Abstract Background The notion that the “interarterial” segment of anomalous aortic origin of a coronary artery (AAOCA) is ‘malignant’ and ‘scissor-like’ compressed between the aorta and pulmonary artery (PA) is debated, owing to the lower pressure in the pulmonary system compared to that in the coronary system. However, data supporting or refuting this belief under stress conditions are lacking. Case presentation Three cases of right (R)-AAOCA with interarterial/intramural courses (52, 66, 51y/o) were assessed. Invasively measured Fractional Flow Reserve (FFR) under dobutamine was 0.85, 0.82 and 0.81, respectively. Intravascular ultrasound illustrated lateral vessel compression of the intramural course with a decrease of minimal lumen area (MLA) (i.e. 5.71mm2 to 3.47mm2, 5.88mm2 to 4.00mm2 and 5.85mm2 to 4.06mm2) under stress conditions with heart rates of 130, 140 and 150/min respectively. Pulmonary artery pressure (PAP) increased from rest [s/d(m) 22/11(15), 15/2 (5), 24/6(14)mmHg, to stress s/d(m) 47/24(36), 30/3(11), 36/22(24)mmHg], and remained below aortic peak pressure (BP) rest [s/d(m) 116/64(91), 94/48(71), 99/53(62)mmHg]; BP stress [s/d(m) 142/63(80), 123/63(88), 86/46(62)mmHg]; and coronary pressure (CoP) rest [s/d(m) 100/59(80), 80/45(62), 83/47(63)mmHg]; CoP stress [s/d(m) 95/60(69),101/54 (72), 70/32(50)mmHg]. Conclusion This case series challenges the assumption that the interarterial segment of AAOCA is scissor-like compressed by both the aorta and PA. The decrease in MLA and FFR under stress is due to the aorta’s unidirectional lateral compression on the intramural segment. Additionally, the term ‘malignant’ should not be universally applied to all AAOCA cases with an interarterial course, as not all result in hemodynamic significance.