As I was waiting to have an atherectomy (rotorooter) on my LAD........the only pain I was having was in my back, a spot just to the right of my left shoulder blade.........a nitro relieved it........since that time I occasionally have a little pain in that spot.......nitro always relieves it........
I know you know your heart is in the middle of your chest leaning toward your left side, but not directly in front of the upper left side of the back. See your doctor.