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Flattery et al. Vessel Plus 2024;8:26 https://dx.doi.org/10.20517/2574-1209.2023.130 Page 7 of 11
IVUS-GUIDED VS. ALTERNATIVE INTRACORONARY IMAGING OR PHYSIOLOGY-

GUIDED PCI
IVUS guidance for PCI has also been compared with other technologies intended to optimize PCI
outcomes, including Fractional Flow Reserve (FFR) and OCT. Though not intended to be a comprehensive
review, four recent large-scale trials were identified and included [Table 3].

IVUS vs. physiology
Unlike IVUS, physiologic assessment using fractional flow reserve (FFR) or non-hyperemic pressure ratios
(NHPR) such as instantaneous wave-free ratio (iFR) do not provide visual information about the anatomy
of the coronary artery. Instead, FFR and NHPRs give functional information about the degree of ischemia of
a coronary lesion and its physiologic significance. Intravascular imaging and physiologic assessments
provide different and often complementary information regarding coronary anatomy and physiology.

The multinational FLAVOUR trial, published in 2022 from 18 centers in China and Korea, evaluated
whether IVUS- or FFR-guidance for PCI yielded improved outcomes for angiographically intermediate
lesions (40%-70% occlusion by visual estimation on coronary angiography) in 1,682 patients . This study
[23]
demonstrated no significant difference in the primary composite outcome of death, myocardial infarction,
and revascularization at 24 months between study groups; however, fewer patients underwent PCI (44.4%
vs. 65.3%, difference - 20.9% (95% confidence interval -25.7 to -16.1)) and fewer stents were placed per
patient [0.6+/-0.9 vs. 0.9+/-1.0, difference - 0.3 (95% confidence interval -0.4 to -0.3)] in the patients
assigned to the FFR arm compared with the IVUS arm. These data support the paradigm that physiology
should be used to assess the indication for PCI, while intravascular imaging should be used to optimize the
interventional result.

IVUS vs. OCT
OCT [historically termed optical frequency domain imaging (OFDI)] is a more recently developed light-
based intracoronary imaging technology analogous to IVUS in that it also yields real-time, cross-sectional,
360-degree imaging using an intracoronary catheter. The differences in IVUS and OCT technologies and
[24]
performance techniques have been previously described ; however, whether one technique yields superior
clinical outcomes has been less well-defined.

To answer this question, the multinational ILUMIEN III: OPTIMIZE PCI trial, published in 2016,
compared procedural success and 30-day clinical outcomes in IVUS guidance, OCT guidance, and
angiography guidance in 450 patients at 29 hospitals in eight countries . In this study, no significant
[25]
difference was detected between any study group for either the primary procedural outcome (minimal stent
area) or either procedural or 30-day MACE. Similarly, the 2017 OPINION trial, which enrolled 829 patients
from 42 medical centers in Japan, demonstrated no difference in clinical outcomes (primary outcome TVF
defined as cardiac death, target-vessel related MI, and ischemia-driven TVR) at one year when comparing
IVUS vs. OCT guidance for PCI with DES . These results were again replicated in the 2023 OCTIVUS
[26]
trial, which enrolled 2,008 patients in nine centers in South Korea and demonstrated noninferiority of OCT
[27]
guidance compared with IVUS guidance with respect to two-year MACE .

DISCUSSION
In this review, we have examined the English-language RCTs that have evaluated the potential benefit of
IVUS guidance in the performance and optimization of PCI. These studies have evolved with PCI and IVUS
technology, with the earliest studies including procedures limited to PTCA and BMS implantation, to