#ivus #oct #intracoronary-imaging #pci #coronary-artery-disease #complex-pci #left-main-pci

Intracoronary Imaging-Guided PCI

Definition

Intracoronary imaging-guided PCI refers to the use of intravascular ultrasound (IVUS) or optical coherence tomography (OCT) during percutaneous coronary intervention to guide stent selection, sizing, positioning, and post-deployment optimisation, as opposed to conventional angiography-guided PCI alone. IVUS provides high-resolution cross-sectional tomographic imaging of coronary anatomy and plaque burden; OCT provides higher spatial resolution but lower tissue penetration. Both modalities allow assessment of stent expansion, apposition, edge dissection, and plaque burden in ways that angiography cannot.

Key Concepts

Mechanism of Benefit

Intracoronary imaging enables accurate vessel sizing and lesion length assessment, ensuring appropriate stent selection
Post-stent IVUS/OCT identifies: under-expansion, malapposition, geographic miss, edge dissection — all linked to stent failure, restenosis, and stent thrombosis
IVUS-triggered optimisation (additional balloon dilation or stenting) is initiated in 40–50% of procedures where imaging is performed (sources/ivus-chip-nejm-2026, rating: high)

Prior Positive Evidence (Predominantly Asian RCTs)

IVUS-XPL (JAMA 2015): IVUS-guided vs angiography-guided DES implantation in long lesions — reduced TVF at 1 year (2.9% vs 5.8%; P=0.007)
ULTIMATE (JACC 2018/2021): IVUS-guided vs angiography-guided DES — target-vessel failure HR 0.53 at 3 years; benefit driven by reduced TLR; confirmed at 3-year follow-up
RENOVATE-COMPLEX-PCI (NEJM 2023): Intravascular imaging vs angiography for complex PCI — primary composite HR 0.64 (P=0.008); driven by target-vessel revascularisation; conducted in Korea
Network meta-analysis (Lancet 2024, Stone et al.): IVUS guidance associated with significant reduction in ischaemic events and stent thrombosis across 31 studies/17,882 patients

Neutral Results in Western RCTs

ILUMIEN IV (NEJM 2023): OCT-guided vs angiography-guided PCI for complex lesions or diabetes — no superiority for TVF at 2 years; stent thrombosis numerically lower with OCT
IVUS-CHIP (NEJM 2026, N=2020): IVUS-guided vs angiography-guided complex high-risk PCI (CHIP) at 37 European centres — TVF 13.9% vs 11.1%; HR 1.25 (P=0.08); not superior. Stent thrombosis lower with IVUS (0.2% vs 1.0%; HR 0.20). Stent-optimisation criteria met in only 48% of IVUS-guided lesions due to high calcification burden. (sources/ivus-chip-nejm-2026, rating: high)
IVUS-OPTIMAL (NEJM 2026, N=806): IVUS-guided vs angiography-guided PCI specifically for unprotected left main disease at 28 European centres — patient-oriented composite 33.7% vs 30.9%; HR 1.11 (P=0.40); not superior. No difference across any secondary endpoint. Unexpected stroke signal in IVUS arm (3.0% vs 1.0%; HR 3.11; considered possibly chance). (sources/ivus-optimal-nejm-2026, rating: high)

Guideline Context (Pre-2026 Evidence)

2024 ESC Chronic Coronary Syndromes Guidelines: Class IA recommendation for intracoronary imaging (IVUS or OCT) for PCI of anatomically complex lesions including left main disease (sources/ACS-AHA-2025, rating: very high)
2025 ACC/AHA ACS Guidelines: Class I/A for intracoronary imaging in left main or complex lesion PCI (sources/ACS-AHA-2025, rating: very high)
Both guideline recommendations were established primarily on the basis of Asian RCT evidence and observational data; the 2026 European RCTs were not yet available at the time of guideline publication

Possible Explanations for Neutral Western Results

Expertise and volume effect: High-volume European centres with experienced operators have already internalised IVUS-derived principles (systematic lesion preparation, sizing algorithms, aggressive post-dilation) into their angiography-guided practice, narrowing the gap
Investigator calibration bias: Operators experienced in IVUS may unconsciously adjust angiography-guided strategy to IVUS-equivalent standards when working in an open-label trial
High calcification burden: In IVUS-CHIP, 42.2% had severe calcifications; stent-optimisation criteria were met in only 48% of IVUS-guided lesions, suggesting that imaging may identify suboptimal results that cannot always be corrected due to severe disease
Event rate lower than anticipated in control arm: Improved modern PCI techniques across the board (better stents, P2Y12 therapy, procedural algorithms) have reduced baseline event rates
Stent thrombosis signal preserved: Both ILUMIEN IV and IVUS-CHIP showed numerically lower stent thrombosis with imaging despite neutral primary outcome — suggests mechanistic value in ensuring adequate apposition even without overall MACE benefit

Contradictions / Open Questions

Guideline vs 2026 RCT divergence: Current Class IA recommendations for IVUS in complex and left main PCI are based on evidence that predates both IVUS-CHIP and IVUS-OPTIMAL (both published March 30, 2026, NEJM). Both large European RCTs failed to demonstrate superiority of routine IVUS guidance. Guideline updates may be needed. (sources/ivus-chip-nejm-2026, rating: high; sources/ivus-optimal-nejm-2026, rating: high)
Asian vs Western evidence discrepancy: RENOVATE-COMPLEX-PCI (Korea) was positive; IVUS-CHIP and IVUS-OPTIMAL (Europe) were neutral using similar eligibility criteria. Whether this reflects operator expertise, case-mix differences, or population-level variation in baseline event rates is unresolved. IVUS-CHIP enrolled a substantially higher-risk population (severe calcification 42.2% vs 13.5% in RENOVATE-COMPLEX-PCI).
Stent thrombosis vs hard outcomes: Both ILUMIEN IV and IVUS-CHIP showed lower stent thrombosis with imaging guidance (HR ~0.20 in IVUS-CHIP) despite no primary composite benefit. Whether reduction in stent thrombosis — a severe but rare complication — justifies universal IVUS use is debated.
OPTIMAL stroke signal: Stroke was 3× higher in the IVUS arm of OPTIMAL (HR 3.11; 3.0% vs 1.0%); this is unexpected, unexplained, and may be a chance finding given low event numbers, but cannot be dismissed without further data. (sources/ivus-optimal-nejm-2026, rating: high)
Who benefits? Subgroup analyses suggest possible benefit in lower-volume centres or less-experienced operators; routine IVUS may still add value in lower-expertise settings not represented in these trials.

Connections

Related to entities/Left-Main-Coronary-Disease — OPTIMAL trial specifically targets LMCA PCI
Related to entities/Chronic-Coronary-Disease — complex PCI management strategy; IVUS-CHIP enrolled predominantly CCS patients
Related to entities/Acute-Coronary-Syndrome — IVUS/OCT also Class I in ACS complex PCI per 2025 AHA guidelines
Related to concepts/DAPT-Strategies — stent optimisation affects downstream DAPT decision