The signs of sudden heart attack are mainly in the following clinical aspects: first, the degree of chest pain is aggravated, for example, in the past, patients with chest pain generally lasted for several minutes and could be relieved by resting or applying nitroglycerin, but now it lasts longer and even reaches more than half an hour, and the effect of applying drugs such as nitroglycerin is not good. Secondly, the frequency of attacks increases, for example, in the past, a certain amount of activity was required before an attack could occur, but now the attack can occur with a little activity or even at rest, which leads to a significant increase in the frequency of attacks, suggesting that the lesion of the heart is aggravating and a heart attack may occur. Third, the pain radiates to new parts, for example, the pain was only in the heart area before, but now it may cause pain in the left back or even the upper limbs in addition to the heart area, and finally the severity of the pain increases, especially when accompanied by sweating, nausea and vomiting and other symptoms, we should pay attention to the possibility of sudden heart attack.