Left atrial hypertrophy manifests as an increase in the inner diameter of the atria and thickening of the myocardial fibers and is caused by an increase in the load on the left atrium due to various causes. The main cause of left atrial hypertrophy is overload of the left atrium due to various organic heart diseases. Heart diseases that cause enlarged left atrium include hypertension, coronary artery disease, arrhythmia, heart failure, cardiomyopathy, congenital heart disease, rheumatic heart disease, and heart valve disease. The above diseases lead to an increased load on the left atrium. On the one hand, the increased volume of blood in the atrium when the atrium is filled, or the increased pressure, leads to an enlargement of the inner diameter of the atrium to accommodate more blood, and on the other hand, the increased resistance to ejection of blood from the left atrium causes the myocardium to continuously increase its contraction force to ensure ejection of blood. To use an analogy, the left atrium is like a balloon blown by a child, with a certain elasticity, the more you blow or fill it with water, the bigger the balloon becomes. The increased load on the left atrium leads to enhanced myocardial metabolism, thickening of myocardial fibers, and thus compensatory hypertrophy of the atrium to maintain blood circulation. In the later stage, the myocardium loses compensation, myocardial remodeling and myocardial partial fibrosis, and contractility is weakened. At this time, the left atrial blood cannot be fully drained into the left ventricle during diastole, causing severe left atrial stasis and further enlargement of the left atrium. At the same time, there are a series of neurological, humoral and endocrine factors in the enlargement of the atria. Echocardiography makes it easy to check for left atrial hypertrophy. Left atrial hypertrophy is a change in the structure of the heart caused by the progression of heart disease, and it can also lead to the development of various atrial arrhythmias.