Robust association between changes in coronary flow capacity following PCI and vessel-oriented outcomes
Authors: Hamaya R , Yonetsu T , Ueno H , Hoshino M , Sugiyama T , Sasano T , Kakuta T 
Published: October 2022

Abstract

Backgrounds
While trials show a comparative effectiveness of percutaneous coronary intervention (PCI) against medical therapy with respect to patient outcomes, deferring all elective PCI might be too simplistic, given the prognostic benefit differential according to several factors. Coronary flow capacity (CFC) is a potentially useful coronary flow (CF)-related physiologic marker of ischemia for guiding PCI indication [1,2]. However, the physiological/prognostic mechanics of the CFC guidance, which could be assessed by CFC changes following PCI, have not been investigated.

Objectives
To assess the determinants and prognostic implication of the change in the CFC status following PCI.

Methods
From a single center registry, 450 patients with chronic coronary syndrome (CCS) who underwent fractional flow reserve (FFR)-guided PCI with pre-/post-PCI coronary physiological assessments by thermodilution-method were included. CFC status was defined as follows [1]; normal CFC as CFR ≥2.80 with hyperemic CF (hCF) ≥3.70; mildly reduced CFC as CFR &lt;2.80 and ≥2.10, combined with hCF &lt;3.70 and ≥2.56; moderately reduced CFC as CFR &lt;2.10 and ≥1.70, and 1/Tmn &lt;2.56 and ≤2.00; and severely reduced CFC otherwise (CFR &lt;1.70 and hCF &lt;2.00). Associations between PCI-related changes in thermodilution method-derived CFC categories and incident target vessel failure (TVF) during a median follow-up of 4.3 (IQR: 2.5, 6.9) years were assessed by multivariate COX proportional hazard models.

Results
The mean (SD) age was 67.1 (10.0) years and there were 75 (16.7%) women. There were no differences in survival according to pre-PCI CFC status (P for linear trends = 0.22). Compared with patients showing no change in CFC categories after PCI, patients with category worsened, +1, +2, and +3 category improved had the hazard ratio (95% CI) for incident TVF of 2.27 (0.95, 5.43), 0.85 (0.33, 2.22), 0.45 (0.12, 1.63), and 0.14 (0.016, 1.30), respectively (P for linear trends = 0.0017). The relevant Kaplan-Meier curves were illustrated in the Figure, which highlights a best survival in those with +3 categories improvement (severely reduced to normal CFC) and worst in worsened CFC. After adjustment for confounders, one additional improvement in CFC status was associated with 0.61 (0.45, 0.83) times the hazard of TVF. CFC changes ≥3 categories were largely predicted by pre-PCI CFC with area under the curve of 0.94 (95% CI: 0.93, 0.96), and 48.6% of the variability of continuous CFC changes in ranks was explained solely by pre-PCI CFC, while only 12.4% by FFR.

Conclusion
CFC improvement following PCI, which was largely determined by the pre-PCI CFC status, was associated with lower risk of incident TVF in patients with CCS who underwent PCI. Therefore, CFC changes provide a mechanistic explanation on a potential favorable effect of PCI on reducing vessel-oriented outcome in lesions with reduced CFC and low FFR.

Funding Acknowledgement
Type of funding sources: None.