My father had pain below the heart which was on the rib side. What is the cause?

Hi doctor,

My father had mild chest pain. The doctor did an angiogram, and they told there is a block in the blood pumping vessel and it is closed. We planned for placing a stent. The next day, the doctor tested again and told the blood vessel is opened and it is normal. So, the stent was not placed. After a few days, my father had pain below the heart which was on the rib side, and he told something is holding in the heart. So, again we went to the cardiologist. The doctor examined him and said he is fine and there is nothing to worry. Whenever he got this pain, we consulted the cardiologist, and he said there is no problem in the heart. He got this pain for about three times till now. Again, we tested for a gastric problem and a neurological problem. That was also fine after the examination. But, still he is experiencing the same pain, and he is willing to do angiogram now. I cannot understand the problem. Please suggest.