Current Approach for Optimizing PCI Using IVUS
IVUS guidance during PCI significantly improves clinical outcomes by enabling optimal stent deployment, reducing stent thrombosis, and minimizing restenosis compared to angiography-guided procedures. 1
Pre-Intervention Assessment
- IVUS provides critical pre-intervention assessment of plaque composition, lesion characteristics, and identification of optimal reference segments and landing zones for stent placement 1
- Pre-intervention IVUS helps select optimal stent length and diameter, preventing systematic undersizing of stents 1
- IVUS should be performed after administration of intracoronary nitroglycerine, beginning at least 20mm distal to the area of interest and ending at the vessel ostium 1
- IVUS helps identify vulnerable plaques at risk of future rupture, even if not anatomically or physiologically significant, which may guide intensification of medical therapy 1
Lesion Preparation and Stent Deployment
- IVUS improves detection, localization, and characterization of coronary calcification (thickness, angle, length) to guide appropriate adjunctive therapies (angioplasty, atherectomy, lithotripsy) 1
- IVUS-based scoring systems help identify calcified stenoses at risk for stent under-expansion that may require adjunctive modification before stent implantation 1
- Stent lengths should be selected to cover from the most normal distal segment to the most normal proximal segment 1
- Avoid stenting into reference segments with restricted lumen areas and plaque burden >50% or segments with large lipid plaque or significant calcification 1
- For tapering vessels (like left main and bifurcations), IVUS helps in selecting appropriate stent sizes and determining when an upfront 2-stent bifurcation strategy is preferable 1, 2
IVUS Optimization Criteria from ULTIMATE Trial
- Minimum lumen area (MLA) in the IVUS-stented segment >5.0 mm² or 90% of the MLA at the distal reference segments 1
- <50% plaque burden within 5mm proximal or distal to the stent edge 1
- No edge dissection involving the media with a length >3mm 1
Post-Procedure Assessment
Post-procedure IVUS confirms optimal procedural endpoints and identifies complications requiring correction 1
Key complications to identify include:
Minor edge dissections limited to the intima, involving <45° circumference, and measuring <2mm in length typically don't require correction 1
Larger dissections with significant residual plaque burden, extensive lateral (>60°) and longitudinal (>2mm) extension, involvement of deeper layers, or located distal to the stent require intervention 1
Special Considerations for Complex Lesions
- Left main interventions: IVUS is particularly important with specific cut-off values (distal LM >7-9mm² and proximal LM >8-10mm² in different populations) 1, 2
- Chronic total occlusions (CTOs): IVUS helps resolve proximal cap ambiguity, delineate cap morphology, and guide true-lumen wiring 1, 2
- Bifurcation lesions: IVUS aids in determining optimal stenting strategy and proper stent sizing in tapering vessels 1, 2
- Calcified lesions: IVUS guides appropriate lesion preparation strategies before stent deployment 1, 2
Clinical Benefits of IVUS-Guided PCI
- Compared to angiography-guided PCI, IVUS guidance is associated with:
Common Pitfalls and Caveats
- Despite proven benefits, IVUS is used in <15% of all PCI procedures due to unfamiliarity with equipment, knowledge gaps in interpretation, perception of increased procedural times, and reimbursement concerns 1
- IVUS should be used cautiously in spontaneous coronary artery dissection due to risks of manipulating the dissected artery 1
- Air bubbles between the catheter sheath and IVUS transducer can degrade image quality in mechanical (but not solid-state) catheters 1
- Stent malapposition should be distinguished from stent underexpansion, as most acute malapposition resolves over time without affecting long-term stent failure rates (unless underexpansion is present) 1