Imaging of Coronary Revascularization: Stent and CABG

 

Subset of CAD by anatomy

Classa

For prognosis

Left main >50 %b

I

Any proximal LAD stenosis >50 %b

I

2VD or 3VD with impaired LV functionb

I

Proven large area of ischemia (>10 % of LV)

I

Single remaining patent vessel >50 % stenosisb

I

1VD without proximal LAD and without >10 % ischemia

III

For symptoms

Any stenosis >50 % with limiting angina or angina equivalent, unresponsive to OMT

I

Dyspnea/CHD and >10 % LV ischemia/viability supplied by >50 % stenotic artery

IIa

No limiting symptoms with OMT

III


Modified from the ESC/EACTS guidelines 2010 [2]

CHD chronic heart failure, LAD left anterior descending, LV left ventricle, OMT optimal medical therapy, VD vessel disease

aClasses of recommendations

Class I: evidence that a given treatment is beneficial, useful, and effective

Class IIa: weight of evidence is in favor of usefulness

Class IIb: usefulness of treatment is less well established by evidence

Class III: evidence that the given treatment is not useful/effective, and in some cases may be harmful

bWith documented ischemia or FFR <0.80 for angiographic diameter stenosis 50–90 %





  • Patients with persistent limiting symptoms (angina or angina equivalent) despite OMT for symptomatic benefit.


  • Certain anatomical patterns of disease (Table 8.1) or a proven significant ischemic territory even in asymptomatic patients for prognostic benefit. Significant LM stenosis and significant proximal LAD disease, especially in the presence of multivessel CAD, are strong indications for revascularization.







    8.1.2 Indication for CABG Versus PCI in Stable CAD






    • CABG appears to be better in terms of survival benefit as well as reduction of revascularization in patients with high risk of CAD; multivessel disease with complex morphology and left main disease (Table 8.2) [2].


      Table 8.2
      Indications for CABG versus PCI in stable CAD patients















































      Subset of CAD by anatomy
      Favors CABG
      Favors PCI

      Classa

      Classa

      1VD or 2VD – non-proximal LAD
      IIb
      I

      1VD or 2VD – proximal LAD
      I
      IIa

      3VD simple lesions, full-functional revascularization achievable with PCI, SYNTAX score ≤22
      I
      IIa

      3VD complex lesions, incomplete revascularization achievable with PCI, SYNTAX score >22
      I
      III

      Left main (isolated or 1VD, ostium/shaft)
      I
      IIa

      Left main (isolated or 1VD, distal bifurcation)
      I
      IIb

      Left main + 2VD or 3VD, SYNTAX score ≤32
      I
      IIb

      Left main + 2VD or 3VD, SYNTAX score >32
      I
      III


      Modified from the ESC/EACTS guidelines 2010 [2]

      VD vessel disease, LAD left anterior descending

      aSame with class of recommendations in Table 8.1



    8.2 Coronary Stent



    8.2.1 Clinical Background






    • Coronary stents, which was developed in the mid-1980s, have been preferred method of performing PCI and replaced plain balloon angioplasty [3].


    • Drug-eluting stents (DES) are highly efficacious at reducing the risk of target-vessel revascularization without an increase in any safety outcomes, including stent thrombosis [4].


    • In contemporary PCI practice, newer-generation DES with novel coating and biodegradable stents are widely used.


    • Newer-generation DES have thinner stent struts for improvement of stent deliverability and more biocompatible polymers coating for reduction of in-stent restenosis (Fig. 8.1) (Table 8.3).

      A311690_1_En_8_Fig1_HTML.jpg


      Fig. 8.1
      First-generation (a) and second-generation DES on CT image. (a) Curved planar CT image of sirolimus-eluting stent (Cypher) shows relative thick strut. (b) Curved planar CT image of zotarolimus-eluting stent (Endeavor) shows thin strut



      Table 8.3
      First- and second-generation DES














































      Stent name
      Drug
      Metal
      Polymer thickness (μm)
      Strut thickness (μm)

      Cypher
      Sirolimus
      Stainless steel
      12.6
      140

      Taxus Express
      Paclitaxel
      Stainless steel
      16.0
      132

      Taxus Liberte
      Paclitaxel
      Stainless steel
      16.0
      97

      Endeavor
      Zotarolimus
      Cobalt chromium
      4.1
      91

      Xience V
      Everolimus
      Cobalt chromium
      7.6
      81


      Modified from reference [3]


    8.2.2 Application of CTA for Coronary Stent Imaging






    • Reduction of motion artifact and achievement of optimal contrast enhancement of CT angiography are very important for stent imaging.





    • Image reconstruction and analysis tips for good quality of image.



      • Use sharp kernel reconstruction for reduction of blooming artifact (Fig. 8.2).


      • Use wide window of ≥700 HU with a center of about 200 HU for an acceptable trade-off between blooming and visibility of the stent lumen.


      • Use reconstruction mode of high spatial resolution, if available (Fig. 8.3).


      • Correct centerline of curved planar image carefully (Fig. 8.4).


      • Thick-slab maximal intensity projection (MIP) image may be helpful for delineation of a mechanical deformity (e.g., fracture) of the stent (Fig. 8.5).


      • Generate cross-sectional image of the stent to evaluate in-stent restenosis (Fig. 8.6).




    • Application of CTA for coronary stent [5]



      • In-stent restenosis


      • Mechanical deformity including stent fracture, longitudinal compression, and inadequate expansion


      • Edge stenosis and peri-stent plaque


      • Jailed branches


      • Late stent thrombosis


      • Bifurcation stents


      • Aneurysm of the coronary artery


    A311690_1_En_8_Fig2_HTML.jpg


    Fig. 8.2
    Effect of image reconstruction kernel on image quality. Curved planar CT image of sirolimus-eluting stent (Cypher) with soft reconstruction kernel (B26; Siemens, Definition FLASH CT) (a) and sharp reconstruction kernel (B46) (b). In the sharp kernel image, blooming artifact from stent strut was markedly reduced as compared with that of soft kernel image


    A311690_1_En_8_Fig3_HTML.jpg
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    Jul 13, 2016 | Posted by in CARDIOLOGY | Comments Off on Imaging of Coronary Revascularization: Stent and CABG

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