Timir Paul, MD, PhD, FSCAI; Jimmy Kerrigan, MD, FSCAI; and Jayant Bagai, MD, FSCAI
Several studies have shown the clinical benefits of intravascular ultrasound (IVUS) guidance for complex percutaneous coronary intervention (PCI) such as unprotected left main, chronic total occlusion (CTO) and bifurcation lesions.1–3 In this Tip of The Month, we will provide practical pointers on how to optimally utilize IVUS to guide PCI.
Pre-Intervention Assessment and Procedural Planning/Guidance
- Assess the plaque burden and morphology (fibrofatty, fibrous, calcified, lipid rich, or mixed) and the type (superficial versus deep, circumferential, eccentric, or nodular) and quantity (arc, depth, and length) of calcification.
- Determine the vessel size (media to media), lumen area, and lesion length (if using motorized pullback or co-registration).
- Assess ambiguous or difficult-to-visualize lesions such as aorto-ostial, eccentric, left main, bifurcations, aneurysms, thrombus, plaque protrusion, and filling defects.
- Diagnose cardiac transplant vasculopathy and determine the culprit lesion in acute coronary syndrome (ruptured plaque) and spontaneous coronary artery dissection.4, 5
- Determine location of ambiguous wire position (true lumen versus sub-intimal) and to guide ostial stenting in the event of an aortic cusp dissection.
- IVUS is invaluable in all stages of CTO PCI and to conserve contrast in patients with advanced renal insufficiency (allowing low contrast or, rarely, contrast-free PCI).
- Prevent geographic miss (coverage of entire segment with significant plaque burden) and precise ostial stenting.
- Characterize tissue using the virtual histology feature of phased-array IVUS.
- Determine the adequacy of stent deployment (size, apposition, expansion, and geographic miss).
- Evaluate the etiology of acute complications (dissection, thrombus, intramural hematoma, and tissue protrusion).
- Use ChromaFloâ with phased-array imaging systems for the diagnosis of stent malapposition, dissection, and thrombus as well as for the assessment of side branch flow.
- Evaluate post-PCI minimum stent cross-sectional area (MSA), especially in unprotected left main PCI and bifurcation stenting. Ensure adequate MSA in the left main, carina, ostial left anterior descending, and ostial left circumflex coronaries, and to assess for patent side branch ostia during provisional stenting.
- Diagnose and assess the treatment of longitudinal stent deformation.
Recent Evidence Supporting the Benefit of IVUS for Complex PCI
A five-year follow-up of the IVUS-XPL randomized controlled trial (RCT) demonstrated that IVUS-guided PCI resulted in a significantly lower rate of major adverse cardiac events (MACE) when compared with angiography-guided PCI in long lesions.6 Three-year outcomes of the ULTIMATE RCT revealed that compared to angiography guidance, IVUS guidance was associated with significantly lower rates of target vessel failure and stent thrombosis in all comers.7 In addition, there is a wealth of data from registries and small RCTs that demonstrates a significant reduction in in-hospital MACE, 30-day, and 12-month mortality with IVUS guidance of unprotected left main PCI.1, 8
Current Guidelines on the Use of IVUS in PCI
The 2021 American Heart Association/American College of Cardiology, and Society of Cardiovascular Angiography and Interventions (AHA/ACC/SCAI) Guideline for Coronary Artery Revascularization gives a Class 2a recommendation for IVUS in patients undergoing coronary stent implantation for procedural guidance, particularly in cases of left main or complex coronary artery stenting, to reduce ischemic events, assess the intermediate stenosis of the left main artery, and assess the mechanism of stent failure.9
Table 1. Algorithmic Approach for Use of IVUS During PCI Procedures10, 11
Lesion assessment prior to stenting
Morphology: The lesion preparation strategy (most useful in cases of heavy calcification) should be determined.12 See Figures 1, 3, 4, and 5.
Length: If using motorized pullback at fixed speed or co-registration, proximal and distal stent landing zones should ideally have less than 50% plaque burden.
1. The distal reference media-to-media average vessel diameter should be sized down to the nearest stent size.
2. If the EEM or media-adventitia cannot be defined, the distal reference average lumen diameter should be calculated and sized up to the nearest stent size.
Assessment of post-stent result
Medial: A medial (deep) dissection > 60-degree arc and/or > 3mm in length from the stent edge should be covered with an additional stent. See Figure 2.
Apposition: Gross malapposition with a length > 3mm should be corrected with post-dilatation using larger semi-compliant balloons at nominal pressure.
eXpansion: The MSA should be at least 80% and ideally > 90% of distal reference lumen CSA or MSA > 5–5.5mm2 for non-left main and > 8mm2 for left main lesions.13
IVUS: intravascular ultrasound; PCI: percutaneous coronary intervention; EEM: external elastic membrane; MSA: minimum stent cross-sectional area; CSA: cross-sectional area. Rows 2 and 3 of this table are part of the so-called MLD-MAX algorithm, which has been used during optical coherence tomography (OCT) guidance for PCI, but similar principles are useful for IVUS-guided PCI.
