Left anterior branch block is an abnormal heart point condition that falls within the range of intraventricular conduction block, indicating abnormal conduction. The internal conduction system is mainly composed of three parts: right bundle branch, left anterior branch, and left posterior branch. Most cases are prone to heart disease and rheumatism, and normal people also have right bundle branch block and left bundle branch block, which occur in patients with heart failure and myocardial infarction. Left anterior branch block is more common in left anterior branch block, and left posterior branch is less common. Left anterior branch block is a slender branch that is prone to ischemic injury, commonly seen in coronary artery disease, and also in hypertension, cardiomyopathy, and myocarditis. It is also common in people with abnormal blood pressure control. Left anterior branch block without organic heart disease has a good prognosis. Left anterior branch block is often associated with right bundle branch block, and left anterior branch block is more common in clinical practice.