Background Anomalous aortic origin of a right coronary artery (R-AAOCA) can cause stress-induced ischemia owing to dynamic stenosis of the intramural course. While fractional flow reserve during dobutamine challenge (FFRDobutamine) is the reference standard for hemodynamic assessment, specific scenarios favoring instantaneous wave-free ratio (iFR) over FFR remain unclear. Case Summary An 11-year-old male competitive basketball athlete with exertional angina and R-AAOCA underwent invasive angiography. Intravascular ultrasound showed a reduction in the intramural coronary lumen cross-sectional areafrom rest to dobutamine stress (from 4.6 to 3.1 mm2 in systole; from 7.6 to 3.7 mm2 in diastole), while FFRDobutamine was 0.85 and iFRDobutamine was 0.72. Discussion The patient's iFRDobutamine matched geometrical changes and clinical presentation, while his FFRDobutamine underestimated ischemia. Take-home Message In the case of predominant diastolic, stress-induced intramural deformation of the R-AAOCA vessel, iFRDobutamine-targeting diastolic stress-pressure ratio-may be preferred over FFRDobutamine, as the latter may miss ischemia given its cardiac cycle-averaged hyperemic calculations.
