Quantitative Flow Ratio Based on Murray Fractal Law: Accuracy of Single Versus Two Angiographic Views

Abstract

Background

Murray bifurcation fractal law–based quantitative flow ratio (QFR), namely, μQFR, is a novel method for the fast computation of fractional flow reserve (FFR) from a single angiographic view. We aimed to compare the diagnostic accuracy of computational QFR based on single vs 2 angiographic views in patients with intermediate coronary stenosis.

Methods

The algorithm of μQFR was extended to develop a Murray law–based 3-dimensional (3D) μQFR from 2 angiographic projections. Patients with both angiographic views acquired according to the protocol-specified recommended views in the FAVOR (Functional Diagnostic Accuracy of Quantitative Flow Ratio in Online Assessment of Coronary Stenosis) II China study were included. μQFR was computed separately from the first (μQFR1) and second (μQFR2) angiographic projections, whereas the 3D-μQFR was computed based on both projections, all blinded to FFR data. Hemodynamically significant coronary stenosis was defined by wire-based FFR of ≤0.80.

Results

Altogether, 280 vessels from 262 patients had 2 protocol-specified recommended angiographic views; μQFR1, μQFR2, and 3D-μQFR were successfully computed in all these vessels. The mean FFR was 0.82 ± 0.12. The vessel-level diagnostic accuracy for μQFR1, μQFR2, and 3D-μQFR to identify hemodynamically significant stenosis was 92.1% (95% CI, 89.0%-95.3%), 92.5% (95% CI, 89.4%-95.6%), and 93.2% (95% CI, 90.3%-96.2%), respectively, with similar areas under the receiver operating characteristic curve for μQFR1 (0.96, P < .001), μQFR2 (0.95, P < .001), and 3D-μQFR (0.95, P < .001). μQFR1 and μQFR2 had excellent correlation ( r = 0.95) and agreement (mean difference = 0.00 ± 0.03).

Conclusions

Computation of μQFR from a single angiographic view had comparably good diagnostic performance as 2-view 3D-μQFR in identifying hemodynamically significant coronary stenosis.

Central Illustration

Comparison of quantitative flow ratio based on Murray fractal law from single versus two angiographic views. Upper: An example of μQFR1, μQFR2, and 3D-μQFR computation. Two protocol-specified recommended angiographic projections for an intermediate lesion in LAD were acquired. μQFR1 and μQFR2 were computed based on the first and second angiographic projections, separately, while 3D-μQFR was computed based on both projections. The lumen contours of LAD and its side branches were delineated. Computed pressure pullbacks were co-registered with lumen profile. The computed value was 0.75, 0.72, and 0.76 for μQFR1, μQFR2, and 3D-μQFR at the asterisk positions. Lower: Diagnostic performance of μQFR1, μQFR2, and 3D-μQFR in a total of 280 vessels with two protocol-specified angiographic views. μQFR1, μQFR2, and 3D-μQFR have comparably good diagnostic performance in predicting physiologically significant stenosis using wire-based FFR as reference. FFR, fractional flow reserve; LAD, left anterior descending artery; μQFR, Murray law-based quantitative flow ratio; NPV, negative predictive value; PPV, positive predictive value; 2D, 2-dimensional; 3D, 3-dimensional.

Highlights

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  1- and 2-view Murray law-based quantitative flow ratio have comparable accuracy.

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  Both recommended views are reliable for Murray law-based quantitative flow ratio.

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  Murray law-based quantitative flow ratio can facilitate functional test in cath lab.