Having spasms on left pectoral muscle spanning from armpit to sternum. no pain, but i want opinions that its more muscular than cardiovascular - any insight on differentiating would be helpful. i have not had a recent injury to the area?

If you feel the muscle twitch or spasm, underlying heart disease is less likely. Chest pain due to heart problem is usually associated with other symptoms such as sweating (diaphoresis) and shortness of breath, usually triggered with exertion or stress (increased heart rate or blood pressure), relieved with rest. Occasional muscle twitching or spasm is often not associated with other symptoms.