Discussion
We present a rare case with anomalous left main (LM) coronary artery
arising from the opposite side with a superadded severe atherosclerotic
disease involving both the normal and the anomalous arteries. Based on
its course, anomalous left main arising from the opposite side had been
classified as follows: A. Passing anterior to the aorta in the right
ventricular outflow, B. Inter-arterial course (between the aorta and the
pulmonary artery), C. Courses through the crista of the septum, D.
Passing posterior to the aortic root (2, 3). Based on this
classification, our case had combined anomalous origin of the LM
coronary artery and abnormal course including type B and D.
Coronary artery anomalies are very rare congenital cardiac disorders,
with variable incidence reported in literature and wide range of
clinical presentation (1). LM arising from the opposite sinus of
Valsalva or the proximal segment of the right coronary artery is an
extremely rare coronary anomaly with a reported incidence of 0.09 to
0.11% in the general population (4). Majority of the anomalous origin
of the coronary arteries are benign, however clinical presentation may
vary according to the left main course, and may presents present with
sudden death, arrhythmias or myocardial ischemia (3). Pathophysiology
behind this can be explained as follows (5): The slit like orifice of
the anomalous coronary artery may lead to loss of blood flow, possible
compression during its course especially in the interarterial course, or
it may be vulnerable to the process of atherosclerosis as in our case.
The incidence of atherosclerotic disease involvement in anomalous
coronary arteries is controversial and ranging from 1.7% to 72.2%
according to previously published reports (1). This variation in the
incidence could be related to the patient characteristics included or
the imaging modality utilized for diagnosis (1). Certain reports
demonstrated that anomalous coronary arteries are comparable to normal
coronaries in the potential for developing atherosclerosis (6). Few
studies have reported that anomalous left coronary arteries arising from
the opposite side as in our case are more vulnerable to develop
atherosclerosis (7). A superadded significant atherosclerotic disease in
the anomalous coronary arteries poses a high therapeutic challenge due
to the difficulties in utilizing percutaneous coronary interventions
taking in consideration the complex anatomical findings and the
increased fluoroscopic times.
Surgical intervention is recommended once diagnosis is established
especially for those patients with the interarterial course (2).
Modalities of surgical intervention included: Unroofing of the proximal
left main intramural course, Ostial re-implantation, Coronary artery
bypass grafting and pulmonary artery translocation(2). The complex
anomalous anatomy with superadded atherosclerotic severe atherosclerotic
disease involving the normal and anomalous coronary arteries in our case
scenario made us reach an agreement to choose coronary artery bypass
grafting as a valid choice.
To conclude, despite the fact that anomalous origin of the left main
coronary artery is a rare congenital anomaly, it should be kept in mind
as a possible diagnosis. Coronary computed tomography is an excellent
diagnostic modality to clarify its course.