Left arm numbness of and on since march to present.have had 5 ekg, er visit with cbc, cmp, tropononin1 test.vascular screen, all normal.what could b cause?

Non-cardiac?: This may represent a nerve compression or impingement issue. If you have cardiac risk factors, a stress test may be a good idea, as troponin and ekg may be normal even with signifiant coronary blockage.

Maybe Orthopedic: Consider your cervical spine, which is where the nerves for your arm leave the spinal cord. You could have a pinched nerve. Also consider animpingement in the shoulder. A cervical MRI would reveal any impingement in the neck; make sure you get a weight-bearing MRI (done seated rather than laying down). An EMG would help determine if impingement is in occurring in the neck or shoulder.