Ectopic coronary artery origin is not unusual, appearing in approximately 0.1%-1% of examinations. A wide variety of ectopic coronary origin anatomy can be demonstrated. Of these, only the ectopic anatomy resulting in passage of a coronary artery between the aorta and the pulmonary artery/right ventricular outflow tract are considered to be of so called "malignant" course. Other variants such as the left coronary or right coronary arising from the non coronary right cusp are considered benign. The commonest variation is the demonstrated, anomalous right coronary from the left coronary.
There is some controversy about this diagnosis, with some considering that this is sometimes incidental. However, it has been reported that up to quarter of young cardiac sudden death relates to such ectopic coronary artery origin. The likelihood that an ectopic malignant course coronary will result in symptomatology may relate to the angle of the origin of the vessel and whether this is partially intramural, possibly susceptible to more compression.
Other variations of the coronary anatomy that are concerning include the ectopic origin from the pulmonary artery. More peripheral branching arterial variations are usually not concerning such as intramural course (myocardial bridging). In myocardial bridging the coronary artery (usually the left anterior descending artery), passes temporarily into the myocardium. Despite mild narrowing this is rarely of clinical concern.