William E. Lawson, MD, is professor of medicine, State University Health Sciences Center, Stony Brook, New York.

The case report by Gandhi and Rosenberg illustrates some of the concerns regarding coronary anomalies. The essential questions for cardiologists regarding coronary artery anomalies are who and how to screen, and what to do with the results.^1,2 Coronary artery anomalies are uncommon, often difficult to diagnose, and carry an uncertain prognosis in the majority of cases. To be defined as a coronary anomaly, most would specify that the feature occurs in < 1% of the population. The symptoms associated with anomalies range from none (most commonly) to severe and may include: dyspnea, chest pain, exertional angina, myocardial infarction, ventricular fibrillation, syncope, sudden death, and cardiomyopathy. The lesions most clearly associated with ischemia and sudden death following exercise have included anomalous coronary artery from the opposite sinus, with a reported mortality risk of up to 57% for left and 25% for right anomalous origins, and origin of the left coronary artery from the pulmonary artery. Large fistulas have been associated with coronary steal and volume overload from left to right shunting, as well as endocarditis risk. Many of the other described anomalies (anomalies of origin, course, or artery size, muscle bridges) are represented with an increased frequency at autopsy for cardiac death, but no causal relation can be clearly established.

The population meriting screening should probably include individuals engaging in competitive or high-level sports activity, those with a family history of sudden death or congenital heart disease, and patients with cardiac signs or symptoms.³ The routine nondiagnostic tests available, including chest x-ray, electrocardiogram (ECG), transthoracic echocardiography, treadmill and radionuclide stress testing, and Holter monitoring, are all reported to lack sensitivity and specificity. Although coronary angiography has been the historical gold standard for detecting the presence of coronary artery anomalies, it has been surpassed in many instances by the less invasive anatomic tests of magnetic resonance imaging and computed tomography angiogram, followed by transesophageal echocardiography.⁴ In most cases, detecting the coronary anomaly is not enough to understand the potential physiologic effect and prognostic importance. Stress echocardiogram with dobutamine (Dobutrex) and volume loading is one common strategy to determine the clinical importance and prognostic relevance of anomalies. In the catheterization laboratory, ECG and hemodynamic assessment during exercise, intravascular ultrasound, and intra-coronary pressure wire measurement of fractional flow reserve at rest and after adenosine maximal vasodilation have all been used to determine the physiologic significance of coronary anomalies.

References

1. Angelini P. Coronary artery anomalies- current clinical issues: definitions, classification, incidence, clinical relevance, and treatment guidelines. Tex Heart Inst J. 2002;29(4):271-278.
2. Angelini P, Velasco JA, Flamm S. Coronary anomalies: incidence, pathophysiology, and clinical relevance. Circulation. 2002; 105(20):2449-2454.
3. Eckart RE, Jones SO IV, Shry EA, et al. Sudden death associated with anomalous coronary origin and obstructive coronary disease in the young. Cardiol Rev. 2006; 14(4):161-163.
4. Kim SY, Seo JB, Do KH, et al. Coronary artery anomalies: classification and ECG-gated multi-detector row CT findings with angiographic correlation. Radiographics. 2006;26(2):317-333.