Dear Chris,
Sorry to hear about your chest discomfort.
You are 29 years old with no cardiac risk factors and are experiencing atypical chest discomfort. Based on your age and lack of risk factors you are in a low risk category. Moreover, your normal electrocardiogram, nuclear test and echocardiogram are more reassuring. It is very unlikely that you have blockages in the heart arteries. I have not read anything in your history that indicates you need a heart catheterization. A left heart catheterization does have some risks and I would therefore urge you to discuss this further with your cardiologist.
Thanks for your question,
CCF-MD-KE