What should be the role of fractional flow reserve measurement in patients undergoing coronary artery bypass grafting?

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  FFR cutoff value for arterial graft patency rate of 97% in the IMPAG trial.

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  Figure 1. Fractional flow reserve (FFR) physiological explanation. A, Example of a lesion with a 70% stenosis and a positive FFR of 0.7. B, Example of a lesion with a 70% stenosis with distal collateral and a negative FFR of 0.85. C, Example of a lesion with a 70% stenosis with a myocardial scar and a negative FFR of 0.85.

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  Figure 2. Fractional flow reserve (FFR) and competition flow in a moderate stenosis: Difference between saphenous and arterial graft. A, Example of a lesion with a 70% stenosis and a negative FFR of 0.89. B, Same example after a saphenous bypass. Absence of competition flow due to the pressure at the distal end of the vein of 99 mm Hg. C, Same example after an arterial bypass. High competition flow due to the drop of pressure at the distal end of the artery of 91 mm Hg. SVG, Saphenous vein graft.