Acute rheumatic fever is the most important cause of mitral stenosis, accounting for about 80% to 90% of the total number of patients. In people with rheumatic heart disease, the incidence of mitral stenosis is 65% to 100%, and the incidence of simple mitral stenosis is 25% to 40%; mitral stenosis is mostly seen in women, with a male to female ratio of (2:3)-(3:4). Other causes are less common, and with the aging of our population, the proportion of stenosis due to degenerative valves in the elderly is increasing. Patients with severe mitral stenosis undergo early start surgery even if they are asymptomatic. Patients may be asymptomatic for years after medical treatment, but the damage caused by mitral valve lesions never stops getting worse. The risk of early surgery in patients with mitral stenosis is minimal, generally less than 1%, and the long-term prognosis is excellent.