Left back pain underneath the shoulder blade may be related to local trauma, local soft tissue inflammation, heart disease and so on. 1. Local trauma: local soft tissue injury, scapula fracture, etc. due to the left back below the scapula being hit by external force, may lead to left back below the scapula pain. 2. Local soft tissue inflammation: common as myofasciitis, mainly due to repetitive or prolonged activities leading to muscle fiber overload, muscle hypoxia and local ischemia, may lead to left back pain under the scapula. 3. Heart disease: common such as myocardial infarction, angina pectoris, etc., mainly due to myocardial ischemia, resulting in pain in the precordial area, which may lead to pain in the left dorsal subscapularis after visceral reflexes. Therefore, the left back pain below the shoulder blade has more causes, it is recommended to seek medical advice as soon as possible to identify the causes, and then follow the doctor’s instructions to be targeted treatment.