Misconception of 'malignant' and 'scissor-like compression' of interarterial course in anomalous aortic origin of a coronary artery: a case series

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 with that in the coronary system. However, data supporting or refuting this belief under stress conditions are lacking.Case summary Three cases of right AAOCA with interarterial/intramural courses (52, 66, and 51 years old) 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. 5.71-3.47 mm2, 5.88-4.00 mm2, and 5.85-4.06 mm2) under stress conditions with heart rates of 130, 140, and 150 b.p.m., respectively. Pulmonary artery pressure (PAP) increased from rest {s/d (m) [systolic/diastolic (mean)] 22/11 (15), 15/2 (5), and 24/6 (14) mmHg} to stress [s/d (m) 47/24 (36), 30/3 (11), and 36/22 (24) mmHg] and remained below aortic peak pressure (blood pressure, BP) rest [s/d (m) 116/64 (91), 94/48 (71), 99/53 and (62) mmHg]; BP stress [s/d (m) 142/63 (80), 123/63 (88), and 86/46 (62) mmHg]; coronary pressure (CoP) rest [s/d (m) 100/59 (80), 80/45 (62), and 83/47 (63) mmHg]; and CoP stress [s/d (m) 95/60 (69),101/54 (72), and 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 haemodynamic significance.