Scatter plot showing relationship between angiographic stenosis grade and FFR for all vessels by 3D-QCA (A) and 2D-QCA (B). The dotted line represents FFR =0.80. Numbers in each category: (A) <40%, n=108; 40% to 49.9%, n=284; 50% to 59.9%, n=178; 60% to 69.9%, n=60; ≥70%, n=15. In lesions graded <40% DS, FFR ≤0.80 was present in 5.6%, thus in 5.6% of stenoses <40% DS, FFR indicated physiologically significant lesion. In lesions graded ≥70% DS, FFR ≤0.80 was present in 93.3%, thus in 6.7% of stenoses ≥70% DS, FFR indicated physiologically non-significant lesion. In lesions graded between 40% to 69.9% DS, FFR ≤0.80 was present in 38.9%. (B) <40%, n=194; 40% to 49.9%, n=238; 50% to 59.9%, n=144; 60% to 69.9%, n=58; ≥70%, n=11. In lesions graded <40% DS, FFR ≤0.80 was present in 21.6%, thus in 21.6% of stenoses <40% DS, FFR indicated physiologically significant lesion. In lesions graded ≥70% DS, FFR ≤0.80 was present in 72.7%, thus in 27.3% of stenoses ≥70% DS, FFR indicated physiologically non-significant lesion. In lesions graded between 40% to 69.9% DS, FFR ≤0.80 was present in 39.3%. 2D-QCA, 2-dimensional quantitative coronary angiography; 3D-QCA, 3-dimensional quantitative coronary angiography; DS%, percent diameter stenosis; FFR, fractional flow reserve.