Recently, the New England Journal of Medicine (NEJM) published a FLAVOUR study led by Professor Wang Jianan of Zhejiang University Medical School and Professor Bon-Kwon Koo of Seoul National University Hospital.The results showed that the FFR was not inferior to IVUS in patients with moderate coronary artery stenosis (40%~70%) and the FFR was significantly lower in PCI group than IVUS group, reducing stent use and subsequent duplex antiplatelet therapy.
This is the first time NEJM has published the results of an international multicenter clinical trial initiated by a Chinese researcher as the lead author and first author.Wang Jianan is the main correspondence author of the paper, and his team member Professor Hu Xinyang is the co-author.
"This study is of direct practical significance for cardiologists and catheter rooms with only one of two devices, FFR or IVUS." In future studies, researchers will be able to further assess whether using FFR or IVUS alone is better than using both devices together and whether the results are applicable to higher-risk patients.
Can a device guide PCI be implemented
In 1977, the world's first percutaneous coronary angioplasty was successfully performed, opening the PCI era of coronary heart disease (CAD).It improves the quality of life and clinical prognosis of a large number of coronary heart disease patients in a minimally invasive, concise and efficient manner.
For PCI in patients with moderate coronary artery stenosis, cardiologists generally use FFR to assess the likelihood of ischemia and determine whether PCI is needed, while IVUS is used to select the appropriate stent size and position and size after stent implantation.Therefore, joint application of FFR and IVUS is considered the best method.
"FFR-based functional physiology tools and IVUS-based intraventricular imaging have been proven to be an effective complement to coronary angiography and significantly improve the clinical prognosis of patients with coronary heart disease.The clinical prognosis of coronary artery disease patients depends on a variety of factors, including coronary stenosis, plaque load and characteristics, functional physiology status and anatomical conditions.
But the reality is that in many medical institutions, catheter rooms are equipped with only one of FFR and IVUS.So, is it possible to guide PCI through only one of these devices?To answer this scientific question, Wang Jianan led the team to collaborate with 18 research centers in China and South Korea.
According to Wang, the prospective, randomized, open-label study included 1,682 patients with moderate coronary artery stenosis, head-to-head comparison of FFR and IVUS-guided PCI.Stent implantation was performed in 44.4% of patients in FFR group (838 patients) and 65.3% in IVUS group (844 patients).At two years, FFR was no worse than IVUS in terms of compounded major outcomes, all-cause death, myocardial infarction, or re-transfusion reconstruction.
FFR and IVUS are not good or bad
Previous studies, including FAME and FAME2, confirmed that FFR-guided PCI therapy can significantly reduce the incidence of cardiovascular events and have clear hygienic and economic value.
The IVUS-XPL and ULTIMATE studies demonstrated that the optimal PCI (minimum stent area, marginal plaque load) could improve the clinical prognosis and reduce the risk of re-transfusion.
However, both FFR and IVUS have limitations as technologies that reflect different levels.
Li Chenguang, deputy director of cardiology at Sun Yat-sen Hospital, Fudan University, said that the physiological evaluation represented by FFR could reflect the effect of fixed stenosis on hemodynamics and myocardial oxygen supply.
IVUS can display the cross-sectional images of the vessels, and then observe the structure of the vessels and determine the nature of the lesions. However, there are differences in the quality of the heart muscle.
For this reason, the 2018 European Society of Percutaneous Cardiovascular Intervention (ESCI) agreed that absolute minimum lumen area (MLA) is not recommended as the criterion for guiding blood flow reconstruction except for left trunk lesions.Therefore, it is not clear which method will bring better clinical benefits in the context of single tool selection.
In this context, FLAVOUR studies compared the value of FFR and IVUS in guiding coronary critical lesions.The results showed that there was no significant difference in POCO (all-cause death, myocardial infarction, blood circulation reconstruction) between the two groups under the guidance of FFR or IVUS.This suggests that FFR-guided blood reconstruction in patients with moderate coronary stenosis can achieve similar results as IVUS-guided "hard endpoints" in death, heart infarction, and so on, Wang said.
The results are similar to those of previous studies, which have confirmed that FFR guidance can effectively reduce the proportion of blood transfusion reconstruction and the number of stent implants.However, despite a significant decrease in either vascular or patient-level PCI, Seattle Angina scores showed no significant difference in 24-month follow-up, indicating the value of FFR as a physiological tool in assessing patients' ischemia.
Limited but epoch-making
There are limitations to any study.
First, the FLAVOUR study included only patients with critical coronary angiography lesions, and further research was needed on whether the two tools could be used as a guide for more severe disease classification.
Second, FFR and IVUS are the representative tools of physiology and imaging, but with the development of technology and the emergence of more physiological and imaging tools, such as functional assessment based on coronary angiography, IVUS and OCT.Can these tools combine the advantages of different dimensions to provide more comprehensive assessment information and raise expectations for clinicians?
At the same time, the effects of plaque vulnerability and local hemodynamics on treatment strategies were not considered.With the development of COMBINE (OCT-FFR), PROSPECT ABSORB, and the clinical application of near-infrared spectroscopy (NIRS), OCT, etc.
Admittedly, "FLAVOUR is the first study to compare the value of FFR and IVUS tools in coronary artery critical lesion blood flow reconstruction." said Ge Junbo.