Coronary heart disease myocardial infarction will have precursors, such as a few days or a week before the appearance of the infarction, will feel particularly weak or chest tightness, discomfort, feel panic and shortness of breath when slightly active, a little thing may feel particularly irritable, sinking or angina and other precursors, angina may have been there before, will appear more intense and frequent pain than before or just appear angina Symptoms, pain longer than before, and there is no obvious cause, not like anger, anxiety or lack of sleep, these triggers will appear, if you take nitroglycerin, and the effectiveness of the treatment is not good. The angina attack is also accompanied by nausea, vomiting, bradycardia, acute cardiac insufficiency, severe arrhythmias, and large fluctuations in blood pressure, which are all precursors to myocardial infarction.