Hidden pain on the left side of the fossa of the heart may be caused by myocardial infarction, chronic pancreatitis and pleurisy. 1. Myocardial infarction: Myocardial infarction occurs on the basis of coronary atherosclerotic heart disease. Patients will experience squeezing pain on the left side of the heart fossa, usually accompanied by symptoms such as chest tightness, panic and shortness of breath. 2. Chronic pancreatitis: Chronic pancreatitis is a chronic inflammatory disease with irreversible changes in pancreatic tissue and function caused by a variety of etiologies. The patient will have the symptom of vague pain in the fossa of the heart, and some patients will also have nausea, vomiting, jaundice, abdominal distension and other symptoms. 3. Pleurisy: Pleurisy refers to the inflammation of the pleura caused by pathogenic factors that stimulate the pleura. The patient will have a vague pain on the left side of the heart, usually accompanied by cough, dyspnea, fever and other symptoms. When the patient appeared in the left side of the fossa of the heart, need to go to the hospital in a timely manner, clear cause of the disease and actively cooperate with the doctor’s treatment.