Anomalous Aortic Origin of a Coronary Artery

Anomalous aortic origin of a coronary artery (AAOCA) describes a coronary artery arising from the opposite sinus of Valsalva. The right coronary artery arises from the left sinus (AAORCA, about 0.1 to 0.3% of the population) or the left coronary artery arises from the right sinus (AAOLCA, about 0.02 to 0.1%).

Courses are interarterial (between the aorta and pulmonary artery), intramural (within the aortic wall), prepulmonic, retroaortic or subpulmonic (septal). High risk anatomy is an interarterial course with an intramural segment, a slit like or narrowed ostium, an acute take off angle and proximal hypoplasia.

AAOLCA carries more risk than AAORCA. AAOCA accounts for roughly 10 to 20% of sudden cardiac deaths in young athletes in registry series, with most events under 35 years and during or soon after exertion.

Pathophysiology. Exertion increases cardiac output and widens the aortic root and pulmonary trunk, which compress the interarterial segment. The intramural segment narrows as the aortic wall expands, and the slit like ostium closes during systole and diastole. Dynamic obstruction causes ischaemia and ventricular arrhythmia.

Ischaemia may be intermittent and absent at rest, so a normal resting test does not exclude risk. After 35 years the anomalous vessel also develops atherosclerosis.

• Most patients are asymptomatic and the diagnosis is made by imaging for another reason.
• Exertional chest pain, syncope or presyncope, palpitations, exertional dyspnoea, and cardiac arrest. About a third to a half of those who die have prior symptoms.
• Examination and resting ECG are usually normal.

Red flags.

• Exertional syncope or chest pain
• Resuscitated cardiac arrest
• Ventricular arrhythmia on exercise
• Inducible ischaemia in the territory of the anomalous vessel
• Interarterial course with an intramural segment, a slit like ostium or an acute take off angle (especially AAOLCA)

• Coronary CT angiography: the key test. It defines origin, course, intramural length, ostial area and shape (slit like, oval), take off angle and relation to the pulmonary trunk. Cardiac MRI is an alternative without radiation.
• Echocardiography: identifies the ostia in children and excludes other structural disease.
• Exercise ECG: poor sensitivity; a normal result does not exclude risk.
• Stress imaging (perfusion MRI, nuclear perfusion or stress echocardiography, with dobutamine when exercise cannot be performed): detects inducible ischaemia in the territory of the anomalous vessel.
• Invasive coronary angiography with intravascular ultrasound: assesses the intramural segment and ostial dimensions. Fractional flow reserve during dobutamine challenge assesses functional significance.
• Ambulatory ECG: ventricular arrhythmia.

Differential diagnosis.

• ALCAPA and ARCAPA
• Atherosclerotic coronary disease
• Coronary vasospasm
• Myocardial bridging
• Hypertrophic cardiomyopathy
• Arrhythmogenic cardiomyopathy
• Inherited channelopathy (long QT syndrome, catecholaminergic polymorphic ventricular tachycardia)
• Spontaneous coronary artery dissection
• Myocarditis
• Neurally mediated syncope

• Surgery is advised for AAOCA of either vessel with symptoms attributable to it, inducible ischaemia, or survived cardiac arrest, and is reasonable in asymptomatic AAOLCA with an interarterial course. It is considered in asymptomatic AAORCA with high risk features. Surgery is not needed for benign courses (prepulmonic, retroaortic, septal) with no ischaemia.
• Operations: unroofing of the intramural segment with creation of a neo ostium (preferred when an intramural segment is present), reimplantation, pulmonary artery translocation for an interarterial course without an intramural segment, or bypass grafting with ligation of the proximal anomalous vessel when other repair is not feasible or atherosclerosis is present. Operative mortality is low (under 2%). Late problems are ostial restenosis, aortic regurgitation from commissural distortion, and residual ischaemia.
• Medical therapy before or without surgery: bisoprolol 5 mg orally once daily, increased to 10 mg once daily as needed, maximum 20 mg daily; do not exceed 10 mg daily at creatinine clearance under 20 mL/min or in severe liver impairment; monitor heart rate and blood pressure. Evidence of benefit is limited. After bypass grafting: aspirin 75 to 100 mg orally once daily indefinitely (usual maximum 325 mg daily).
• Exercise: avoid competitive sport and strenuous exertion with AAOLCA and an interarterial course until repaired. With AAORCA, participation is decided case by case after evaluation. After repair, return to sport at about 3 months if asymptomatic with no inducible ischaemia or arrhythmia on maximal exercise testing.
• Percutaneous stenting of the intramural segment is investigational.

Special groups. Symptomatic women who plan pregnancy are repaired first.

Monitoring. Non-operated: annual symptom review, repeat imaging at transition to adult care, and stress imaging when symptoms change. After repair: CT angiography and stress testing at 3 to 6 months, then every 1 to 3 years for ostial narrowing and ischaemia.

Referral and escalation. Refer to a congenital heart disease centre with coronary surgery and sports cardiology experience. Urgent for syncope, ischaemia or arrhythmia.