Correlation and consistency between resting full-cycle ratio and fractional flow reserve in assessing coronary artery function in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome: a retrospective observational study.

ABSTRACT

OBJECTIVE: The study aimed to investigate the correlation and consistency between resting full-cycle ratio (RFR) and fractional flow reserve (FFR) in functional assessment of coronary arteries in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). DESIGN: Retrospective study. SETTING: A single-centre study in China. PARTICIPANTS: A total of 292 diseased vessels of 226 Chinese patients with NSTE-ACS at Cangzhou Central Hospital of Hebei Medical University from September 2021 to June 2023 were included. METHODS: The correlation between RFR and FFR, resting ratio of distal coronary artery pressure (Pd) to aortic pressure (Pa) and FFR were analysed by using Person correlation, and the consistency between RFR and FFR, resting Pd/Pa and FFR were assessed by Bland-Altman test. The diagnostic values of RFR and resting Pd/Pa for predicting FFR≤0.80 were evaluated according to the receiver operating characteristic (ROC) curves. RESULTS: RFR and resting Pd/Pa were significantly correlated with FFR, and correlation coefficients were 0.787 (p<0.001) and 0.765 (p<0.001), respectively. We found no significant differences between RFR and FFR or between resting Pd/Pa and FFR. The areas under the ROC curves for predicting FFR≤0.80 were 0.883 (p<0.001) for RFR and 0.858 (p<0.001) for resting Pd/Pa, and the optimal critical values were 0.91 for RFR and 0.93 for resting Pd/Pa. The accuracy, sensitivity, specificity and positive and negative predictive values of RFR≤0.91 for predicting FFR≤0.80 were 79.1%, 84.0%, 76.6%, 65.1% and 90.2%, respectively. CONCLUSION: The current study suggests that RFR exhibits a good correlation and consistency with FFR in patients with NSTE-ACS. RFR is expected to significantly enhance the application of coronary artery functional assessment in clinical practice, thereby providing patients with more precise revascularisation strategies.