Hi, i am 20 years old. I had cardiac arrest last june, the cause is unknown. I curently have arithmia. I was on amiodarone for one year but ive stoped it 2 months ago. I feel twitching sometimes but i was told not to worry about it. I wanted to give a brief history of my medical condition which may be helpful in answering my question today. I feel painon my chest right on my heart area sometimes when i breathe. It can last 5 to 30 seconds, depending on what i am doing. When im lying down its short but if im exercising it longer. Do you think it is related to the heart or just the muscles. If the muscle, than why is it only the left side of the chest?