Abstract
Quantitative flow ratio (QFR) is a recently proposed angiographic index that allows to assess the pressure loss in coronary arteries in a similar fashion as the fractional flow reserve (FFR). The purpose of this study was to evaluate the diagnostic performance of QFR as compared to FFR, in a Latin-American population of patients with suspected ischaemic heart disease. QFR was retrospectively derived from coronary angiograms. The association, diagnostic performance, and continuous agreement of fixed-flow QFR (fQFR) and contrast-flow QFR (cQFR) with FFR was assessed by continuous and dichotomous methods. 90 vessels form 66 patients were finally included. The study comprised coronary stenoses of intermediate severity, both angiographically (diameter stenosis: 46.6 ± 12.8%) and physiologically [median FFR = 0.83 (quartile 1-3, 0.76-0.89)]. The correlation of FFR with both fQFR [ρ = 0.841, (95% CI 0.767 to 0.893), p < 0.001] and cQFR [ρ = 0.833, (95% CI 0.755 to 0.887), p < 0.001] was strong. The diagnostic performance of cQFR was good [area under the ROC curve of 0.92 (95% CI 0.86 to 0.97, p < 0.001)], with 0.80 as the optimal cQFR cut-off against FFR ≤ 0.80. This 0.80 cQFR cut-off classified correctly 83.3% of total stenoses, with a sensitivity of 85.2% and specificity of 80.6%. QFR was strongly associated with FFR and exhibited a high diagnostic performance in this Latin-American population.
Highlights
In patients with symptoms compatible with ischaemic heart disease (IHD), clinical guidelines recommend invasive coronary angiography (ICA) complemented by physiological guidance with pressure wire-derived fractional flow reserve (FFR), if symptoms are responding poorly to medical treatment and revascularization is being considered.[1]
The correlation of FFR with both flow QFR (fQFR) [ρ=0.841, p
The diagnostic performance of cQFR was numerically better [area under the receiver-operating characteristic (ROC) curve of 0.92], with 0.80 as the optimal cQFR cut-off against FFR≤0.80
Summary
In patients with symptoms compatible with ischaemic heart disease (IHD), clinical guidelines recommend invasive coronary angiography (ICA) complemented by physiological guidance with pressure wire-derived fractional flow reserve (FFR), if symptoms are responding poorly to medical treatment and revascularization is being considered.[1] The worldwide use of coronary physiology indices like FFR, remains low,[2] in developing regions, like Latin-America. Quantitative flow ratio (QFR®; QAngio XA 3D, Medis Medical Imaging Systems, Leiden, The Netherlands) is a novel computational software that allows to calculate FFR from ICA without the need of pressure wires.[3] QFR has been extensively investigated and has exhibited robust diagnostic features in European, Asian, and US- populations.[4] Supported on these, QFR-based revascularization strategies are currently being tested in large randomized clinical trials. The clinical usefulness of QFR in populations from LatinAmerica, still, has not been reported. Deriving data from our region is important to correctly frame results of ongoing QFR-clinical trials
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