Studies have shown IVUS-guided PCI significantly improves clinical outcomes and lowers mortality, MACE, and stent failure. An algorithmic approach in utilizing IVUS to guide PCI is highly beneficial and should be considered for most contemporary PCI procedures.
- Andell P, Karlsson S, Mohammad MA, et al. Intravascular Ultrasound Guidance Is Associated With Better Outcome in Patients Undergoing Unprotected Left Main Coronary Artery Stenting Compared With Angiography Guidance Alone. Circ Cardiovasc Interv. 2017 May;10(5): e004813.
- Tian NL, Gami SK, Ye F, et al. Angiographic and clinical comparisons of intravascular ultrasound versus angiography-guided drug-eluting stent implantation for patients with chronic total occlusion lesions: two-year results from a randomized AIR-CTO study. EuroIntervention. 2015 Apr;10(12): 1409–17.
- Chen L, Xu T, Xue XJ, et al. Intravascular ultrasound-guided drug-eluting stent implantation is associated with improved clinical outcomes in patients with unstable angina and complex coronary artery true bifurcation lesions. Int J Cardiovasc Imaging. 2018 (Nov); 34(11):1685–96.
- Jasti V, Ivan E, Yalamanchili V, et al. Correlations between fractional flow reserve and intravascular ultrasound in patients with an ambiguous left main coronary artery stenosis. 2004 Nov 2;110(18):2831–6.
- Briguori C, Anzuini A, Airoldi F, et al. Intravascular ultrasound criteria for the assessment of the functional significance of intermediate coronary artery stenoses and comparison with fractional flow reserve. Am J Cardiol. 2001 Jan 15; 87(2):136–41.
- Hong SJ, Mintz GS, Ahn CM, et al. Effect of Intravascular Ultrasound-Guided Drug-Eluting Stent Implantation: 5-Year Follow-Up of the IVUS-XPL Randomized Trial. JAAC Cardiovasc Interv. 2020 Jan 13; 13(1):62–71.
- Gao XF, Ge Z, Kong XQ, et al. 3-Year Outcomes of the ULTIMATE Trial Comparing Intravascular Ultrasound Versus Angiography-Guided Drug-Eluting Stent Implantation. JACC Cardiovasc Interv. 2021 Feb 8;14(3):247–57.
- Kinnaird T, Johnson T, Anderson R, et al. Intravascular Imaging and 12-Month Mortality After Unprotected Left Main Stem PCI: An Analysis From the British Cardiovascular Intervention Society Database. JACC Cardiovasc Interv. 2020 Feb 10;13(3):346–57.
- Lawton JS, Tamis-Holland JE, Bangalore S, et al. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022 Jan 18;145(3):e4–e17.
- Räber L, Mintz GS, Koskinas KC, et al. Clinical use of intracoronary imaging. Part 1: guidance and optimization of coronary interventions. An expert consensus document of the European Association of Percutaneous Cardiovascular Interventions. Euro Heart J. 2018 Sep 14;39(35):3281–3300.
- Johnson TW, Räber L, di Mario C, et al. Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Interventions. Eur Heart J. 2019 Aug 14;40(31):2566–84.
- Zhang M, Matsumura M, Usui E, et al. Intravascular Ultrasound-Derived Calcium Score to Predict Stent Expansion in Severely Calcified Lesions. Circ Cardiovasc Interv. 2021 Oct;14(10):e010296.
- Kang SJ, Ahn JM, Song H, et al. Comprehensive intravascular ultrasound assessment of stent area and its impact on restenosis and adverse cardiac events in 403 patients with unprotected left main disease. Circ Cardiovasc Interv. 2011 Dec 1;4(6):562–9.
Figure 1. Focal severe instent restenosis (ISR) occuring > five years after drug-eluting stent implantation resistant to noncompliant (NC), cutting, and lithotripsy balloons. The mechanism was severe fibrotic ISR, which responded to laser with contrast injection followed by very high-pressure NC balloon.
Figure 2. A deep medial dissection (6 to 12 o’clock) occurring proximal to the stent edge.
Figure 3. Concentric superficial calcification causing shadowing and reverberation.
Figure 4. Fibrofatty plaque (mostly fatty) with a more fibrotic segment from 11 to 12 o'clock and deep calcium from 12 to 2 o'clock and 3 to 5 o'clock.
Figure 5. Calcific nodule (at 8 o'clock) with borders highlighted using ChromaFloâ; otherwise noted is mixed calcific and fibrotic plaque.
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