The severity of a moderate left deviation of the cardiac axis is related to the etiology of the symptoms. Generally, physiological factors cause left deviation which is not serious; pathological factors cause more serious. 1. Physiological factors: such as pregnancy, obesity and other factors lead to left deviation of the cardiac axis, which is not a serious disease. Patients do not need special treatment and can be relieved by adjusting their dietary structure and giving birth. 2. Pathological factors: such as ventricular hypertrophy, left anterior branch block, left ventricular volume overload and other diseases, patients will have left deviation of the cardiac electrical axis, which is a serious disease. It is generally recommended that patients clarify the cause of the disease as soon as possible to avoid sudden death due to heart failure. It is recommended that patients with left deviation of EKG should go to the hospital in time and choose the appropriate treatment plan under the doctor’s guidance, avoiding self-medication and delaying the condition.