Cardiologist doctor near to me So take care of your heart , before a heart attack Inside a Heart Attack Plaque is hard on the outside and mushy on the inside and Sometimes that hard outer shell cracks. When this happens, a blood clot forms. If it completely blocks your artery, it cuts off the blood supply to part of your heart. Blood carries oxygen, and a shortage of that can quickly damage the organ and possibly kill you. The attack is sudden, and it's important to get medical help right away.