Differential impact of coronary revascularization on long-term clinical outcome according to coronary flow characteristics: analysis of the international ILIAS registry
Authors: Hamaya R , Hoef T , Lee J , Kakuta T 
Published: October 2022

Abstract

Backgrounds
Coronary pressure indices such as fractional flow reserve (FFR) are standard in guiding elective revascularization. However, considering additional coronary flow parameters could further individualize and optimize the decision on revascularization, especially in terms of the impact on prognosis. We aimed to investigate the potentially differential prognostic associations of elective PCI according to coronary flow properties represented by coronary flow reserve (CFR), coronary flow capacity (CFC) and baseline CFC (bCFC).

Methods
From the Inclusive invasive physiological assessment in angina syndromes (ILIAS) registry composed of 16 hospitals globally from 7 countries, patients with obstructive coronary artery disease who underwent invasive coronary physiological assessment were included (N=2370 vessels). We assessed effect measure modifications of the association of PCI and 5-year target vessel failure (TVF) according to CFR, CFC and bCFC either assessed by Doppler-technique or thermodilution-method in three models: conditional logistic regression, marginal structural model, and COX proportional hazard model. Reduced CFR, CFC and bCFC were defined as CFR&lt;2.1, CFR&lt;2.1 with hyperemic average peak flow velocity (APV)&lt;33.8 cm/s, and CFR&lt;2.1 with baseline APV&gt;17.0 cm/s in Doppler-technique, respectively (Figure 1), and the corresponding percentiles in thermodilution-methods. All models were adjusted for FFR, the interaction between PCI and FFR, and other confounders.

Results
The mean age of the population was 63.3 years and there were 1322 (73.6%) males. Median FFR was 0.85 and PCI was performed in 600 (25.3%) vessels. Reduced CFR, CFC, and abnormal bCFC were defined in 988 (41.7%), 542 (22.9%), and 600 (25.3%) vessels, respectively. There were little overlaps in vessels with reduced CFC and abnormal bCFC. In univariate analyses, vessels with reduced CFC had worse outcomes compared with those with normal CFC if deferred (13.4% vs. 6.6%), whereas reduced CFC was associated with better prognosis if treated by PCI (9.5% vs. 11.3%). Significant effect measure modifications were observed by CFC either in odds ratio (P=0.0018), additive (P=0.029), and hazard ratio scale (P=0.0002) (Figure 2). Vessels with reduced CFC had, compared with those with normal CFC, higher adjusted absolute risk of 5-year TVF by 5.9 [0.1, 12] percent if deferred, but lower risk by 1.8 [−1.7, 5.3] percent if treated by PCI. CFR and bCFC were not significant effect modifiers in any scales. Similar associations were observed in per-patient analyses, whereas the findings were less robust.

Conclusions
We observed a beneficial impact of PCI on absolute risk of 5-year clinical outcomes in vessels with reduced CFC, and a detrimental effect in those with normal CFC. CFR and bCFC were not robust effect modifiers of PCI. Therefore, CFC, combined with FFR, could be potentially used to optimize the patient selection for elective PCI treatment.

Funding Acknowledgement
Type of funding sources: None.