Correlations between fractional flow reserve and a novel non-hyperemic index: resting full-cycle ratio in patients with an ambiguous coronary artery stenosis

Abstract

Abstract Background Fractional flow reserve (FFR) measurement has been the gold standard for invasive assessment of coronary ischemia. Resting full cycle ratio (RFR) is a new non-hyperemic index used to define physiologic significance of coronary artery stenosis. However, there are limited data available to establish optimal cut-off value of RFR for decision making on revascularization. Aim The aim of our study was to assess optimal cut-off value of RFR at which to predict FFR of 0.8. Methods The RFR and FFR values were recorded during invasive coronary angiography in vessels with angiographic stenosis 40–70% according to visual assessment. Maximum hyperemia for FFR measurement was achieved with adenosine iv. infusion at 140 μg/kg/min. Left main disease, acute myocardial infarction and systolic left ventricular dysfunction (EF <40%) were the main exclusion criteria. Results We evaluated 332 vessels, including 189 (56.9%) left anterior descending arteries, 77 (23.2%) left circumflex arteries and 66 (19.9%) right coronary arteries. Median diameter stenosis as assed by QCA was 45% (IQR 40; 50). Median RFR and FFR values were 0.90 [IQR 0.85; 0.94] and 0.86 [IQR 0.81; 0.92] respectively, with significant correlation (p<0.001, Figure 1, panel A). Optimal cut-off value for RFR to detect FFR 0.80 was 0.90 with area under the curve of 90.3%, sensitivity of 81.4% and specificity 88.0% (Figure 1, panel B). Conclusions Our data confirm RFR cut-off value ≤0.90 as an optimal threshold to detect ischemic lesions with good sensitivity and specificity in comparison to FFR assessment. Further research is necessary to assess outcomes of RFR-guided revascularization strategy. Figure 1. RFR–FFR correlation and ROC analysis Funding Acknowledgement Type of funding source: Other. Main funding source(s): Jagiellonian University statutory grant