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Longitudinal Stent Deformation – Case 1

Clinical Presentation

  • 68-year-old male who presented with chest pain (CCS Class III).

Past Medical History

  • HLD, Former Tobacco Use, CAD s/p Multiple PCI’s, AICD, Anxiety, Depression, Homocysteinemia, IBS, Hypothyroidism
  • LVEF <15%

Clinical Variables

  • Stress MPI: Severe extensive apical and anterior scarring and moderate inferior scarring without significant viability in these segments; mild lateral reversible perfusion abnormality consistent with viability in this segment.

Medications

  • Home Medications: Aspirin, Atorvastatin, Metoprolol Succinate, Ranolazine, Captopril, Spironolactone, Digoxin, Famotidine, Levothyroxine, Sertraline
  • Adjunct Pharmacotherapy: Clopidogrel, Ticagrelor, Bivalirudin

Pre-procedure EKG

Angiograms

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Right coronary artery (RCA) angiography
  • no significant stenoses in the RCA.
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Right coronary artery (RCA) angiography

  • no significant stenoses in the RCA.
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Left coronary artery (LCA) angiography

  • 70-80% distal left main (LM) calcified stenosis
  • 80-90% in-stent restenosis in the proximal left anterior descending (LAD)
  • 70-80% calcified ostial lesion in the left circumflex (LCx).
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LCA angiography

  • 80-90% in-stent restenosis in the proximal left anterior descending (LAD)
  • 50-60% calcified lesion in the mid LAD and 60-70% stenosis in the first diagonal branch (D1).
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Orbital atherectomy of the LM extending into the proximal LCx using a 1.25mm burr at 80k RPM.

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Angiography of the LCA after orbital atherectomy.

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Pre-dilatation of the LM extending into the LCx with a Trek NC 4.0/12mm balloon.

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Pre-dilatation of the LM extending into the LAD with a Trek NC 4.0/12mm balloon.

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Angiography of the LCA after pre-dilatation of the LM-LAD and LM-LCx.

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Deployment of a Promus Premier 4.0/28mm stent in the LM extending into the proximal LCx.

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Deployment of a Promus Premier 4.0/28mm stent in the LM extending into the proximal LAD.

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Post-dilatation of the stent placed in the LM extending into the proximal LCx with a NC Quantum Apex 4.5/12mm balloon.

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Kissing balloon inflation (KBI) of the stents placed in LM-proximal LAD (NC Quantum Apex 4.0/15mm balloon) and LM-proximal LCx (NC Quantum Apex 4.5/12mm balloon).

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Angiography of the LM trifurcation after KBI.

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Post-dilatation of the stent in the proximal LCx using a NC Quantum Apex 4.5/12mm balloon.

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Post-dilatation of the stent in the proximal LAD using a NC Quantum Apex 4.5/15mm balloon.

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Angiography of the LCA after post-dilation of the stents, concerning for longitudinal stent deformation (LSD) of the proximal segments of both stents.

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Positioning of an Xience Alpine 4.0/12mm stent in the LM to cover the LSD segment of the previously placed stents.

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Angiography after placement of a stent in the proximal LM.

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KBI of the stent placed in LM-proximal LAD (NC Quantum Apex 4.0/15mm balloon) and LM-proximal LCx (NC Quantum Apex 4.5/12mm balloon).

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Final angiography showing successful intervention of the LM-LAD and LM-LCx and successful treatment of the LSD.

Post-procedure EKG

Case Overview

  • Underwent intervention of the LM-proximal LAD and LM-proximal LCx with the procedure being complicated by longitudinal stent deformation.
  • An additional stent was placed in the LM to cover the LSD segment of the previously placed stents.
  • Troponin-I peaked at 1.48 ng/mL and CK-MB peaked at 9.9 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?
    • LSD due to aggressive post-dilatation.
  • How could the complication have been prevented?
    • Adequate plaque modification of a calcified lesion prior to stent placement.
    • Careful handling and manipulation of the guide catheter, especially when performing proximal vessel stenting.
    • Minimize guidewire deviation away from the lumen center.
    • Appropriate stent selection.
    • Achieve optimal stent apposition.
    • Implantation of the distal stent first for overlapping stent placement.
    • Careful passage of secondary equipment/catheters across a stented segment to minimize resistance.
    • Sufficient inflation and withdrawal time of post-dilation balloon catheters, especially those with large diameter.
  • Is there an alternate strategy that could have been used to manage the complication?
    • Management of LSD includes:
      • LSD can be diagnosed using fluoroscopy, but imaging with IVUS or OCT is recommended.
      • Perform cautious post-dilatation of the deformed segment of a stent using an appropriate sized (one to one) non-compliant balloon and inflate it gradually. If there is resistance when delivering the balloon use a smaller sized balloon. Placement of another stent may be required to achieve optimal results. Stent should cover as much area of deformation as possible. If unacceptable result or unable to repair the damaged stent, patient may require surgical revascularization.
    • What are the important learning points?
      • Longitudinal stent deformation is characterized by mechanical distortion or shortening of a stent in the longitudinal axis, and can lead to stent thrombosis and restenosis.
      • LSD is a rare and infrequent complication of coronary interventions and it was brought to light after introduction of the Promus Element stent. This stent had thinner struts and was missing a connector between the proximal rings creating a offset peak-to-peak design, which made it weaker against longitudinal forces, and in turn more vulnerable to LSD. Additionally, its high radio-opacity made it easier to detect LSD.
      • It is important to note that LSD can occur with any stent. Newer generation drug eluting stents have thinner struts, improving their deliverability, conformability, flexibility and radial strength. Conversely, this comes at the cost of reduced longitudinal strength making these stents more susceptible to LSD.
      • In addition to stent design, lesion location and complexity, mechanical effect and impact of a guide catheter tip on the proximal portion of the stent, or following passage of secondary devices across a freshly placed stent (i.e post-dilatation balloons, guidewires, filters, microcatheters, extension catheters, imaging catheters, and atherectomy devices) are all related with LSD.
      • Longitudinal stent deformation becomes particularly problematic in cases of complex disease (ostial disease, bifurcation disease, calcification and tortuosity). However, minor stent deformations are expected as a routine part of many two-stent bifurcation procedures and patients generally do well with good angiographic results.
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 era18
  • Risk factors:18
    • Calcification
    • Ostial disease
    • Bifurcation disease
    • Use of guide extension catheters
    • Balloon post-dilatation
    • Greater number of deployed stents
  • Most common cause:18 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.19

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.19 However, LSD has been reported with other DES, suggesting that risk factors outside of stent platform design may have a role in LSD.19
  • LSD while rare, is under-recognized, and may result in:18
    • 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.