Sudden cardiac discomfort may be caused by arrhythmia, myocardial infarction, aortic coarctation and other diseases, or it may be caused by physiological factors such as over-exercise and emotional excitement. 1. Arrhythmia: the heart beats too fast or too slow, or irregularly, caused by abnormal conduction in the heart system, and sudden cardiac discomfort and panic may occur during the attack. 2. Myocardial infarction: myocardial ischemia and hypoxia caused by obstruction of coronary arteries, resulting in the heart’s ejection of blood can not meet the normal needs of the sudden onset of cardiac discomfort, and there may be anterior precordial pressure pain. 3. Aortic coarctation: it is a serious cardiovascular emergency with a very high mortality rate. In most cases, it manifests itself as an acute onset of cardiac discomfort, which can be characterized by a feeling of suffocation and tear-like pain. 4. Physiological factors: in excessive exercise, emotional excitement, etc., the heart needs more blood, more than the myocardial pumping capacity, there will be cardiac discomfort. You can first take a full rest, if the symptoms do not ease for a long time, it is recommended to go to the hospital for a comprehensive examination, to clarify the cause of the disease and treatment according to the doctor’s instructions.