Occasionally we will see a dilated coronary artery of unclear cause on an echocardiogram. You do not say how dilated it is: ie: a normal coronary artery would be 2-3 mm, but a 6-7 mm coronary artery is a very different concern than a 4-5 mm coronary artery. If the imaging by CT shows no aneurysms that is good. I am not sure what is "abnormal" about the ECG? usually in the incidental finding of a dilated coronary artery, the ECG is normal. Additionally if your son is a high level athlete then he should have an exercise stress test performed (with nuclear imaging if possible to look for areas of myocardial perfusion abnormalitities) before giving him full clearance to participate in sports. All things being equal this may be a variant of normal, but we would agree it needs to be followed.
Thank you very much for your response. The ECG was abnormal in the way that caused a concern for left ventricular hypertrophy (no more detail given to a lay person), but LVH was ruled out with echo. The ECG was repeated later and was normal--sorry I neglected that part in my original post. The CT scan did not reveal any aneurysms. Although the exact measurement of the vessel diameter was not given to me, I didn't come away with the impression it was 3x normal size. No exercise stress test has been recommended.
It sounds as though the real possibility of a normal variant rules out the idea of a one size fits all ban on competitive sports(?) Could a larger diameter coronary artery actually be an asset, by allowing more blood flow to the cardiac muscle?
The "LVH on ECG" is a common cause of referral to cardiologists and it is usually negative. As far as the coronary artery is concerned, again, it really depends upon how large it is...if your child is a super athlete it could be larger just because there is an athletic heart. I think you should discuss this in more detail with your child's cardiologist, who has the information, and ask if there is any indication for a stress test in his particular condition.