The most common type of arrhythmia in patients with rheumatic heart disease and mitral stenosis is atrial fibrillation. The reason for atrial fibrillation is that mitral stenosis can lead to increased pressure in the left atrium, which over time can lead to structural and electrophysiological abnormalities in the left atrium, eventually leading to abnormal pulsations in the atrium and resulting in atrial fibrillation. For patients with rheumatic heart disease and mitral stenosis with atrial fibrillation, in addition to controlling the ventricular rate, anticoagulant drugs should be given to prevent intra-atrial thrombosis. The purpose of intra-atrial thrombosis prophylaxis is to prevent cerebral embolism, lower extremity artery embolism, renal artery embolism, and other embolisms in the arterial system.