Fractional Flow Reserve/Instantaneous Wave-Free Ratio Discordance in Angiographically Intermediate Coronary Stenoses

Figures

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  Figure 1. Distribution of FFR, iFR, and CFR Values for Stenosed Vessels Frequency histograms reveal unimodal data distributions of fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and coronary flow reserve (CFR) values in the stenosed vessel groups. The solid red line indicates the median value. The solid black line indicates the mean value.

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  Figure 2. Scatter Plot Showing the Relationship Between FFR and iFR The black line represents the line of best fit. The curve is fitted by second-order polynomial. The gray lines represent the respective cutoff values for FFR (≤0.80) and iFR (≤0.89). Concordant cases are colored blue, discordant cases are colored orange. Abbreviations as in Figure 1.

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  Figure 3. Boxplot Comparisons of Baseline and Hyperemic Coronary Flow Velocity The horizontal black line indicates the median value. The box indicates the interquartile range and the whiskers indicate the range of values. FFR+/iFR+ (n = 108) cases are colored red. FFR–/iFR+ (n = 28) and FFR+/iFR– (n = 22) discordant cases are colored orange. FFR–/iFR– (n = 208) cases are colored light green. Unobstructed reference vessel (n = 201) cases are colored dark green. (A) Baseline coronary flow velocity was similar across all groups. (B) Hyperemic coronary flow velocity was similar in FFR+/iFR+ and FFR–/iFR+ groups. Hyperemic coronary flow velocity was similar in FFR+/iFR–, FFR–/iFR– and unobstructed reference vessel groups. Abbreviations as in Figure 1.

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  Central Illustration. Boxplot Comparisons of CFR The horizontal black line indicates the median value. The box indicates the interquartile range, and the whiskers indicate the range of values. Coronary flow reserve (CFR) values ≤2 and >2 are colored pink and green, respectively. CFR was significantly higher in the fractional flow reserve (FFR) positive and instantaneous wave-free ratio (iFR) negative versus FFR–/iFR+ discordant groups (and similar to FFR–/iFR– and unobstructed reference vessel groups).

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  Figure 4. FFR+/iFR– Discordance Attributed to High CFR: Clinical Case The coronary angiogram image displays a proximal circumflex stenosis. Quantitative coronary angiography derived percentage diameter stenosis, area stenosis, and minimal lumen diameter were 62%, 85%, and 1.20 mm, respectively. Invasive pressure-based coronary physiology assessment revealed discordant iFR (negative) and FFR (positive) results. Upon measuring combined coronary pressure-and-flow data, the FFR+/iFR– discordant result can be attributed to high CFR. Abbreviations as in Figure 1.