Three recently published randomized trials, OPTIMAL, IVUS-CHIP, and DKCRUSH VIII, showed inconsistent results regarding a potential benefit of intravascular imaging (IVI) in complex percutaneous coronary intervention (PCI). Methodologically, however, there are substantial differences between the studies, limiting direct comparability.
The randomized, controlled, multicenter OPTIMAL trial, conducted at 28 European high-volume centers, was a superiority trial including 806 patients with a mean SYNTAX score of approximately 30. Surprisingly, in unprotected left main PCI, it failed to demonstrate a benefit of IVUS-guided PCI over angiography-guided PCI. The primary endpoint was a patient-oriented composite endpoint consisting of stroke, myocardial infarction, revascularization, or death from any cause. After a median follow-up of 2.9 years, this endpoint occurred in 135 of 401 patients, 33.7%, in the IVUS group and in 125 of 405 patients, 30.9%, in the angiography-guided group (HR 1.11; 95% CI 0.87–1.42; p=0.40). Secondary endpoints also did not differ significantly.
The randomized, controlled IVUS-CHIP trial, including 2,020 patients with a mean SYNTAX score of approximately 25, likewise showed no superiority of the IVUS-guided strategy in complex high-risk PCI. The primary endpoint was target vessel failure (TVF), defined as a composite of cardiac death, target-vessel myocardial infarction, or clinically indicated target-vessel revascularization. After a median follow-up of 19 months, the primary endpoint occurred in 140 of 1,010 patients, 13.9%, in the IVUS group and in 112 of 1,009 patients, 11.1%, in the angiography-guided group (HR 1.25; 95% CI 0.97–1.60; p=0.08). Thus, the primary endpoint was numerically even less favorable with IVI.
By contrast, DKCRUSH VIII demonstrated a clear clinical benefit of IVUS in true complex bifurcation lesions treated with the DK-crush technique. In this study, the primary endpoint was also TVF, defined as a composite of cardiac death, target-vessel myocardial infarction, or clinically triggered target-vessel revascularization at 1 year. At 1 year, this endpoint occurred in 17 of 277 patients, 6.1%, in the IVUS group and in 41 of 278 patients, 14.7%, in the angiography-guided group (HR 0.40; 95% CI 0.23–0.71; p=0.002).
These data therefore argue against an undifferentiated assumption that IVI automatically leads to better outcomes in every complex PCI setting, but they do not argue against the fundamental value of IVI. Rather, they suggest that the benefit of IVI strongly depends on the respective clinical and procedural context.
In light of the 2024 ESC CCS guideline, these studies should therefore be understood more as a refinement than as a refutation of the existing evidence. The ESC assigns a Class I, Level of Evidence A recommendation to IVI with IVUS/OCT in anatomically complex lesions, including left main disease, true bifurcations, and long lesions. This recommendation is based on network meta-analyses by Kuno 2023 and Stone 2024, taking into account several randomized trials such as OCTOBER, RENOVATE-COMPLEX PCI, and ILUMIEN IV. In the guideline text, RENOVATE-COMPLEX PCI and OCTOBER are highlighted in particular as positive studies, whereas ILUMIEN IV was neutral with respect to its primary endpoint but showed fewer definite or probable stent thromboses. The underlying evidence is itself heterogeneous: while RENOVATE-COMPLEX PCI and OCTOBER primarily addressed anatomically complex lesions, ILUMIEN IV also defined complexity by the presence of clinical high-risk constellations.
The current discussion surrounding OPTIMAL and IVUS-CHIP suggests that the additional clinical benefit of IVI is highly context-dependent. A central argument is that both neutral studies were conducted in high-volume centers with very experienced IVUS operators. It is therefore plausible that some of the IVUS expertise acquired over years was “carried over” into the angiography-guided arm. In such a setting, the comparison is no longer between “optimal imaging” and “ordinary angiography,” but rather between imaging and an already “IVUS-calibrated” form of angiography. For this reason, the neutral results should not be uncritically extrapolated to routine care.
When analyzing the study design of OPTIMAL and IVUS-CHIP, it is notable that the use of preinterventional intravascular imaging, unlike in DKCRUSH VIII, where it was mandated as an obligatory procedural component, was merely recommended in the study protocol but not required. As a result, what AGIK considers essential planning imaging for the structured assessment of lesion morphology, lesion length, and the proximal and distal reference vessel diameter in the planned landing zone was not performed in more than one third of included patients in both neutral trials.
In addition, IVI appears to exert its benefit primarily when it actually guides the procedural strategy. This is evident in DKCRUSH VIII, where IVUS was not merely used as an adjunct but influenced technical decisions during a complex two-stent bifurcation procedure. By contrast, in OPTIMAL and IVUS-CHIP, the procedural approach with regard to lesion preparation, selection of stent and balloon sizes, and post-dilatation rate did not differ between the two groups. A neutral clinical effect is therefore not surprising when IVI provides information but does not substantially alter the interventional strategy.
In the IVUS-CHIP trial, the rate of stent thrombosis was lower with IVUS, which may be related to a lower rate of stent underexpansion, an important predictor of late stent thrombosis. This suggests that IVUS can indeed generate procedurally relevant advantages, but that these do not necessarily translate into an additional benefit in the primary composite endpoint in very experienced settings.
In summary, the new studies do not support fundamentally questioning the added value of IVI in complex PCI. Rather, they encourage a more targeted understanding of the benefit of IVI, particularly in cases with complex lesion morphology in which imaging leads to concrete changes in strategy, stent sizing, or result optimization, and in which relevant information would be lost without its use.
For clinical practice, this means that the ESC Class I, Level of Evidence A recommendation should not fundamentally be relativized, but it should be read in a more differentiated manner. The decisive question is not so much whether IVI is useful, but rather in which lesions, for which operators, and with what consequences for procedural implementation the additional benefit is greatest. Even the best intravascular imaging cannot improve the clinical outcomes of patients if the findings obtained do not lead to relevant diagnostic or therapeutic consequences for the strategy and performance of PCI.
