Although incomplete intra-atrial block is not hemodynamically significant, half of patients often have a history of recurrent paroxysmal atrial fibrillation or atrial flutter, and 40% of patients may have a history of atrial prophase contractions and atrial tachycardia. Patients may have symptoms such as chest tightness, shortness of breath, and irregular heartbeat. Incomplete intra-atrial conduction block is caused by ectopic excitation of the impulse in the atria, which invades the sinus node during depolarization and prevents or delays the downward transmission of the excitation. Incomplete intra-atrial block is mostly seen in organic heart disease, such as rheumatic heart disease mitral stenosis, hypertension, heart failure, coronary artery disease, myocardial infarction, myocarditis, certain congenital heart diseases (such as atrial septal defect), cardiomyopathy, chronic pericarditis, hyperkalemia, increased vagal tone, digitalis and quinidine effects can lead to incomplete intra-atrial block. Most of the cases reported in China have organic heart disease, such as coronary artery disease, cardiomyopathy, hypertensive heart disease, rheumatic heart disease, chronic obstructive pulmonary disease, constrictive pericarditis, and sick sinus node syndrome. Intra-atrial conduction disturbances in the elderly may be related to degenerative changes in cardiac conduction tissue.