IVUS Guided PCI: New Expansion Threshold

Intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) has been shown to improve clinical outcomes vs the conventional angiography guided PCI. This benefit has been supported by robust evidence and recommended by international guidelines for complex PCI. However, when using IVUS, there is an ongoing debate as to the optimal stent expansion threshold to ensure long term clinical benefits.

Lee et al. has carried out a prespecified analysis of individual data from 3 randomized studies on the use of IVUS (IVUS-XPL, ULTIMATE and IVUS-ACS), with a total 6,290 patients. This meta-analysis sought to validate different stent expansion criteria — both absolute and relative — assessed by IVUS, and look into its link to one year outcomes. 

The cohort compared IVUS guided PCI outcomes (n=3,082) vs angiography guided PCI (n=3,208); the first group was further classified as “optimized” or “non-optimized” according to seven expansion criteria.

Absolute criteria were: MSA >5.5 mm² and MSA >5.0 mm². Relative criteria compared MSA to distal reference lumen area (DRLA) and average lumen area (AvLA, average between proximal and distal references).

The patient population were mean age 64, 72.4% were men, and 16.3% had stable angina (most with acute coronary syndrome). IVUS analysis was done to the anterior descending (56%), right coronary (23.9%), circumflex (15%) and left main (5.2%).

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Among the metrics, the most relevant criterion was absolute MSA threshold >5.5 mm², reaching 61% of IVUS guided cases. Patients reaching this target presented a significantly lower rate of target vessel failure at one year: 1.45% vs 3.86% for non-optimized patients (adjusted HR: 0.45; CI95%: 0.26–0.75; p=0.002) and 5.07% in angiography guided patients.

Likewise, this same criterion was associated to lower incidence of the composite of cardiac death or targe vessel infarction (adjusted HR: 0.39; CI95%: 0.17–0.91; p=0.028). Instead, when using the lower MSA cutoff value >5.0 mm², there were no significant differences, which reinforces the specificity of the 5.5 mm² criterion.

As to the relative criteria (MSA >100% DRLA, >90% DRLA, >80% DRLA, >90% AvLA and >80% AvLA), even though there was a tendency towards better outcomes among optimized patients, there was no statistical significance, which indicates these relative parameters are not as predictive as the absolute threshold when it comes to identifying clinical risk. 

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The exploratory analysis with ROC curves and proportion risk models confirmed MSA >5.5 mm² is the best predictor of a primary event, superior even to angiographic parameters such as post PCI minimal lumen diameter.

Conclusions

These findings support a paradigm shift, one that establishes a clear absolute value (MSA >5.5 mm²) as practical and clinically validated target for planning and stent optimization, which will facilitate decision making during IVUS guided PCI. 

Original Title: Validation of Intravascular Ultrasound-Defined Optimal Stent Expansion Criteria for Favorable 1-Year Clinical Outcomes.

Reference: Lee SH, Jin X, Lee YJ, Kan J, Ge Z, Lee SJ, Hong SJ, Ahn CM, Kim JS, Kim BK, Ko YG, Choi D, Jang Y, Stone GW, Mintz GS, Chen SL, Hong MK. Validation of Intravascular Ultrasound-Defined Optimal Stent Expansion Criteria for Favorable 1-Year Clinical Outcomes. JACC Cardiovasc Interv. 2025 Sep 22;18(18):2197-2205. doi: 10.1016/j.jcin.2025.07.024. PMID: 40992799.