Anomalous origin of left coronary artery in young athletes with syncope

Case reports

Case 1

This 15 year old boy was a talented, competitive soccer player with a history of recurrent syncope during soccer training at the age of 6, 7, and 11. Previous investigations—including 12 lead electrocardiography, treadmill exercise testing, echocardiography, and electroencephalography—were normal. During a soccer game when he was 15, he had syncope and had to be resuscitated owing to ventricular fibrillation. On admission to our hospital he was in stable sinus rhythm, and arrhythmia did not recur.

We diagnosed anomalous origin of the left coronary artery from the right aortic sinus from transthoracic echocardiography (fig 1 and fig 2). Colour Doppler transthoracic echocardiography showed the anomalous origin as well as the interarterial course of the left coronary artery (fig 2). The diagnosis was confirmed with selective angiography. The patient recovered from mild hypoxic cerebral damage, and after 13 months of neurological rehabilitation he had elective surgery: the aortic orifice of the left coronary was excised and reimplanted into the left coronary sinus.

Fig 2

Echocardiography results for case 1. Top: Transthoracic echocardiography (parasternal short axis) showing the left coronary artery (double arrow) originating from the right aortic sinus (1) rather than from the left (2), with normal origin of the right coronary artery from the right aortic sinus (single arrow). Centre: Colour Doppler sonography showing the interarterial course of the left coronary artery (arrow) between aortic root and pulmonary artery (PA). Bottom: A slight inferior tilt of the transducer showing division of the left coronary artery (arrow) into left anterior and left circumflex branch

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Discussion

Unequivocal evidence exists that anomalous origin of a coronary artery from the opposite aortic sinus with an interarterial course is associated with a significantly increased risk of sudden myocardial ischaemia during exercise resulting in life threatening ventricular arrhythmias.1 2 The increased risk applies specifically but not exclusively to young athletes.1 2 There are two major variants of this anomaly: (a) the left main coronary artery may arise from the right aortic sinus or (b) the right coronary artery may arise from the left aortic sinus. Postmortem studies show that the risk of sudden death seems to be higher in patients with the first variant than in patients with the second; the incidence of either variant in children and adolescents from birth to the age of 21 has been estimated at 0.08%.6

Possible pathophysiological mechanisms of transient myocardial ischaemia during exercise include impaired coronary perfusion resulting from kinking at the origin of the vessel. A study by Basso and colleagues showed that enlargement of the aortic and pulmonary root due to increased cardiac output during exercise might have resulted in compression of the interarterial coronary artery segment.1 About half of the study patients with exercise induced sudden death were asymptomatic before the fatal event; the rest had a history of various cardiac complaints, such as chest pain, dyspnoea, nausea, various arrhythmias, syncope, cardiomegaly, pulmonary oedema, and myocardial infarction.1 2

Studies have shown—and our cases have confirmed—that normal 12 lead electrocardiography and even a negative exercise test by no means exclude anomalous origin of the left coronary artery and its life threatening complications.1 The anomaly can be diagnosed with transthoracic echocardiography as young athletes, being of slim build, are usually excellent subjects for this examination.6 7 Colour Doppler flow mapping is particularly useful as it helps in identifying the interarterial course of the anomalous coronary artery and provides additional information of direction of flow in the coronary vessel.7 Nevertheless, the anomaly can be missed if (as in case 1) the examiner is not aware of the typical appearance of this anomaly (fig 2) and does not focus on visualisation of the aortic origin of the coronary arteries. If the coronary artery anatomy cannot be clarified with echocardiography, magnetic resonance imaging and computed tomography are helpful, especially in adults.8 9 However, the choice of imaging method may be influenced by local expertise. Although selective coronary angiography is still considered to be the ideal investigation in patients with suspected anomaly, potentially life threatening coronary artery anomalies can sometimes be difficult to distinguish from benign variations of such anomalies.

Elective surgical repair can be accomplished with low risk, so diagnosis of anomalous origin of the left coronary artery before a life threatening or fatal event is important. After diagnosis, surgical repair is recommended for all patients with syncope or a history of transient myocardial ischaemia. Surgical techniques include excision of the orifice and reimplantation of the anomalous coronary artery into the correct sinus, as well as “unroofing procedures,” which create a link between the intramural segment of the anomalous coronary artery and the correct aortic sinus.4 5

Diagnosis of this coronary artery anomaly requires a high level of awareness, especially among all involved in the medical care of young athletes. In general, syncope in adolescents is a benign event, with a peak incidence in 15-19 year olds. However, syncope during or immediately after exercise is uncommon (incidence of 3% among children and adolescents)3 and requires thorough evaluation so that patients with potentially fatal conditions can be identified.10 We strongly recommend that evaluation with transthoracic echocardiography should be included in the investigations of all adolescents and young adults with a history of pain on exertion or syncope associated with exercise.