The embryogenesis of the coronary vasculature begins with sinusoids located in the interventricular and atrioventricular sulci. The connection of the coronary arteries to the aorta occurs after the development of intracardiac septa and arterial trunks (aorta and trunk of the pulmonary artery). There is first a separation of the aortic and pulmonary rings (initially joined) with formation of the sub-pulmonary septum which distances the developing coronary arteries, and of the sub-aortic septum which attracts them. Thus, the connection of the coronaries to the aorta is made by penetration into the right anterior and left anterior aortic sinuses, also called coronary sinuses. This is why we prefer to use the term anomaly of coronary connection rather than coronary birth [1]. It is therefore concluded that the position of the arterial trunks and their relationship to each other play an important role in the connection of the coronary arteries. In congenital heart disease with malformation of the arterial trunks, ANOCORs are frequent [2], whereas in the case of our patient, in the absence of structural congenital heart disease, the precise mechanism of the abnormal connection of the coronary artery remains unknown.

The ectopic coronary artery connected to the contralateral artery is defined by the existence of a single coronary ostium connected in the usual sinus with a non-ectopic coronary artery following its usual course at the level of the cardiac structures, and an ectopic artery (coronary left or right coronary) generally connected to the first millimeters of the contralateral artery (Figure 7) or one of its branches. We come to understand that the ectopic coronary artery necessarily presents an abnormal initial course (distance between the connection with the non-ectopic artery and the area where the ectopic artery joins its usual myocardial territory) of variable length related to the arterial trunks and to the adjacent cardiac structures allowing it to reach its myocardial territory which is irrigated by the anterograde pathway. There are four possible pathways (Figure 8) which are: a) a pre-infundibular course, b) a retro-infundibular course which goes along the pulmonary infundibulum and the sub-aortic septum, c) a pre-aortic course, or d ) a retro aortic course.

The course of the ectopic artery is juxta mural to the aorta (very close to the aorta but without a common media) in the case of a pre-aortic or retro-aortic course, and could not theoretically be intra-mural (with a common media to the aorta and to the ectopic artery) in the case of an ectopic coronary artery connected to the contralateral artery.

This is a rare congenital anomaly but whose angiographic prevalence remains difficult to determine due to the scarcity of studies that distinguish ectopic connections with the contralateral artery from the single coronary artery. The only study that clearly differentiates them finds a prevalence of 0.046% for ectopic coronary artery with a higher frequency of left ectopic coronary artery than right ectopic coronary artery [3].

The coronary angiography generally makes it easy to diagnose an ectopic coronary artery connected to the contralateral artery, but still does not give good precision on the initial ectopic course with a risk of interpretation errors or even confusion, especially for the distinction between a pre-aortic course and a retro-infundibular course.

It is the cross-sectional imaging, and more particularly the CT scan, which has become the gold standard in this field for the diagnosis and the precision of the initial course, especially to distinguish a pre-aortic course from a retro infundibular course. During a pre-aortic course, the ectopic artery will pass very close to the usual connection of the absent ostium, whereas during a retro-infundibular course, the ectopic artery remains at a distance from the usual connection of the absent ostium (Figure 8).

This connection anomaly may be associated with a risk of sudden death on exertion, especially in high-level athletes [4]. This risk is dependent, according to retrospective studies, on the type of initial ectopic trajectory and concerns only the pre-aortic trajectory [5], and therefore the pre-infundibular, retro-infundibular or retro-aortic trajectories are not considered to be at risk. This agrees with the case of our patient who is pauci symptomatic without a personal history of resuscitated sudden death.

Sudden death is probably related to ventricular fibrillation linked to the existence of areas of fibrosis that may correspond to a chronic repetitive ischemia phenomenon observed in post-mortem studies carried out in young athletes who died of sudden death [6]. This chronic ischemia remains silent for a long time and is rarely detected by the usual techniques.

The mechanism of this chronic ischemia remains uncertain. Extrinsic compression of the ectopic artery by the pulmonary artery during extreme exertion, long presented as a probable mechanism, has never been clearly demonstrated, especially since cross-sectional imaging explicitly shows that the pre-aortic course said to be at risk is often closer to the pulmonary infundibulum than to the trunk of the pulmonary artery (7).

The question to ask is whether the ectopic coronary artery with a pre-aortic course without intramural path (by definition in this anomaly) is really a form at risk of sudden death? The problem that arises is that the various studies do not always make a difference between a pre-aortic course without an intramural pathway (which corresponds to the ectopic connections to the contralateral artery) and a pre-aortic course with an intramural pathway (which corresponds to certain ectopic connections in the contralateral sinus) where there is a sudden and significant reduction in arterial flow under extreme hemodynamic and mechanical conditions (exertion, etc.) due to anatomical abnormalities such as ellipsoidal deformation of the ostium and initial intramural segment.

The only guidelines available are North American and advise surgical correction (grade IB) of all left ANOCORs with a pre-aortic course (with or without intramural pathway), regardless of the existence of documented myocardial ischemia, and right ANOCORs with pre-aortic course (with or without intramural pathway) and associated with documented myocardial ischemia [8].

In the case of a left ANOCOR with a pre-aortic course without an intramural pathway, coronary reimplantation at the level of the usual sinus can be problematic due to the position close to the pulmonary trunk, and an unroofing-type technique (excision of the strip intramural aortic) is not possible due to the absence of an intramural pathway. The most commonly used therapeutic solution is then revascularization by arterial bypasses of the myocardial territory dependent on the ectopic artery which can expose to the risk of early involution of the arterial ducts due to the absence of significant reduction in arterial flow at the basal state in the ectopic artery. This explains the existence of practices that do not comply with the recommendations, in particular for a population of young adults where ANOCOR can be discovered by chance [9], and this all the more so as the consideration of ectopic coronary artery with pre-aortic course obviously without intramural pathway as a form at risk of sudden death remains doubtful.

In all other anatomical forms of ectopic coronary artery, without pre-aortic trajectory, therapeutic abstention is the rule, as in the case of our patient.