned co-axial, and the wire was re-introduced through a more distal stent strut. As a result, post-dilatation led to stent deformation.

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Guide catheter repositioning and an attempt to place another wire through the true ostium of the LM with the initial wire still in place.

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Difficulty introducing a second wire through the true ostium of the LM. A Supra Cross microcatheter was used to assist with wire introduction and positioning.

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Successful wiring of the true ostium of the LM-LAD with a second wire and use of a Supra Cross microcatheter.

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Positioning of a Trek NC 4.0/12mm balloon to cover the true ostium of the LM.

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Post-dilatation of the true ostium of the LM with a Trek NC 4.0/12mm balloon.

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Post-dilatation of the true ostium of the LM with a NC Emerge 4.5/8mm balloon.

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Angiography of the LM after repeat stent post-dilatation.

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Final angiography showing successful intervention and mending of the deformed stent.

Post-procedure EKG

Case Overview

  • Underwent intervention of the LM.
  • Following successful stent placement and post-dilatation, the guide catheter was inadvertently disengaged and wire position was lost.
  • The LM was re-engaged with the guide catheter and the LM-LAD re-wired. However, the wire was introduced through a distal stent strut.
  • Repeat post-dilatation of the proximal stent edge was performed with follow up angiography showing deformation of the stent.
  • A Supra Cross microcatheter was used to introduce a second wire through the true ostium of the LM.
  • Repeat post dilatation of the stent was performed, successfully mending the deformed stent.
  • Troponin-I peaked at 0.02 ng/mL and CK-MB peaked at 0.5 ng/mL.
  • Patient was discharged home the next day without further sequelae.

Learning Objectives

  • What is the likely explanation or reason why the complication occurred?
    • Introduction of a coronary wire through a distal stent strut followed by post-dilatation of the stent-strut.
  • How could the complication have been prevented?
    • Maintain guide catheter co-axiality, be cautious with manipulation of the guide catheter, and continuously monitor the position of the guide catheter throughout the procedure. This is extremely important when there is difficulty delivering equipment in tortuous, and calcified lesions.
    • Maintaining wire position, especially when dealing with complex interventions.
    • Intra-coronary imaging with (IVUS/OCT) would have allowed for direct visualization of the wire at its entry point.
  • Is there an alternate strategy that could have been used to manage the complication?
    • If a deformed stent fails to be mended with post-dilatation, consider placing another stent.
  • What are the important learning points?
    • This complication could have been avoided with proper handling of the guide catheter. When the LM was re-engaged, the guide catheter was not positioned co-axially and the guidewire was introduced through a distal stent strut instead of the true ostium of the LM. Next, a balloon was passed through the distal stent strut and post dilatation was performed, leading deformation of the stent. It is important to remember, if there is ever doubt of positioning of the guide catheter or guidewire, it is best to remove and reintroduce the equipment prior to performing an intervention.
Educational Content

LONGITUDINAL STENT DEFORMATION

  • Longitudinal stent deformation (LSD) is defined as accidental mechanical distortion or shortening of a stent along its longitudinal axis following stent deployment
  • Incidence - 0.2% in contemporary era1
  • Risk factors:1
    • Calcification
    • Ostial disease
    • Bifurcation disease
    • Use of guide extension catheters
    • Balloon post-dilatation
    • Greater number of deployed stents
  • Most common cause:1 Guide catheter or device (e.g. sharp tipped balloon or IVUS catheter) abutting on proximal stent edge, or poorly deflated or winged balloon or other device catching a mid or distal strut upon withdrawal.
  • New-generation (cobalt-chromium or platinum-chromium) stents with thinner struts and less connectors allow successful navigation in complex lesions and make side branch access easier. However, with the reduction of the number of fixed links between cells and the alteration of their geometry partly sacrifices their longitudinal strength, leading to an increased risk LSD.2

Longitudinal stent deformation: under fluoroscopy (stent compression) and IVUS imaging showing overlapping and distorted struts (concertina pattern)

  • LSD can manifest as longitudinal stent compression, which is seen on fluoroscopy as a dark band in the region of compression also called stent accordion, concertina or wrinkling or it can manifest as longitudinal stent elongation which appears like a fracture in the stent (pseudo-fracture).
  • The Promus Element stent has been the most frequently reported DES that is vulnerable to LSD, mainly because of its weakness against longitudinal forces, which may be explained by its thin strut and offset peak-to-peak design.2 However, LSD has been reported with other DES, suggesting that risk factors outside of stent platform design may have a role in LSD.2
  • LSD while rare, is under-recognized, and may result in:1
    • Areas of stent overlap, distortion, malapposition and arterial injury
    • Target lesion injury with lack of stent coverage
    • Increased risk of stent thrombosis, restenosis and emergent CABG
  • Prevention
    • Operator must pay attention during PCI of ostial lesions involving deep intubation with guiding catheters or extension systems through already stented segment
    • If resistance to passage of a secondary device in the stent do not push hard
    • Use caution following deliberate under expansion of the proximal portion of a very long stent in a tapered vessel as further delivery of additional devices can lead to LSD
  • Treatment
    • When LSD is suspected, radiographic assessment of the stented segment, preferably with StentBoost (Philips, Andover, Massachusetts) or an equivalent image-enhancement program, should be done
    • Confirm wire position and use a small compliant balloon followed by a high-pressure noncompliant balloon aiming to ensure adequate expansion of deformed stent struts and their apposition to coronary arterial
    • If LSD still persists, another stent can be used
    • IVUS or optical coherence tomography use is strongly encouraged, although it is advisable to proceed to intracoronary imaging once LSD has been treated to avoid further potential deformation


References

  1. Kereiakes D.J., Popma J.J., Cannon L.A., et al. (2012) Longitudinal stent deformation: Quantitative coronary angiographic analysis from the PERSEUS and PLATINUM randomised controlled clinical trials. EuroIntervention 8:187–195.
  2. Ormiston J.A., Webber B., Webster M.W.I. (2011) Stent longitudinal integrity - bench insights into a clinical problem. J Am Coll Cardiol Intv 4:1310–1317.

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