Key Guidelines

• 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization
• Clinical use of intracoronary imaging. Part 1: guidance and optimization of coronary interventions
• Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making

Background

IVUS

• Anatomic assessment of artery
• Flow limitation inferred but correlates with FFR
• Main benefit is vessel and lesion size and characterization
• Decades of evidence

OCT

• Anatomic assessment of artery
• Uses near-infrared light to produce backscatter
• 10 times the resolution of IVUS
• Requires blood clearance for imaging
• Similar clinical results to IVUS
• Data pending on who clinically benefits

When to use?

Lesion Severity

IVUS

Lesion Severity

In patients with intermediate stenosis of the left main artery, intravascular ultrasound (IVUS) is reasonable to help define lesion severity (Class IIa).

• "IVUS offers significantly greater spatial resolution than angiography alone (IVUS axial resolution: 100-150  μm,  and  coronary  angiography  axial  resolution: 300 μm)"

• "Cross-sectional images provide accurate evaluation of lesion characteristics, including lumen  dimensions,  lesion  length,  plaque  morphology  and  location, thrombus, dissection, and stent apposition and expansion."

Lesion Severity

In patients with intermediate stenosis of the left main artery, intravascular ultrasound (IVUS) is reasonable to help define lesion severity (Class IIa).

• "Minimal lumen area on IVUS has been shown to correlate with physiological indices"

• "In indeterminate  LM,  studies  have  shown  that  IVUS  evaluation  with  deferral of intervention for a minimum lumen area of ≥6 to 7.5 mm2 is safe, although a smaller cut-off  (4.5–4.8  mm2)  may  be  more  appropriate  in  patients of Asian descent."

Key Study

• "The present meta-analysis demonstrates a significant reduction in MACE with IVUS-guided DES implantation in complex coronary lesions."

OCT and Left Main

• Compared to IVUS, "OCT  has  more  limited  depth  of  imaging. It also requires blood clearance through the use of contrast injection, which diminishes its use in ostial left main disease"

Procedural Guidance

IVUS

Procedural Guidance

In patients undergoing coronary stent implantation, IVUS can be useful for procedural guidance, particularly in cases of left main or complex coronary artery stenting, to reduce ischemic events (Class IIa).

• "IVUS  enables  full-thickness  visibility of the vessel wall, enabling pre-PCI assessment of  plaque  burden,  extent  of  calcification,  lesion  length,  and external elastic lamina diameter for stent sizing and post-PCI  assessment  of  minimum  stent  area,  malapposition,  underexpansion,  tissue  protrusion,  edge  disease,  and edge dissection."

Key Study

• "The present study demonstrates that IVUS-guided DES implantation significantly improved clinical outcome in all-comers, particularly for patients who had an IVUS-defined optimal procedure, compared with angiography guidance."

OCT

Procedural Guidance

In patients undergoing coronary stent implantation, OCT is a reasonable alternative to IVUS for procedural guidance, except in ostial left main disease (Class IIa).

• "OCT uses infrared light to gen-erate high-resolution images of the vessel wall, with par-ticular  advantages  in  assessing  calcium  thickness,  lipid,  thrombus, fibroatheroma, and plaque rupture, as well as stent strut neointimal thickness and apposition, and edge dissections"

Key Study

• "OCT-guided PCI using a specific reference segment external elastic lamina-based stent optimisation strategy was safe and resulted in similar minimum stent area to that of IVUS-guided PCI. These data warrant a large-scale randomised trial to establish whether or not OCT guidance results in superior clinical outcomes to angiography guidance"

• ILLUMIEN IV on-going comparing OCT to angiography

Procedural Guidance

https://academic.oup.com/eurheartj/article/39/35/3281/5001185

Stent Failure

Stent Failure

In patients with stent failure, IVUS or OCT is reasonable to determine the mechanism of stent failure (Class IIa).

• "Assessment  of  the  cause  of  stent  thrombosis  with  intracoronary  imaging  is  important to guide subsequent treatment. Similarly, advanced  imaging  techniques  have  an  important  role in detecting underlying mechanical and pathophysiological  factors  that  contribute  to  in-stent  restenosis  (ISR),  such  as  neointimal  hyperplasia,  stent  underexpansion,  and  fractures."

Stent Failure

In patients with stent failure, IVUS or OCT is reasonable to determine the mechanism of stent failure (Class IIa).

• "Registry and case series data  have  demonstrated  that  IVUS  and  OCT  can  be  useful  for  evaluating  the  mechanisms  of  stent  restenosis  and  stent  thrombosis."

• "OCT  is  better   at   differentiating   between   stent-related   mechanisms,  whereas  IVUS  is  preferred  for  in-depth vessel wall characterization."

Key Study

• "Use of OCT identified an underlying morphological abnormality associated with ST in 97% of the cases"

• "Malapposition and neoatherosclerosis rupture were the main causes of LST and VLST"

• "Malapposition and underexpansion were prominent mechanisms for AST and SAST"

Examples

Disease Severity

Left Main Assessment

https://academic.oup.com/eurheartj/article/40/31/2566/5491794

Procedural Guidance

Calcium Assessment

https://www.acc.org/latest-in-cardiology/articles/2016/06/13/10/01/intravascular-oct-in-pci

Calcium Assessment

https://www.acc.org/latest-in-cardiology/articles/2016/06/13/10/01/intravascular-oct-in-pci

Stent Assessment

https://www.acc.org/latest-in-cardiology/articles/2016/06/13/10/01/intravascular-oct-in-pci

Stent Failure

Stent Underexpansion

https://www.jacc.org/doi/abs/10.1016/j.jacc.2010.07.028

Stent Fracture

https://www.jacc.org/doi/abs/10.1016/j.jacc.2010.07.028

Stent

Thrombosis

https://academic.oup.com/eurheartj/article/37/15/1208/1748814