Congenital anomalies of coronary arteries: role in the pathogenesis of sudden cardiac death.

After hypertrophic cardiomyopathy, coronary artery anomalies of origin from the wrong sinus of Valsalva are the second most common cause of sudden death on the athletic field in the USA. Although the right coronary artery arising from the left coronary sinus (ARCA) is four times as common as the left coronary artery arising from the anterior sinus (ALCA), it is the latter that is by far the more common cause of sudden death with or shortly after vigorous physical activity. Of the four types of ALCA, the interarterial type, where the left coronary artery passes anteriorly between the aorta and the right ventricular outflow tract, is the only type that places the patient at risk of sudden death. Another feature of this syndrome is the fact that sudden death occurs associated with or shortly after vigorous exercise and is very unusual after the patient is > 35 years of age. The mechanism by which there is sudden occlusion of the interarterial coronary artery is at present unknown, although there are a number of hypotheses involving the oblique passage of the vessel as it leaves the aorta. Sudden death is probably rare considering the number of people who have these anomalies. Symptoms premonitory to a fatal event such as exertional syncope, chest pain, or palpitations are probably common in patients at risk, and surgical correction is indicated in symptomatic patients at any age. In older asymptomatic patients, surgery is not recommended, since the incidence of sudden death in this age group is extremely small. In asymptomatic young patients, a stress test, preferably with radioisotope myocardial perfusion imaging or stress echocardiogram, should be done and surgical correction performed in those with ischemia provoked in the appropriate myocardial region. Since there is evidence that in patients who have survived a potentially fatal event, it is rare to be able to provoke ischemia with equal or greater exercise than had precipitated the malignant arrhythmia, the decision to surgically correct an asymptomatic young patient, serendipitously found to have ALCA, who has a negative exercise test, is debatable. Any decision for surgery in such patients should be made only after a full discussion of the risks pro and con surgery with the patient and the patient's family.