An 11-Year-Old Athlete With Dynamic Stenosis of Coronary Artery Anomaly With Normal FFR-Dobutamine But Abnormal iFR-Dobutamine

Figures

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  Visual Summary. R-AAOCA With Interarterial and Intramural Course in an 11-Year-Old Symptomatic Basketball Player (Top Left, blue background) Patient-specific invasive findings at rest demonstrate a Pd/Pa ratio of 0.96 and an iFR of 0.96. Diastolic IVUS reveals a vessel with a minimal lumen area of 6.6 mm2 during diastole (distal reference: 14.6 mm2), with the 3D reconstruction coregistered to the CCTA. The vessel displays significant geometrical changes between diastole and systole. (Bottom Left, red background) Under dobutamine stress, invasive findings show a hemodynamically nonsignificant FFRDobutamine of 0.85, contrasted by a significantly lower iFRDobutamine of 0.72. IVUS shows a marked reduction in lumen area to 3.7 mm2 (distal reference: 15.3 mm2). (Right Side, red/blue striped background) Comparative analysis from rest to stress indicates that luminal deformation is significantly more pronounced during the diastolic phase than the systolic phase. This phase-specific dynamic likely explains the discrepancy between the cycle-averaged FFRDobutamine and the diastolic-specific iFRDobutamine. 3D = three-dimensional; CCTA = coronary computed tomography angiography; FFR = fractional flow…

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  Figure 1. CCTA Images (Left) Intramural course length of 11.4 mm, with the interluminal space between the aorta and the coronary artery highlighted in red and the pulmonary artery in blue. (Right) Ostial lumen area of 4.36 mm2, with a major axis of 3.3 mm and a minor axis of 1.4 mm. The pulmonary artery is again shown in blue. CCTA = coronary computed tomography angiography.

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  Figure 2. Rb-PET/CT During Dobutamine Stress (Left) Rb-PET/CT stress perfusion map during dobutamine-atropine volume challenge showing a reversible perfusion defect in the inferior myocardium (AHA segments 4 and 9), corresponding to ∼5% of left ventricular mass. (Right) Matched rest perfusion demonstrating full reversibility. Images are shown in short-axis orientation with the same intensity scale. AHA = American Heart Association; Rb-PET/CT = rubidium positron emission tomography/computed tomography.

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  Figure 3. IVUS Ostial Cross-Sections (Diastole and Systole) at Rest, During Adenosine, and During Dobutamine Stress (First Column) At rest: diastolic lumen area 7.6 mm2 and systolic lumen area 4.6 mm2 (reference area: 14.6 mm2). (Second Column) Adenosine: diastolic 7.0 mm2 and systolic 4.5 mm2 (reference area: 14.0 mm2). (Third Column) Dobutamine volume challenge (stress ostium): diastolic 3.7 mm2 and systolic 3.1 mm2. (Fourth Column) Dobutamine volume challenge (stress ostium): diastolic 3.1 mm2 and systolic 2.7 mm2. Note the marked reduction in diastolic lumen area during stress compared with at rest (7.6 → 3.7 mm2). Panels are aligned to the same scale. Lumen contours are in green, minor axis is in yellow, and the major axis is in blue. IVUS = intravascular ultrasound; MLA = minimal lumen area.

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  Figure 4. Pd/Pa, FFR, and iFR During Rest and Adenosine-Dobutamine Stress (Left) Pd/Pa and iFR (range displayed by orange bars in all images, while Pd/Pa or FFR is in yellow) during resting conditions, showing no discrepancies (both 0.96). (Right) During dobutamine stress there was a clear difference, with FFR of 0.85 and iFR of 0.72. FFR = fractional flow reserve; iFR = instantaneous wave-free ratio; MLA = minimal lumen area; Pd/Pa = distal coronary artery pressure/aortic pressure.

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  Figure 5. 3-Dimensional Reconstruction of IVUS Images and Alignment With CCTA Images (Left) Diastolic IVUS reconstruction registered to the CCTA-derived centerline, showing the intramural course. (Bottom Inset) Difference map (diastole minus systole) demonstrating pulsatile lumen deformation along the intramural segment. (Right) Diastolic reconstruction during dobutamine stress showing marked lumen reduction throughout the intramural course (example midpoint area: 11.4 mm2 at rest → 3.0 mm2 during stress). CCTA = coronary computed tomography angiography; IVUS = intravascular ultrasound; MLA = minimal lumen area.

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  Figure 6. Anatomical Relation of the Anomalous Right Coronary Artery to the Pulmonary Valve and Aortic Commissures Systolic IVUS-based geometry (reconstructed during dobutamine stress) aligned to CCTA anatomy, illustrating the vessel course relative to the pulmonary (in orange) and aortic valve planes (in gray). A focal 5-mm segment that runs posterior to the pulmonary valve could account for the observed 5 mm increase in apparent intramural length during stress versus rest. CCTA = coronary computed tomography angiography; IVUS = Intravascular ultrasound.