Top left shoulder pain with exertion. no other symptoms. rest makes it go away. normal nuclear stress test 6 years ago. could this be angina or an injury? no shortness of breath. no chest pain. just pain on top of shoulder?

This is more likely to be a musculoskeletal issue with your shoulder but to be certain, you should have this re-evaluated by your cardiologist who did your stress test 6 years ago. Heart disease could have developed in 6 years so the only way to know for certain would be to get tested again and see if there are any cardiac changes while you are having the shoulder pain. Good luck!

When you state exertion are you referring to shoulder discomfort with use of the shoulder or with brisk walking,climbing stairs,etc? If the latter, a cardiac cause is a possibility vs a shoulder cause such as tendinitis, rotator cuff pathology,etc. With the latter, a stress test is indicated.