stents not working

My finacee wants to know why he has sharp pains in his chest he looses shortness of breath and his head gets dizzy. He feels like he has to go to the restroom. He has has 4 heartattacks and he has stents place in him. They said that it is not working. They actually say that it's nothing that tey can do. I live in houston as I see it;s a great place to be treated but very expensive I really need some advice.