Be Open-Minded ― Recognize an Invisible Gorilla and Let Go of Linus’ Security Blanket ―
Article ID: CJ-23-0245
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Article ID: CJ-23-0245
In this issue of the Journal, Yamamoto et al1 report the effect of optimal intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) compared with standard PCI. They retrospectively compared two cohorts (2011–2013 and 2019–2021) using propensity score-matching. However, it would be difficult to truly compare the effect of optimal IVUS-guided PCI on any coronary revascularization (a component of the primary endpoint) because clinical practice methodologies were quite different between the cohorts. Following a report demonstrating that performing follow-up invasive coronary angiography (CAG) added to the rate of repeat PCI without clinical benefit,2 routine follow-up CAG is not recommended in Japan.3 Supporting that, the insurance coverage/reimbursement requirement was also changed in 2018 in Japan. In general, proof of functional ischemia should be completed prior to PCI. Moreover, there was no difference in the frequency of OPTIVUS criteria having been met in all stented lesions between the groups (reference 1, table 1, 37.3% vs. 40.3%). Given no difference in clinically driven coronary revascularization, it is likely that non-clinically driven coronary revascularization was reduced by clinical practice change (10.5% vs. 0%), rather than by optimal IVUS-guidance per se. It seems to be an “Invisible Gorilla” situation.4 To examine the effect of optimal IVUS-guidance, 2 cohorts from the same period after 2018 should have been compared. Otherwise, clinically-driven coronary revascularization should have been chosen as a component, as in major randomized controlled trials (RCTs),5,6 rather than any coronary revascularization.
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The penetration of IVUS-guided PCI in real-world practice varies among countries (Figure). The use of IVUS-guided PCI is most common in Japan (≈80%), followed by Korea and Germany (≈20%), whereas the USA and Italy have rates of ≈5%.7 This could partially be due to differences in practice guidelines. Although the recommendation class/evidence level is 2a/B-R or IIa/B in the USA and Europe,8,9 a stronger recommendation class with higher evidence level (I/A) is suggested for left main trunk, chronic total occlusion, and diffuse lesions in Japan.10 Although most RCTs to compare IVUS-guided vs. angiography-guided DES implantation have been conducted in East Asia (Korea/China), no specific RCT has been conducted in Japan.
Penetration of intravascular ultrasound-guided percutaneous coronary intervention in real-world practice.
Due to the many factors that differ substantially between countries, comparative data analysis should be made with caution.11 Moreover, it could be said that IVUS-guidance is overused in Japan (80%) and underused in the USA (5%). In Japan, IVUS seems to be routinely used irrespective of lesion complexity and the interventionalist’s skills. Routine IVUS-guidance should allow the users to learn both lesion morphology in more detail and the optimal endpoint for PCI12 through comparing angiographic and IVUS tomographic images (i.e., learning effect). Skilled IVUS users could interpret angiographic images more accurately even without IVUS images, which may lead to better clinical outcomes.13 In the present study, it is possible that the learning effect of routine IVUS-guidance would result in no significant difference in the frequency of OPTIVUS criteria being met in all stented lesions between the groups (reference 1, table 1). Therefore, it is reasonable for junior interventionalists to use IVUS-guidance, even for simple lesions, whereas skilled IVUS users may not need IVUS-guidance for most simple lesions thanks to the learning effect. For skilled IVUS users, IVUS-guidance for simple lesions would be akin to Linus’ security blanket (i.e., something that gives a person a sense of protection and/or a feeling of security). It would be interesting to examine the non-inferiority of angiography-guided PCI by skilled interventionalists for simple lesions in Japan.14 Given the distress in the Japanese insurance system, selected use should be considered according to the interventionalist’s skills/experience in IVUS as well as lesion complexity.15
We do congratulate Yamamoto et al for doing this challenging investigation. A good study evokes important questions leading to advances in science and clinical practice.
We gratefully acknowledge Y. Honda, MD, at the Center for Research in Cardiovascular Interventions, Stanford University Medical Center, Stanford, California, USA. We also thank Heidi N. Bonneau, RN, MS, CCA, for her review of the manuscript.
None.
The authors declare that there are no conflicts of interest.
