Sudden cardiac death and myocardial infarction are both types of coronary heart disease, but they are different from each other. Firstly, having a myocardial infarction does not necessarily result in sudden death. Myocardial damage involves a large area of necrosis in the heart, and the patient may experience symptoms such as chest tightness, shortness of breath, chest pain, and sweating. The main symptom of sudden cardiac death is the abrupt cessation of vital signs, with breathing and pulse disappearing. This condition can be caused by a large and extensive acute myocardial infarction, but it can also be caused by other reasons such as electrolyte disturbances or malignant arrhythmias, which are different causes.