In the treatment of coronary artery disease (CAD), fractional flow reserve (FFR) can be performed during coronary angiography to evaluate the need for percutaneous coronary intervention (PCI).¹ Nevertheless, the efficacy of wire-based FFR is constrained by its practical limitations.^1,2 Computational pressure-flow dynamics-derived FFR (caFFR) is a novel technique that negates the inherent limitations of wire-based FFR.^1,2 To evaluate the per-vessel prognostic value of caFFR, researchers from the Department of Medicine, School of Clinical Medicine, LKS Faculty of Medicine of the University of Hong Kong (HKUMed) conducted a local population-based retrospective study.

FFR is often utilized as an evaluation tool for detecting inducible myocardial ischemia during coronary angiography in patients with CAD.¹ The FAME 2 trial demonstrated FFR-assisted PCI’s notable efficacy in improving the clinical outcomes of patients with stable CAD and functionally significant stenoses (defined as FFR≤0.8) when it was performed in combination with the best available medical therapy.³ However, conventional wire-based FFR requires  pharmacology-induced hyperemia, which may lead to patient discomfort and an increased risk of coronary dissection and morbidity from arrhythmia.2 As a result, wire-based FFR has been clinically underutilized, with >80% of patients having intermediate obstructive coronary lesions not being assessed for FFR.¹

The emergence of caFFR, a novel FFR technique that utilizes invasive aortic pressure accompanied by computational fluid dynamics (CFD) during the time of angiography, offers solutions to overcome the limitations of wire-based FFR and serves as a reliable alternative option for conducting FFR in patients with stable CAD.^1,2 Hence, a retrospective study was conducted to investigate the long-term clinical benefits derived from caFFR categorization of ischemic status in patients with stable CAD.¹

In this study, 2,608 adult stable CAD patients who underwent coronary angiography between 2014 and 2016 were enrolled.¹ Upon further exclusion, 3,329 vessels from 1,308 patients who underwent caFFR were included and categorized into 3 cohorts for subsequent analysis.¹ The ischemic cohort consisted of 926 ischemic vessels (defined as FFR≤0.8), with 76.5% of them being treated with PCI (PCI+) and 23.5% of them did not receive PCI (PCI-).¹  On the other hand, the non-ischemic cohort consisted of 2,403 non-ischemic vessels (defined as FFR >0.8), with 19.2% and 80.8% of them belonging to PCI+ and PCI- groups, respectively.¹ Lastly, the adherent-to-caFFR cohort recategorized all vessels (n=3,329) into the adherent group (PCI+ ischemic vessels & PCI- non-ischemic vessels) (n=2,649) and the non-adherent group (PCI- ischemic vessels & PCI+ non-ischemic vessels) (n=680).¹ The primary outcome of this study was the vessel-oriented composite endpoint (VOCE) at  3 years, which encompassed vessel-related cardiovascular mortality, non-fatal myocardial infarction (MI), and repeat revascularization.¹

The results from the analysis after multivariable adjustment reflected significant improvements in VOCE facilitated by caFFR-assisted PCI in the ischemic and adherent-to-caFFR cohorts after 3 years.¹ In the ischemic cohort, the PCI+ group exhibited a 56% risk reduction of VOCE compared to the PCI- group (HR=0.44; 95% CI: 0.26-0.74;  p=0.002).¹ Similarly, a 31% risk reduction in VOCE was also associated with the adherent group when compared with its  non-adherent counterpart in the adherent-to-caFFR cohort  (HR=0.69; 95% CI: 0.48-0.98; p=0.039).¹ However, no significant difference in the risk of VOCE was observed between the PCI+ and PCI- groups in the non-ischemic cohort (caFFR>0.80) (HR=1.04; 95% CI: 0.62-1.74; p=0.888).¹

To conclude, with the assistance of caFFR, PCI was shown to induce a significantly lower incidence of VOCE at 3 years among ischemic lesions (caFFR ≤0.8), while the incidence of VOCE at 3 years among non-ischemic lesions (caFFR>0.8) remained consistent regardless of PCI treatment, indicating revascularization in non-ischemic lesions does not provide clinical benefit and should be avoided.¹ The findings of this study also illustrated the prognostic value of caFFR in determining the ischemic status of vessels, evidenced by the significantly lower risk of VOCE and more desirable clinical outcomes of adherent-to-caFFR vessels.¹ This reinforces the role of caFFR in providing clinically meaningful and durable prognostic information during future decision-making processes about revascularization in patients with CAD.¹