Some of the old people who have heart attack do not have any reaction, and the possible reasons for this are that the typical symptoms are not obvious, the pain threshold is higher, and the collateral circulation is better established. 1. Typical symptom is not obvious: most of the old people with heart attack have the typical symptom of persistent pressure-like pain in the anterior chest wall, accompanied by chest tightness, shortness of breath, etc. However, some of them may have the situation of not obvious symptom, and have the symptom of radiating pain, such as abdominal pain, toothache and sore throat. 2. Higher pain valves: some of the elderly have congenital high pain valves or diabetes mellitus combined with peripheral neuropathy, which will cause their ability to perceive pain to become weaker, and thus no self-consciousness of the presence of discomfort. 3. Better establishment of collateral circulation: some elderly people have collateral circulation before the onset of heart attack, which can help the body to reduce the symptoms of heart attack, but it does not mean that the situation is not dangerous, and need to go to the hospital as soon as possible for medical treatment and therapy. Heart attack is a more serious form of heart disease, if there are symptoms of discomfort, you should seek medical attention as soon as possible.