When an anomalous coronary artery takes an interarterial course — routing directly between the ascending aorta and the pulmonary artery (or RVOT) — it is classified as the “malignant” variant of anomalous origin from opposite sinus.
1 Clinical risk
This course carries an increased risk of myocardial ischemia, syncope, and sudden cardiac death (SCD) — particularly in young athletes during strenuous exertion.
It is the second most common cause of SCD in young athletes (after hypertrophic cardiomyopathy).
2 Pathophysiology
The increased risk is thought to be driven by the outward expansion of the aorta and pulmonary artery during cardiac stress, which physically squeezes and shears the anomalous vessel between them.
3 High-risk CTA features
Beyond simply passing between the great vessels, risk is considered exceptionally high if the CCTA demonstrates:
The proximal anomalous artery travels within the actual aortic wall itself before emerging.
The artery exits the aorta at a sharp angle, predisposing to dynamic compression.
The opening is compressed laterally rather than round — visible cross-sectionally on CCTA.
A malignant left coronary artery generally carries a graver prognosis than a malignant right.
4 Management
Symptomatic patients frequently require:
- Surgical unroofing — opens the intramural segment
- Coronary artery bypass grafting — bypasses the anomalous proximal course