The pain on the left side of the heart socket may be caused by costochondritis, angina pectoris, myocardial infarction, trauma, pericarditis and other reasons. 1. Chondromalacia: The cause of chondromalacia may be viral infection, chronic strain of thoracic and rib joint ligaments, endocrine abnormalities and other factors. Patients may have pain and pressure in the chest area, which is manifested as pain on the left side of the heart socket. 2. Angina pectoris: coronary artery stenosis or even occlusion, resulting in myocardial ischemia, patients may experience chest pain, chest tightness, shortness of breath and other symptoms, rest or nitroglycerin can relieve the symptoms. 3. Myocardial infarction: acute occlusion of coronary artery, myocardial ischemia and necrosis, which is more serious than angina pectoris, the patient may have squeezing pain in the anterior region of the heart, chest tightness, dyspnea, and even a sense of imminent death, and the symptoms can not be relieved by resting or taking nitroglycerin. 4. Trauma: trauma caused by chest wall soft tissue injury or rib injury, will also appear in the left side of the fossa of the heart pain symptoms. 5. Pericarditis: acute inflammatory reaction and exudation occur in the pericardium due to various reasons such as infection, autoimmune and other factors, and the patient has fever, chest pain, dyspnea, heart failure and other manifestations, which can also be manifested as pain in the left side of the heart socket. There are many causes of pain on the left side of the fossa, and it is recommended that patients go to regular hospitals in time to find out the cause of the disease and actively treat it.