Background: We describe a patient with Duchenne Muscular Dystrophy (DMD) and incidental finding of anomalous aortic origin of the left coronary artery (AAOLCA) from the right coronary sinus with an inter-arterial course. There are no documented associations between human dystrophinopathies and anomalous coronary artery origins. Surgical repair is recommended for this cardiac lesion in typically developing patients due to the risk of sudden cardiac death (SCD), which occurs predominantly during competitive sports. In a patient with DMD, there is known myocyte conversion to fibrofatty tissue, but also decreased myocardial demand, making management of the coronary anomaly not as straightforward.

Case Description: A currently nine-year-old male with DMD was diagnosed with the AAOLCA in the neonatal period. CT angiography confirmed the inter-arterial course of the anomalous coronary artery. He is still ambulatory and not reliant on positive pressure ventilation. He has had no significant systolic or diastolic cardiac dysfunction. The patient has had no concerning cardiac symptoms, including no chest pain, dyspnea, palpitations, easy fatigability, pre-syncope or syncope with or without exertion. He is very active and reportedly keeps up with his peers. His electrocardiogram shows sinus rhythm with a minor right ventricular conduction delay and no significant ST segment abnormalities.

Discussion: The mechanism of SCD in AAOCA is not clearly defined but is likely ischemic in nature. SCD frequently occurs during or shortly after exercise. It is thought that there is insufficient coronary blood flow to meet myocardial oxygen demand, which leads to ischemia and subsequent fatal ventricular tachyarrhythmias. High risk features include narrow coronary ostium, “slit-like” coronary ostium, acute coronary artery angulation, inter-arterial segment, and intramural course (which are thought to be compressed during systolic expansion of the great vessels during exercise). Recommended management for patients with AAOLCA is surgical correction, which has favorable peri-operative outcomes and low operative mortality. Reported risk of post-operative inducible ischemia, however, is 37% and of SCD is 1.5%.
DMD patients undergo progressive muscle degeneration and weakness in a proximal-to-distal manner. Physical activity decreases steadily with loss of ambulation. While there is not any increased risk of congenital heart disease in patients with dystrophinopathies, functional cardiac involvement is well-described and is characterized by myocardial replacement by connective tissue, fibrosis, and/or fat leading to dilated cardiomyopathy, arrhythmias, and eventual demise. DMD patients are at increased risk of cardiopulmonary compromise during anesthesia due in part to cardiomyopathy, weak airway muscles and risk for rhabdomyolysis, hyperkalemia, and hyperthermia.

Conclusion: In a patient with DMD who is not expected to participate in competitive athletics but who is still ambulatory and active, management of his otherwise potentially high risk inter-arterial AAOLCA is not straightforward. The 6.3% mortality rate from AAOCA would not apply, given his lower expected level of physical exertion and decreased myocardial demand. Additionally, he is at higher peri-operative risk than a non-DMD patient. It is unclear if the eventual cardiovascular changes associated with his dystrophinopathy will increase his risk for ischemic incidences related to his AAOLCA (or, for that matter, from its repair). There is evidence that coronary dilation potential is diminished in patients with dilated cardiomyopathy, which may be protective in the setting of a proximal stenosis. Unfortunately, the longer we wait to decide if he would benefit from surgical repair (using risk stratification techniques), the higher his surgical risk becomes due to cardiopulmonary decline.