Left bundle branch block (LBBB) is a condition where the electrical signals in the heart are delayed or blocked in the left bundle branch, which is part of the heart's conduction system. This can lead to a slower and less coordinated contraction of the left ventricle, affecting the heart's ability to pump blood efficiently. LBBB is often identified through an electrocardiogram (ECG), which shows characteristic changes in the heart's electrical activity. It can be associated with various heart conditions, including coronary artery disease and hypertension, and may increase the risk of heart failure or other complications.